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Sample records for derivatives stabilize plausible

  1. Stability-Derivative Determination from Flight Data

    NASA Technical Reports Server (NTRS)

    Holowicz, Chester H.; Holleman, Euclid C.

    1958-01-01

    A comprehensive discussion of the various factors affecting the determination of stability and control derivatives from flight data is presented based on the experience of the NASA High-Speed Flight Station. Factors relating to test techniques, determination of mass characteristics, instrumentation, and methods of analysis are discussed. For most longitudinal-stability-derivative analyses simple equations utilizing period and damping have been found to be as satisfactory as more comprehensive methods. The graphical time-vector method has been the basis of lateral-derivative analysis, although simple approximate methods can be useful If applied with caution. Control effectiveness has been generally obtained by relating the peak acceleration to the rapid control input, and consideration must be given to aerodynamic contributions if reasonable accuracy is to be realized.. Because of the many factors involved In the determination of stability derivatives, It is believed that the primary stability and control derivatives are probably accurate to within 10 to 25 percent, depending upon the specific derivative. Static-stability derivatives at low angle of attack show the greatest accuracy.

  2. Extraction of stability and control derivatives from orbiter flight data

    NASA Technical Reports Server (NTRS)

    Iliff, Kenneth W.; Shafer, Mary F.

    1993-01-01

    The Space Shuttle Orbiter has provided unique and important information on aircraft flight dynamics. This information has provided the opportunity to assess the flight-derived stability and control derivatives for maneuvering flight in the hypersonic regime. In the case of the Space Shuttle Orbiter, these derivatives are required to determine if certain configuration placards (limitations on the flight envelope) can be modified. These placards were determined on the basis of preflight predictions and the associated uncertainties. As flight-determined derivatives are obtained, the placards are reassessed, and some of them are removed or modified. Extraction of the stability and control derivatives was justified by operational considerations and not by research considerations. Using flight results to update the predicted database of the orbiter is one of the most completely documented processes for a flight vehicle. This process followed from the requirement for analysis of flight data for control system updates and for expansion of the operational flight envelope. These results show significant changes in many important stability and control derivatives from the preflight database. This paper presents some of the stability and control derivative results obtained from Space Shuttle flights. Some of the limitations of this information are also examined.

  3. Summary of methods for calculating dynamic lateral stability and response and for estimating aerodynamic stability derivatives

    NASA Technical Reports Server (NTRS)

    Campbell, John P; Mckinney, Marion O

    1952-01-01

    A summary of methods for making dynamic lateral stability and response calculations and for estimating the aerodynamic stability derivatives required for use in these calculations is presented. The processes of performing calculations of the time histories of lateral motions, of the period and damping of these motions, and of the lateral stability boundaries are presented as a series of simple straightforward steps. Existing methods for estimating the stability derivatives are summarized and, in some cases, simple new empirical formulas are presented. Detailed estimation methods are presented for low-subsonic-speed conditions but only a brief discussion and a list of references are given for transonic and supersonic speed conditions.

  4. Process for stabilizing the viscosity characteristics of coal derived materials and the stabilized materials obtained thereby

    DOEpatents

    Bronfenbrenner, James C.; Foster, Edward P.; Tewari, Krishna

    1985-01-01

    A process is disclosed for stabilizing the viscosity of coal derived materials such as an SRC product by adding up to 5.0% by weight of a light volatile phenolic viscosity repressor. The viscosity will remain stabilized for a period of time of up to 4 months.

  5. Estimation of Aerodynamic Stability Derivatives for Space Launch System and Impact on Stability Margins

    NASA Technical Reports Server (NTRS)

    Pei, Jing; Wall, John

    2013-01-01

    This paper describes the techniques involved in determining the aerodynamic stability derivatives for the frequency domain analysis of the Space Launch System (SLS) vehicle. Generally for launch vehicles, determination of the derivatives is fairly straightforward since the aerodynamic data is usually linear through a moderate range of angle of attack. However, if the wind tunnel data lacks proper corrections then nonlinearities and asymmetric behavior may appear in the aerodynamic database coefficients. In this case, computing the derivatives becomes a non-trivial task. Errors in computing the nominal derivatives could lead to improper interpretation regarding the natural stability of the system and tuning of the controller parameters, which would impact both stability and performance. The aerodynamic derivatives are also provided at off nominal operating conditions used for dispersed frequency domain Monte Carlo analysis. Finally, results are shown to illustrate that the effects of aerodynamic cross axis coupling can be neglected for the SLS configuration studied

  6. Summary of Methods for Calculating Dynamic Lateral Stability and Response and for Estimating Lateral Stability Derivatives

    NASA Technical Reports Server (NTRS)

    Campbell, John P; Mckinney, Marion O

    1951-01-01

    A summary of methods for making dynamic lateral stability and response calculations and for estimating the aerodynamic stability derivatives required for use in these calculations is presented. The processes of performing calculations of the time histories of lateral motions, of the period and damping of these motions, and of the lateral stability boundaries are presented as a series of simple straightforward steps. Existing methods for estimating the stability derivatives are summarized and, in some cases, simple new empirical formulas are presented. Reference is also made to reports presenting experimental data that should be useful in making estimates of the derivatives. Detailed estimating methods are presented for low-subsonic-speed conditions but only a brief discussion and a list of references are given for transonic- and supersonic-speed conditions.

  7. Comparison of several methods for estimating low speed stability derivatives

    NASA Technical Reports Server (NTRS)

    Fletcher, H. S.

    1971-01-01

    Methods presented in five different publications have been used to estimate the low-speed stability derivatives of two unpowered airplane configurations. One configuration had unswept lifting surfaces, the other configuration was the D-558-II swept-wing research airplane. The results of the computations were compared with each other, with existing wind-tunnel data, and with flight-test data for the D-558-II configuration to assess the relative merits of the methods for estimating derivatives. The results of the study indicated that, in general, for low subsonic speeds, no one text appeared consistently better for estimating all derivatives.

  8. Computational Methods for Dynamic Stability and Control Derivatives

    NASA Technical Reports Server (NTRS)

    Green, Lawrence L.; Spence, Angela M.; Murphy, Patrick C.

    2003-01-01

    Force and moment measurements from an F-16XL during forced pitch oscillation tests result in dynamic stability derivatives, which are measured in combinations. Initial computational simulations of the motions and combined derivatives are attempted via a low-order, time-dependent panel method computational fluid dynamics code. The code dynamics are shown to be highly questionable for this application and the chosen configuration. However, three methods to computationally separate such combined dynamic stability derivatives are proposed. One of the separation techniques is demonstrated on the measured forced pitch oscillation data. Extensions of the separation techniques to yawing and rolling motions are discussed. In addition, the possibility of considering the angles of attack and sideslip state vector elements as distributed quantities, rather than point quantities, is introduced.

  9. Computational Methods for Dynamic Stability and Control Derivatives

    NASA Technical Reports Server (NTRS)

    Green, Lawrence L.; Spence, Angela M.; Murphy, Patrick C.

    2004-01-01

    Force and moment measurements from an F-16XL during forced pitch oscillation tests result in dynamic stability derivatives, which are measured in combinations. Initial computational simulations of the motions and combined derivatives are attempted via a low-order, time-dependent panel method computational fluid dynamics code. The code dynamics are shown to be highly questionable for this application and the chosen configuration. However, three methods to computationally separate such combined dynamic stability derivatives are proposed. One of the separation techniques is demonstrated on the measured forced pitch oscillation data. Extensions of the separation techniques to yawing and rolling motions are discussed. In addition, the possibility of considering the angles of attack and sideslip state vector elements as distributed quantities, rather than point quantities, is introduced.

  10. Heuristic Elements of Plausible Reasoning.

    ERIC Educational Resources Information Center

    Dudczak, Craig A.

    At least some of the reasoning processes involved in argumentation rely on inferences which do not fit within the traditional categories of inductive or deductive reasoning. The reasoning processes involved in plausibility judgments have neither the formal certainty of deduction nor the imputed statistical probability of induction. When utilizing…

  11. Stability evaluation of Styrylpyrone derivative (SPD) incorporated products

    NASA Astrophysics Data System (ADS)

    Bahtiar, Adibah Ahamad; Nor, Norefrina Shafinaz Md.; Ibrahim, Nazlina

    2015-09-01

    Styrylpyrone derivative (SPD) from Goniothalamus umbrosus has been shown to have antiviral properties against Herpes Simplex virus type-1 (HSV-1). This study aimed to evaluate the purity of isolated SPD and stability of SPD-incorporated formulations. Pure SPD was isolated from dried roots of G. umbrosus as confirmed by GC-MS. Two types of SPD-incorporated products (ointment and gel) were produced. Both products showed stable physical properties after two months and retained the SPD content for one month.

  12. The transformation of aerodynamic stability derivatives by symbolic mathematical computation

    NASA Technical Reports Server (NTRS)

    Howard, J. C.

    1975-01-01

    The formulation of mathematical models of aeronautical systems for simulation or other purposes, involves the transformation of aerodynamic stability derivatives. It is shown that these derivatives transform like the components of a second order tensor having one index of covariance and one index of contravariance. Moreover, due to the equivalence of covariant and contravariant transformations in orthogonal Cartesian systems of coordinates, the transformations can be treated as doubly covariant or doubly contravariant, if this simplifies the formulation. It is shown that the tensor properties of these derivatives can be used to facilitate their transformation by symbolic mathematical computation, and the use of digital computers equipped with formula manipulation compilers. When the tensor transformations are mechanised in the manner described, man-hours are saved and the errors to which human operators are prone can be avoided.

  13. Approximate relations and charts for low-speed stability derivatives of swept wings

    NASA Technical Reports Server (NTRS)

    Toll, Thomas A; Queijo, M J

    1948-01-01

    Contains derivations, based on a simplified theory, of approximate relations for low-speed stability derivatives of swept wings. Method accounts for the effects and, in most cases, taper ratio. Charts, based on the derived relations, are presented for the stability derivatives of untapered swept wings. Calculated values of the derivatives are compared with experimental results.

  14. Theoretical prediction of airplane stability derivatives at subcritical speeds

    NASA Technical Reports Server (NTRS)

    Tulinius, J.; Clever, W.; Nieman, A.; Dunn, K.; Gaither, B.

    1973-01-01

    The theoretical development and application is described of an analysis for predicting the major static and rotary stability derivatives for a complete airplane. The analysis utilizes potential flow theory to compute the surface flow fields and pressures on any configuration that can be synthesized from arbitrary lifting bodies and nonplanar thick lifting panels. The pressures are integrated to obtain section and total configuration loads and moments due side slip, angle of attack, pitching motion, rolling motion, yawing motion, and control surface deflection. Subcritical compressibility is accounted for by means of the Gothert similarity rule.

  15. Stability of coal-derived particles in organic media. [Ph. D Thesis on colloidal stability

    SciTech Connect

    Rodgers, B.R.

    1980-08-01

    Paraffins had previously been shown by a number of experimenters to produce agglomeration of particles in coal liquids. Microscopic examination of various solutions of the component classes with and without n-decane provided definitive evidence that agglomeration of solids did not occur in oils and resin solutions containing solids, unless asphaltenes were present. This observation provided early insight into the mechanism of agglomeration by adsorption of asphaltenes on particle surfaces. Empirical determinations of the stability of coal particle dispersions in pure hydrocarbon solvents were made by measuring their settling characteristics in solutions containing Aerosol OT (sodium di-2-ethyl-hexyl sulfosuccinate, commonly called AOT). Stability criteria for particles in aqueous electrolyte systems have been well established. A few authors have attempted an extrapolation to organic systems, generally concluding that, if significant charge exists, the stability criteria for aqueous systems can be used by taking into account the extended double layer of charge that exists in organic systems. With this consideration, the double layer repulsion-van der Waals attraction model indicates that the +24 mV charge on the coal-derived particles is sufficient for stability without the necessity to consider other factors such as steric hindrance. The zeta potentials measured herein were also shown to be related to the empirical stability as determined by settling characteristics. A mechanism for establishing the surface charge was developed based on conclusive observations from this work and is supported by the experiments of others. The proposed Coaloid model explains the high stability of particles in coal liquids. The stability of coal-derived materials during long-term storage was also an area of particular interest.

  16. Estimation of Stability and Control Derivatives of an F-15

    NASA Technical Reports Server (NTRS)

    Smith, Mark; Moes, Tim

    2006-01-01

    A technique for real-time estimation of stability and control derivatives (derivatives of moment coefficients with respect to control-surface deflection angles) was used to support a flight demonstration of a concept of an indirect-adaptive intelligent flight control system (IFCS). Traditionally, parameter identification, including estimation of stability and control derivatives, is done post-flight. However, for the indirect-adaptive IFCS concept, parameter identification is required during flight so that the system can modify control laws for a damaged aircraft. The flight demonstration was carried out on a highly modified F-15 airplane (see Figure 1). The main objective was to estimate the stability and control derivatives of the airplane in nearly real time. A secondary goal was to develop a system to automatically assess the quality of the results, so as to be able to tell a learning neural network which data to use. Parameter estimation was performed by use of Fourier-transform regression (FTR) a technique developed at NASA Langley Research Center. FTR is an equation- error technique that operates in the frequency domain. Data are put into the frequency domain by use of a recursive Fourier transform for a discrete frequency set. This calculation simplifies many subsequent calculations, removes biases, and automatically filters out data beyond the chosen frequency range. FTR as applied here was tailored to work with pilot inputs, which produce correlated surface positions that prevent accurate parameter estimates, by replacing half the derivatives with predicted values. FTR was also set up to work only on a recent window of data, to accommodate changes in flight condition. A system of confidence measures was developed to identify quality-parameter estimates that a learning neural network could use. This system judged the estimates primarily on the basis of their estimated variances and of the level of aircraft response. The resulting FTR system was implemented

  17. Polymer quantization, stability and higher-order time derivative terms

    NASA Astrophysics Data System (ADS)

    Cumsille, Patricio; Reyes, Carlos M.; Ossandon, Sebastian; Reyes, Camilo

    2016-03-01

    The possibility that fundamental discreteness implicit in a quantum gravity theory may act as a natural regulator for ultraviolet singularities arising in quantum field theory has been intensively studied. Here, along the same expectations, we investigate whether a nonstandard representation called polymer representation can smooth away the large amount of negative energy that afflicts the Hamiltonians of higher-order time derivative theories, rendering the theory unstable when interactions come into play. We focus on the fourth-order Pais-Uhlenbeck model which can be reexpressed as the sum of two decoupled harmonic oscillators one producing positive energy and the other negative energy. As expected, the Schrödinger quantization of such model leads to the stability problem or to negative norm states called ghosts. Within the framework of polymer quantization we show the existence of new regions where the Hamiltonian can be defined well bounded from below.

  18. Estimation of Rotary Stability Derivatives at Subsonic and Transonic Speeds

    NASA Technical Reports Server (NTRS)

    Tobak, Murray; Lessing, Henry C.

    1961-01-01

    The first part of this paper pertains to the estimation of subsonic rotary stability derivatives of wings. The unsteady potential flow problem is solved by a superposition of steady flow solutions. Numerical results for the damping coefficients of triangular wings are presented as functions of aspect ratio and Mach number, and are compared with experimental results over the Mach number range 0 to 1. In the second part, experimental results are used. to point out a close correlation between the nonlinear variations with angle of attack of the static pitching-moment curve slope and the damping-in-pitch coefficient. The underlying basis for the correlation is found as a result of an analysis in which the indicial function concept and. the principle of super-position are adapted to apply to the nonlinear problem. The form of the result suggests a method of estimating nonlinear damping coefficients from results of static wind-tunnel measurements.

  19. Stochastic stability of the derivative unscented Kalman filter

    NASA Astrophysics Data System (ADS)

    Hu, Gao-Ge; Gao, She-Sheng; Zhong, Yong-Min; Gao, Bing-Bing

    2015-07-01

    This is the second of two consecutive papers focusing on the filtering algorithm for a nonlinear stochastic discrete-time system with linear system state equation. The first paper established a derivative unscented Kalman filter (DUKF) to eliminate the redundant computational load of the unscented Kalman filter (UKF) due to the use of unscented transformation (UT) in the prediction process. The present paper studies the error behavior of the DUKF using the boundedness property of stochastic processes. It is proved that the estimation error of the DUKF remains bounded if the system satisfies certain conditions. Furthermore, it is shown that the design of the measurement noise covariance matrix plays an important role in improvement of the algorithm stability. The DUKF can be significantly stabilized by adding small quantities to the measurement noise covariance matrix in the presence of large initial error. Simulation results demonstrate the effectiveness of the proposed technique. Project supported by the National Natural Science Foundation of China (Grant No. 61174193) and the Doctorate Foundation of Northwestern Polytechnical University, China (Grant No. CX201409).

  20. Input design for identification of aircraft stability and control derivatives

    NASA Technical Reports Server (NTRS)

    Gupta, N. K.; Hall, W. E., Jr.

    1975-01-01

    An approach for designing inputs to identify stability and control derivatives from flight test data is presented. This approach is based on finding inputs which provide the maximum possible accuracy of derivative estimates. Two techniques of input specification are implemented for this objective - a time domain technique and a frequency domain technique. The time domain technique gives the control input time history and can be used for any allowable duration of test maneuver, including those where data lengths can only be of short duration. The frequency domain technique specifies the input frequency spectrum, and is best applied for tests where extended data lengths, much longer than the time constants of the modes of interest, are possible. These technqiues are used to design inputs to identify parameters in longitudinal and lateral linear models of conventional aircraft. The constraints of aircraft response limits, such as on structural loads, are realized indirectly through a total energy constraint on the input. Tests with simulated data and theoretical predictions show that the new approaches give input signals which can provide more accurate parameter estimates than can conventional inputs of the same total energy. Results obtained indicate that the approach has been brought to the point where it should be used on flight tests for further evaluation.

  1. Applications of Computational Methods for Dynamic Stability and Control Derivatives

    NASA Technical Reports Server (NTRS)

    Green, Lawrence L.; Spence, Angela M.

    2004-01-01

    Initial steps in the application o f a low-order panel method computational fluid dynamic (CFD) code to the calculation of aircraft dynamic stability and control (S&C) derivatives are documented. Several capabilities, unique to CFD but not unique to this particular demonstration, are identified and demonstrated in this paper. These unique capabilities complement conventional S&C techniques and they include the ability to: 1) perform maneuvers without the flow-kinematic restrictions and support interference commonly associated with experimental S&C facilities, 2) easily simulate advanced S&C testing techniques, 3) compute exact S&C derivatives with uncertainty propagation bounds, and 4) alter the flow physics associated with a particular testing technique from those observed in a wind or water tunnel test in order to isolate effects. Also presented are discussions about some computational issues associated with the simulation of S&C tests and selected results from numerous surface grid resolution studies performed during the course of the study.

  2. The Universal Plausibility Metric (UPM) & Principle (UPP)

    PubMed Central

    2009-01-01

    Background Mere possibility is not an adequate basis for asserting scientific plausibility. A precisely defined universal bound is needed beyond which the assertion of plausibility, particularly in life-origin models, can be considered operationally falsified. But can something so seemingly relative and subjective as plausibility ever be quantified? Amazingly, the answer is, "Yes." A method of objectively measuring the plausibility of any chance hypothesis (The Universal Plausibility Metric [UPM]) is presented. A numerical inequality is also provided whereby any chance hypothesis can be definitively falsified when its UPM metric of ξ is < 1 (The Universal Plausibility Principle [UPP]). Both UPM and UPP pre-exist and are independent of any experimental design and data set. Conclusion No low-probability hypothetical plausibility assertion should survive peer-review without subjection to the UPP inequality standard of formal falsification (ξ < 1). PMID:19958539

  3. Stability Characterization of Quinazoline Derivative BG1188 by Optical Methods

    NASA Astrophysics Data System (ADS)

    Militaru, Andra; Smarandache, Adriana; Mahamoud, Abdallah; Damian, Victor; Ganea, Paul; Alibert, Sandrine; Pagès, Jean-Marie; Pascu, Mihail-Lucian

    2011-08-01

    3-[2-(dimethylamino)ethyl]-6-nitroquinazolin-4(3H)-one, labeled BG1188, is a new synthesized compound, out of a series of quinazoline derivatives developed to fight the multidrug resistance of antibiotics acquired by bacteria. A characterization of the BG1188 powder was made using FTIR spectra in order to evidence the functional groups in the medicine's molecule. The ultraviolet-visible (UV-Vis) absorption spectra were used to study the stability of the BG1188 solutions in two solvents and at different temperatures. BG1188 concentration in ultrapure water was varied between 2×10-3 M (stock solution) and 10-6 M. The concentration recommended by higher activity on bacteria was 10-3 M. For the same reason, this was the utilized concentration of BG1188 in dimethyl sulfoxide (DMSO). Time stability was characterized by comparing the time evolution of the UV-Vis absorption spectra of the BG1188 solutions in ultrapure de-ionized water or in DMSO. The spectra were recorded daily for about 4 months after the preparation for the BG1188 solutions in ultrapure water. Generally, samples are stable within the experimental errors at concentrations higher than 10-5 M, but the stability time interval may vary from 119 days at 10-4 M to 34 days at 10-5 M. Time evolution of the absorption spectra at 10-3 M in ultrapure water shows reproducibility within the measuring errors (±1.045%) for time intervals up to 1032 hours (more than 40 days) after preparation. On the other hand, BG1188 solutions in DMSO may be considered unstable because the absorption spectra modify in terms of peak shapes and intensities, indicating that the samples exhibit modifications immediately after preparation. Regardless the solvent used, some aggregation phenomena took place and wire-like aggregates were observed in all the solutions with the naked eye. These aggregates were analyzed, tentatively, using optical microscopy and FTIR.

  4. Proton stability and light Z' inspired by string derived models

    SciTech Connect

    Faraggi, Alon E.; Mehta, Viraf M.

    2011-10-15

    Proton stability is one of the most perplexing puzzles in particle physics. While the renormalizable standard model forbids proton decay mediating operators due to accidental global symmetries, many of its extensions introduce such dimension four, five and six operators. Furthermore, it is, in general, expected that quantum gravity only respects local gauge, or discreet, symmetries. String theory provides the arena to study particle physics in a consistent framework of perturbative quantum gravity. An appealing proposition, in this context, is that the dangerous operators are suppressed by an Abelian gauge symmetry, which is broken near the TeV scale. A viable U(1) symmetry should also be anomaly free, be family universal, and allow the generation of fermion masses via the Higgs mechanism. We discuss such U(1) symmetries that arise in quasirealistic free fermionic heterotic-string derived models. Ensuring that the U(1) symmetry is anomaly free at the low scale requires that the standard model spectrum is augmented by additional states that are compatible with the charge assignments in the string models. We construct such string-inspired models and discuss some of their phenomenological implications.

  5. Effects of Plausibility on Structural Priming

    ERIC Educational Resources Information Center

    Christianson, Kiel; Luke, Steven G.; Ferreira, Fernanda

    2010-01-01

    We report a replication and extension of Ferreira (2003), in which it was observed that native adult English speakers misinterpret passive sentences that relate implausible but not impossible semantic relationships (e.g., "The angler was caught by the fish") significantly more often than they do plausible passives or plausible or implausible…

  6. Matrix methods for determining the longitudinal-stability derivatives of an airplane from transient flight data

    NASA Technical Reports Server (NTRS)

    Donegan, James J

    1954-01-01

    Three matrice methods are developed and presented for determining the longitudinal-stability derivatives from transient flight data. In these methods the expressions for some of the stability derivatives are in the form generally used in stability calculations. The first method requires the combination of four measurements in time-history form, two of which must be incremental elevator deflection and incremental tail load and the other two measurements can be chosen from a possible three, namely incremental load factor, pitching velocity, and angle of attack. The method demonstrates the use of the tail load to separate the pitching-moment derivatives and to determine the downwash derivative. (author)

  7. Analytic models of plausible gravitational lens potentials

    SciTech Connect

    Baltz, Edward A.; Marshall, Phil; Oguri, Masamune E-mail: pjm@physics.ucsb.edu

    2009-01-15

    Gravitational lenses on galaxy scales are plausibly modelled as having ellipsoidal symmetry and a universal dark matter density profile, with a Sersic profile to describe the distribution of baryonic matter. Predicting all lensing effects requires knowledge of the total lens potential: in this work we give analytic forms for that of the above hybrid model. Emphasising that complex lens potentials can be constructed from simpler components in linear combination, we provide a recipe for attaining elliptical symmetry in either projected mass or lens potential. We also provide analytic formulae for the lens potentials of Sersic profiles for integer and half-integer index. We then present formulae describing the gravitational lensing effects due to smoothly-truncated universal density profiles in cold dark matter model. For our isolated haloes the density profile falls off as radius to the minus fifth or seventh power beyond the tidal radius, functional forms that allow all orders of lens potential derivatives to be calculated analytically, while ensuring a non-divergent total mass. We show how the observables predicted by this profile differ from that of the original infinite-mass NFW profile. Expressions for the gravitational flexion are highlighted. We show how decreasing the tidal radius allows stripped haloes to be modelled, providing a framework for a fuller investigation of dark matter substructure in galaxies and clusters. Finally we remark on the need for finite mass halo profiles when doing cosmological ray-tracing simulations, and the need for readily-calculable higher order derivatives of the lens potential when studying catastrophes in strong lenses.

  8. Analytic Models of Plausible Gravitational Lens Potentials

    SciTech Connect

    Baltz, Edward A.; Marshall, Phil; Oguri, Masamune

    2007-05-04

    Gravitational lenses on galaxy scales are plausibly modeled as having ellipsoidal symmetry and a universal dark matter density profile, with a Sersic profile to describe the distribution of baryonic matter. Predicting all lensing effects requires knowledge of the total lens potential: in this work we give analytic forms for that of the above hybrid model. Emphasizing that complex lens potentials can be constructed from simpler components in linear combination, we provide a recipe for attaining elliptical symmetry in either projected mass or lens potential.We also provide analytic formulae for the lens potentials of Sersic profiles for integer and half-integer index. We then present formulae describing the gravitational lensing effects due to smoothly-truncated universal density profiles in cold dark matter model. For our isolated haloes the density profile falls off as radius to the minus fifth or seventh power beyond the tidal radius, functional forms that allow all orders of lens potential derivatives to be calculated analytically, while ensuring a non-divergent total mass. We show how the observables predicted by this profile differ from that of the original infinite-mass NFW profile. Expressions for the gravitational flexion are highlighted. We show how decreasing the tidal radius allows stripped haloes to be modeled, providing a framework for a fuller investigation of dark matter substructure in galaxies and clusters. Finally we remark on the need for finite mass halo profiles when doing cosmological ray-tracing simulations, and the need for readily-calculable higher order derivatives of the lens potential when studying catastrophes in strong lenses.

  9. What can we learn from Plausible Values?

    PubMed

    Marsman, Maarten; Maris, Gunter; Bechger, Timo; Glas, Cees

    2016-06-01

    In this paper, we show that the marginal distribution of plausible values is a consistent estimator of the true latent variable distribution, and, furthermore, that convergence is monotone in an embedding in which the number of items tends to infinity. We use this result to clarify some of the misconceptions that exist about plausible values, and also show how they can be used in the analyses of educational surveys. PMID:27052959

  10. Stability of Biomass-derived Black Carbon in Soils

    SciTech Connect

    Liang, Biqing; Lehmann, Johannes C.; Solomon, Dawit; Sohi, Saran; Thies, Janice E.; Skjemstad, Jan O.; Luizao, Flavio J.; Engelhard, Mark H.; Neves, Eduaro G.; Wirick, Sue

    2008-12-15

    Black carbon (BC) may play an important role in the global C budget, due to its potential to act as a significant removal (sink) of atmospheric CO2. In order to fully evaluate the influence of BC on the global C cycle, a sound understanding of the stability of BC is required. The biochemical stability of BC was assessed in a chronosequence of high-BC containing Anthrosols from the central Amazon, Brazil, using a range of spectroscopic and biological methods. Results revealed that the Anthrosols had 61-80% lower (P<0.05) CO2 evolution over 532 days compared to that in the corresponding adjacent soils with low BC contents. No significant (P>0.05) differences of CO2 respiration were observed between Anthrosols with contrasting ages of BC and soil textures. Molecular forms of core regions of micrometer-sized BC particles quantified by synchrotron-based near-edge x-ray fine structure (NEXAFS) spectroscopy coupled to scanning x-ray transmission microscopy (STXM) remained similar regardless of their ages (600 to 8,700 years) and closely resembled the spectral characteristics of fresh BC. Deconvolution of NEXAFS spectra revealed greater oxidation on the surfaces of BC particles with little penetration into the core of the particles. The similar C mineralization between different BC-rich soils regardless of soil texture underpins the importance of chemical recalcitrance for the stability of BC, in contrast to adjacent soils which showed the highest mineralization in the sandiest soil. However, C distribution between free, intra-aggregate and organo-mineral pools was significantly different between soils with high and low BC contents, suggesting some degree of physical stabilization, and BC-rich Anthrosols had higher proportions (72-90%) of C in the organo-mineral fraction than BC-poor adjacent soils (2-70%).

  11. C60-derived nanobaskets: stability, vibrational signatures, and molecular trapping.

    PubMed

    dos Santos, S G; Pires, M S; Lemos, V; Freire, V N; Caetano, E W S; Galvão, D S; Sato, F; Albuquerque, E L

    2009-09-30

    C(60)-derived nanobaskets, with chemical formulae (symmetry point group) C(40)H(10) (C(5v)), C(39)H(12) (C(3v)), C(46)H(12) (C(2v)), were investigated. Molecular dynamic simulations (MDSs) indicate that the molecules preserve their bonding frame for temperatures up to 300 K (simulation time 100 ps), and maintain atomic cohesion for at least 4 ps at temperatures up to 3500 K. The infrared spectra of the C(60)-derived nanobaskets were simulated through density functional theory (DFT) calculations, allowing for the attribution of infrared signatures specific to each carbon nanobasket. The possibility of using C(60)-derived nanobaskets as molecular containers is demonstrated by performing a DFT study of their bonding to hydrogen, water, and L-alanine. The carbon nanostructures presented here show a higher bonding energy (approximately 1.0 eV), suggesting that a family of nanostructures, C(n)-derived (n = 60,70,76,80, etc) nanobaskets, could work as molecular containers, paving the way for future developments such as tunable traps for complex molecular systems. PMID:19724106

  12. Yield stability in genotypes derived through basic breeding

    Technology Transfer Automated Retrieval System (TEKTRAN)

    The sugarcane variety ‘LCP 85-384’ was derived through basic (introgression) breeding, and after its release in 1995, the variety quickly gained acreage in the state of Louisiana. The primary reason for the popularity of the variety was the plant vigor and increase in the number of ratoon harvests ...

  13. Improved plausibility bounds about the 2005 HIV and AIDS estimates

    PubMed Central

    Morgan, M; Walker, N; Gouws, E; Stanecki, K A; Stover, J

    2006-01-01

    Background Since 1998 the Joint United Nations Programme on HIV/AIDS and the World Health Organization has provided estimates on the magnitude of the HIV epidemic for individual countries. Starting with the 2003 estimates, plausibility bounds about the estimates were also reported. The bounds are intended to serve as a guide as to what reasonable or plausible ranges are for the uncertainty in HIV incidence, prevalence, and mortality. Methods Plausibility bounds were developed for three situations: for countries with generalised epidemics, for countries with low level or concentrated epidemics (LLC), and for regions. The techniques used build on those developed for the previous reporting round. However the current bounds are based on the available surveillance and survey data from each individual country rather than on data from a few prototypical countries. Results The uncertainty around the HIV estimates depends on the quality of the surveillance system in the country. Countries with population based HIV seroprevalence surveys have the tightest plausibility bounds (average relative range about the adult HIV prevalence (ARR) of −18% to +19%.) Generalised epidemic countries without a survey have the next tightest ranges (average ARR of −46% to +59%). Those LLC countries which have conducted multiple surveys over time for HIV among the populations most at risk have the bounds similar to those in generalised epidemic countries (ARR −40% to +67%). As the number and quality of the studies in LLC countries goes down, the plausibility bounds increase (ARR of −38% to +102% for countries with medium quality data and ARR of −53% to +183% for countries with poor quality data). The plausibility bounds for regions directly reflect the bounds for the countries in those regions. Conclusions Although scientific, the plausibility bounds do not represent and should not be interpreted as formal statistical confidence intervals. However in order to make the bounds as

  14. Lateral stability and control derivatives extracted from space shuttle Challenger flight data

    NASA Technical Reports Server (NTRS)

    Schiess, James R.

    1988-01-01

    Flight data taken from six flights of the Space Transportation System shuttle Challenger (STS-6, 7, 8, 11, 13 and 17) during atmospheric entry are analyzed to determine the shuttle lateral aerodynamic characteristics. Maximum likelihood estimation is applied to data derived from accelerometer and rate gyro measurements and trajectory, meteorological and control surface data to estimate lateral-directional stability and control derivatives. The vehicle stability and control surface effectiveness are compared across the flights and to preflight predicted values.

  15. MODIS thermal emissive band calibration stability derived from surface targets

    NASA Astrophysics Data System (ADS)

    Wenny, B. N.; Xiong, X.; Dodd, J.

    2009-09-01

    The 16 MODIS Thermal Emissive Bands (TEB), with wavelengths covering from 3.7μm to 14.4μm, are calibrated using scan-by-scan observations of an on-orbit blackbody (BB). Select Earth surface targets can be used to track the long-term consistency, stability and relative bias between the two MODIS instruments currently in orbit. Measurements at Dome C, Antarctica have shown a relative bias of less than 0.01K over a 5 year period between Terra and Aqua MODIS Band 31 (11μm). Dome C surface temperatures are typically outside the MODIS BB calibration range. Sea surface temperature (SST) measurements from data buoys provide a useful reference at higher scene temperatures. This paper extends the techniques previously applied only to Band 31 to the remaining TEB using both Dome C and SST sites. The long-term calibration stability and relative bias between Terra and Aqua MODIS is discussed.

  16. Correlation of Predicted and Flight Derived Stability and Control Derivatives with Particular Application to Tailless Delta Wing Configurations

    NASA Technical Reports Server (NTRS)

    Weil, J.

    1981-01-01

    Flight derived longitudinal and lateral-directional stability and control derivatives were compared to wind-tunnel derived values. As a result of these comparisons, boundaries representing the uncertainties that could be expected from wind-tunnel predictions were established. These boundaries provide a useful guide for control system sensitivity studies prior to flight. The primary application for this data was the space shuttle, and as a result the configurations included in the study were those most applicable to the space shuttle. The configurations included conventional delta wing aircraft as well as the X-15 and lifting body vehicles.

  17. Stability and control derivative estimates obtained from flight data for the Beech 99 aircraft

    NASA Technical Reports Server (NTRS)

    Tanner, R. R.; Montgomery, T. D.

    1979-01-01

    Lateral-directional and longitudinal stability and control derivatives were determined from flight data by using a maximum likelihood estimator for the Beech 99 airplane. Data were obtained with the aircraft in the cruise configuration and with one-third flap deflection. The estimated derivatives show good agreement with the predictions of the manufacturer.

  18. Analytical study to define a helicoper stability derivative extraction method, volume 2

    NASA Technical Reports Server (NTRS)

    Molusis, J. A.

    1973-01-01

    The data generated during tests to determine helicopter stability derivatives are presented in the form of graphs. The data are based on CH-53A helicopters and CH-54B helicopters with various digital filters operating at various airspeeds. Curves are plotted for a time history comparison of identified derivative models against flight data for the helicopters at specific airspeeds and maneuvers.

  19. Differential Mitotic Stability of Yeast Disomes Derived from Triploid Meiosis

    PubMed Central

    Campbell, Douglas; Doctor, John S.; Feuersanger, Jeane H.; Doolittle, Mark M.

    1981-01-01

    The frequencies of recovered disomy among the meiotic segregants of yeast (Saccharomyces cerevisiae) triploids were assessed under conditions in which all 17 yeast chromosomes were monitored simultaneously. The studies employed inbred triploids, in which all homologous centromeres were identical by descent, and single haploid testers carrying genetic markers for all 17 linkage groups. The principal results include: (1) Ascospores from triploid meiosis germinate at frequencies comparable to those from normal diploids, but most fail to produce visible colonies due to the growth-retarding effects of high multiple disomy. (2) The probability of disome formation during triploid meiosis is the same for all chromosomes; disomy for any given chromosome does not exclude simultaneous disomy for any other chromosome. (3) The 17 yeast chromosomes fall into three frequency classes in terms of disome recovery. The results support the idea that multiply disomic meiotic segregants of the triploid experience repeated, nonrandom, post-germination mitotic chromosome losses (N+1→N) and that the observed variations in individual disome recovery are wholly attributable to inherent differences in disome mitotic stability. PMID:7035289

  20. Steady-State Computation of Constant Rotational Rate Dynamic Stability Derivatives

    NASA Technical Reports Server (NTRS)

    Park, Michael A.; Green, Lawrence L.

    2000-01-01

    Dynamic stability derivatives are essential to predicting the open and closed loop performance, stability, and controllability of aircraft. Computational determination of constant-rate dynamic stability derivatives (derivatives of aircraft forces and moments with respect to constant rotational rates) is currently performed indirectly with finite differencing of multiple time-accurate computational fluid dynamics solutions. Typical time-accurate solutions require excessive amounts of computational time to complete. Formulating Navier-Stokes (N-S) equations in a rotating noninertial reference frame and applying an automatic differentiation tool to the modified code has the potential for directly computing these derivatives with a single, much faster steady-state calculation. The ability to rapidly determine static and dynamic stability derivatives by computational methods can benefit multidisciplinary design methodologies and reduce dependency on wind tunnel measurements. The CFL3D thin-layer N-S computational fluid dynamics code was modified for this study to allow calculations on complex three-dimensional configurations with constant rotation rate components in all three axes. These CFL3D modifications also have direct application to rotorcraft and turbomachinery analyses. The modified CFL3D steady-state calculation is a new capability that showed excellent agreement with results calculated by a similar formulation. The application of automatic differentiation to CFL3D allows the static stability and body-axis rate derivatives to be calculated quickly and exactly.

  1. Another Look At The Canon of Plausible Inference

    NASA Astrophysics Data System (ADS)

    Solana-Ortega, Alberto; Solana, Vicente

    2005-11-01

    Systematic study of plausible inference is very recent. Axiomatics have been traditionally limited to the development of uninterpreted pure calculi for comparing individual inferences, ignoring the need of formalisms to solve each of these inferences and leaving the interpretation and application of such calculi to ad hoc statistical criteria which are open to inconsistencies. Here we defend a different viewpoint, regarding plausible inference in a holistic manner. Specifically we consider that all tasks involved in it, including the formalization of languages in which to pose problems, the definitions and axiomatics leading to calculation rules and those for deriving inference procedures or assignment rules, ought to be based on common grounds. For this purpose a set of elementary requirements establishing desirable properties so fundamental any theory of scientific inference should satisfy is proposed under the name of plausible inference canon. Its logical status as an extramathematical foundation is investigated, together with the different roles it plays as constructive guideline, standard for contrasting frameworks or normative stipulation. We also highlight the novelties it introduces with respect to similar proposals by other authors. In particular we concentrate on those aspects of the canon related to the critical issue of adequately incorporating basic evidential knowledge to inference.

  2. Some effects of nonlinear variation in the directional-stability and damping-in-yawing derivatives on the lateral stability of an airplane

    NASA Technical Reports Server (NTRS)

    Sternfield, Leonard

    1951-01-01

    A theoretical investigation has been made to determine the effect of nonlinear stability derivatives on the lateral stability of an airplane. Motions were calculated on the assumption that the directional-stability and the damping-in-yawing derivatives are functions of the angle of sideslip. The application of the Laplace transform to the calculation of an airplane motion when certain types of nonlinear derivatives are present is described in detail. The types of nonlinearities assumed correspond to the condition in which the values of the directional-stability and damping-in-yawing derivatives are zero for small angle of sideslip.

  3. Determination of Stability and Control Derivatives using Computational Fluid Dynamics and Automatic Differentiation

    NASA Technical Reports Server (NTRS)

    Park, Michael A.; Green, Lawrence L.; Montgomery, Raymond C.; Raney, David L.

    1999-01-01

    With the recent interest in novel control effectors there is a need to determine the stability and control derivatives of new aircraft configurations early in the design process. These derivatives are central to most control law design methods and would allow the determination of closed-loop control performance of the vehicle. Early determination of the static and dynamic behavior of an aircraft may permit significant improvement in configuration weight, cost, stealth, and performance through multidisciplinary design. The classical method of determining static stability and control derivatives - constructing and testing wind tunnel models - is expensive and requires a long lead time for the resultant data. Wind tunnel tests are also limited to the preselected control effectors of the model. To overcome these shortcomings, computational fluid dynamics (CFD) solvers are augmented via automatic differentiation, to directly calculate the stability and control derivatives. The CFD forces and moments are differentiated with respect to angle of attack, angle of sideslip, and aircraft shape parameters to form these derivatives. A subset of static stability and control derivatives of a tailless aircraft concept have been computed by two differentiated inviscid CFD codes and verified for accuracy with central finite-difference approximations and favorable comparisons to a simulation database.

  4. Effects of time-shifted data on flight determined stability and control derivatives

    NASA Technical Reports Server (NTRS)

    Steers, S. T.; Iliff, K. W.

    1975-01-01

    Flight data were shifted in time by various increments to assess the effects of time shifts on estimates of stability and control derivatives produced by a maximum likelihood estimation method. Derivatives could be extracted from flight data with the maximum likelihood estimation method even if there was a considerable time shift in the data. Time shifts degraded the estimates of the derivatives, but the degradation was in a consistent rather than a random pattern. Time shifts in the control variables caused the most degradation, and the lateral-directional rotary derivatives were affected the most by time shifts in any variable.

  5. Biologically Plausible, Human-Scale Knowledge Representation.

    PubMed

    Crawford, Eric; Gingerich, Matthew; Eliasmith, Chris

    2016-05-01

    Several approaches to implementing symbol-like representations in neurally plausible models have been proposed. These approaches include binding through synchrony (Shastri & Ajjanagadde, ), "mesh" binding (van der Velde & de Kamps, ), and conjunctive binding (Smolensky, ). Recent theoretical work has suggested that most of these methods will not scale well, that is, that they cannot encode structured representations using any of the tens of thousands of terms in the adult lexicon without making implausible resource assumptions. Here, we empirically demonstrate that the biologically plausible structured representations employed in the Semantic Pointer Architecture (SPA) approach to modeling cognition (Eliasmith, ) do scale appropriately. Specifically, we construct a spiking neural network of about 2.5 million neurons that employs semantic pointers to successfully encode and decode the main lexical relations in WordNet, which has over 100,000 terms. In addition, we show that the same representations can be employed to construct recursively structured sentences consisting of arbitrary WordNet concepts, while preserving the original lexical structure. We argue that these results suggest that semantic pointers are uniquely well-suited to providing a biologically plausible account of the structured representations that underwrite human cognition. PMID:26173464

  6. A summary of lateral-stability derivatives calculated for wing plan forms in supersonic flow

    NASA Technical Reports Server (NTRS)

    Jones, Arthur L; Alksne, Alberta

    1951-01-01

    A compilation of theoretical values of the lateral-stability derivatives for wings at supersonic speeds is presented in the form of design charts. The wing plan forms for which this compilation has been prepared include a rectangular, two trapezoidal, two triangular, a fully-tapered swept-back, a sweptback hexagonal, an unswept hexagonal, and a notched triangular plan form. A full set of results, that is, values for all nine of the lateral-stability derivatives for wings, was available for the first six of these plan forms only. The reasons for the incompleteness of the results available for other plan forms are discussed.

  7. Specific stability region analysis for uncertain fuzzy descriptor systems with multiple derivative matrices

    NASA Astrophysics Data System (ADS)

    Huang, Chih-Peng

    2016-06-01

    This paper addresses the specific stability region for uncertain fuzzy descriptor systems with distinct derivative matrices in the rules. First, an equivalent poles' location criterion for the nominal descriptor system is originally derived and expressed as one compact form of strict and complex linear matrix inequality (LMI). Then, the result can be extended to cope with the specific stability region for the uncertain fuzzy descriptor systems with integrating multiple derivative matrices. Moreover, since the presented criteria involve complex LMIs, we appropriately conduct a projection scheme, where current LMI tools cannot evaluate them. By deriving useful projection operators onto the formed convex sets, an analysing algorithm is consequently presented for numerical evaluation. Finally, three numerical examples, two nonlinear systems and a physical circuit system, are given to demonstrate the validity and the practicability of the proposed approach.

  8. Nutritional stability of various naturally occurring monoglutamate derivatives of folic acid.

    PubMed

    O'Broin, J D; Temperley, I J; Brown, J P; Scott, J M

    1975-05-01

    The nutritional stabilities of four major dietary folates were studied as their corresponding monoglutamates and were compared to pteroylglutamate (folic acid) itself. The study of the monoglutamyl rather than polyglutamyl forms was justified since the former are formed during the course of digestion and also addition of extra glutamyl residues is unlikely to affect the types of nutritional instability associated with these derivatives. Since ability to support growth in Lactobacillus casei is known to reflect nutritional activity in man this organism was used in the stability studies. It was found that pteroylglutamate and 5-formyltetrahydropteroylglutamate had nutritional stabilities of the order of weeks although the stability of the former was decreased by phosphate. Surprisingly 10-formyltetrahydropteroylglutamate was nutritionally more stable than expected, possibly due to its conversion to the more stable oxidized 10-formylpteroylglutamate or to the reduced 5-formyl derivative. In contrast 5-methyltetrahydropteroylglutamate was much less stable nutritionally than expected.Unsubstituted tetrahydropteroylglutamate was most unstable nutritionally but in contrast to the other derivatives examined it was more stable under acidic than basic conditions. Ascorbate was found to be a far superior stabilizing agent than 2-mercaptoethanol at comparable concentrations. PMID:236647

  9. Effect of sampling rate and record length on the determination of stability and control derivatives

    NASA Technical Reports Server (NTRS)

    Brenner, M. J.; Iliff, K. W.; Whitman, R. K.

    1978-01-01

    Flight data from five aircraft were used to assess the effects of sampling rate and record length reductions on estimates of stability and control derivatives produced by a maximum likelihood estimation method. Derivatives could be extracted from flight data with the maximum likelihood estimation method even if there were considerable reductions in sampling rate and/or record length. Small amplitude pulse maneuvers showed greater degradation of the derivative maneuvers than large amplitude pulse maneuvers when these reductions were made. Reducing the sampling rate was found to be more desirable than reducing the record length as a method of lessening the total computation time required without greatly degrading the quantity of the estimates.

  10. Longitudinal stability and control derivatives obtained from flight data of a PA-30 aircraft

    NASA Technical Reports Server (NTRS)

    Turley, D. R.; Sandlin, D. R.

    1981-01-01

    In order to obtain reliable and accurate values of the stability and control derivatives, the Dryden Fligh Research Center (DFRC) developed a technique for extracting the derivatives from flight data. This technique is implemented by a set of FORTRAN computer programs that is based on a modified maximum likelihood estimator that uses the Newton-Raphson algorithm to perform the required minimization of the derivatives. Data was obtained with a PA-30, light twin-engine general aviation aircraft in zero, half, and full flap configuration in level unaccelerated flight with the landing gear retracted. The derivatives were plotted as functions of angle of attack using various graphical arrangements to show variations of wind tunnel and flight determined values at zero flap settings. Also, data was displayed to show the effects of flap deflection and thrust variation on the longitudinal stability derivatives. The angle of attack and angle of sideslip were measured. The dynamic pressure, velocity, and altitude were calculated, using a FORTRAN computer program, from the static and dynamic pressures. The control deflections of the stabilator, ailerons, and rudder also were recorded along with left throttle position, engine rpm, and manifold pressure.

  11. Solid dispersion of quercetin in cellulose derivative matrices influences both solubility and stability.

    PubMed

    Li, Bin; Konecke, Stephanie; Harich, Kim; Wegiel, Lindsay; Taylor, Lynne S; Edgar, Kevin J

    2013-02-15

    Amorphous solid dispersions (ASD) of quercetin (Que) in cellulose derivative matrices, carboxymethylcellulose acetate butyrate (CMCAB), hydroxypropylmethylcellulose acetate succinate (HPMCAS), and cellulose acetate adipate propionate (CAAdP) were prepared with the goal of identifying an ASD that effectively increased Que aqueous solution concentration. Crystalline quercetin and Que/poly(vinylpyrrolidinone) (PVP) ASD were evaluated for comparison. Powder X-ray diffraction (XRPD) and differential scanning calorimetry (DSC) were used to examine the crystallinity of ASDs, physical mixtures (PM) and quercetin. ASDs were amorphous up to 50 wt% Que. Que stability against crystallization and solution concentrations from these ASDs were significantly higher than those observed for physical mixtures and crystalline Que. PVP stabilizes against both Que degradation and recrystallization; in contrast, these carboxylated cellulose derivatives inhibit recrystallization but release Que slowly. PVP ASDs afforded fast and complete drug release, while ASDs using these three cellulose derivatives provide slow, incomplete, pH-triggered drug release. PMID:23399255

  12. Selected stability and control derivatives from the first Space Shuttle entry

    NASA Technical Reports Server (NTRS)

    Iliff, K. W.; Maine, R. E.; Cooke, D. R.

    1981-01-01

    Primary stability and control derivative estimates garnered from the first Shuttle entry are reported. The craft was the first vehicle to maneuver over a wide range of hypersonic velocities, yielding data on flight characteristics from previously unexplored regimes. The flight envelope was confined to entry and safe landing, with no additional maneuvers to gain control data. Data for a Mach number range of 25-1.5 and altitudes of 515,000-50,000 ft are provided, and functional ranges of the Shuttle control surfaces and attitude jets are outlined. On-board systems gathered data on aerodynamic coefficient identification, flight condition and Euler angles, and jet chamber pressures. A maximum likelihood estimation program, which contained unknown stability and control derivatives, was used for control; a control input determined the value of the unknown derivatives, and the input and spacecraft response were measured. Longitudinal and lateral directional maneuvers and their derivative estimates are described, noting wind contamination of the sideslip measurements below Mach 3. Further maneuvering and stability tests are projected for subsequent flights.

  13. Higher derivative extensions of 3 d Chern-Simons models: conservation laws and stability

    NASA Astrophysics Data System (ADS)

    Kaparulin, D. S.; Karataeva, I. Yu.; Lyakhovich, S. L.

    2015-11-01

    We consider the class of higher derivative 3 d vector field models with the field equation operator being a polynomial of the Chern-Simons operator. For the nth-order theory of this type, we provide a general recipe for constructing n-parameter family of conserved second rank tensors. The family includes the canonical energy-momentum tensor, which is unbounded, while there are bounded conserved tensors that provide classical stability of the system for certain combinations of the parameters in the Lagrangian. We also demonstrate the examples of consistent interactions which are compatible with the requirement of stability.

  14. Invariant visual object recognition: biologically plausible approaches.

    PubMed

    Robinson, Leigh; Rolls, Edmund T

    2015-10-01

    Key properties of inferior temporal cortex neurons are described, and then, the biological plausibility of two leading approaches to invariant visual object recognition in the ventral visual system is assessed to investigate whether they account for these properties. Experiment 1 shows that VisNet performs object classification with random exemplars comparably to HMAX, except that the final layer C neurons of HMAX have a very non-sparse representation (unlike that in the brain) that provides little information in the single-neuron responses about the object class. Experiment 2 shows that VisNet forms invariant representations when trained with different views of each object, whereas HMAX performs poorly when assessed with a biologically plausible pattern association network, as HMAX has no mechanism to learn view invariance. Experiment 3 shows that VisNet neurons do not respond to scrambled images of faces, and thus encode shape information. HMAX neurons responded with similarly high rates to the unscrambled and scrambled faces, indicating that low-level features including texture may be relevant to HMAX performance. Experiment 4 shows that VisNet can learn to recognize objects even when the view provided by the object changes catastrophically as it transforms, whereas HMAX has no learning mechanism in its S-C hierarchy that provides for view-invariant learning. This highlights some requirements for the neurobiological mechanisms of high-level vision, and how some different approaches perform, in order to help understand the fundamental underlying principles of invariant visual object recognition in the ventral visual stream. PMID:26335743

  15. Comprehending Conflicting Science-Related Texts: Graphs as Plausibility Cues

    ERIC Educational Resources Information Center

    Isberner, Maj-Britt; Richter, Tobias; Maier, Johanna; Knuth-Herzig, Katja; Horz, Holger; Schnotz, Wolfgang

    2013-01-01

    When reading conflicting science-related texts, readers may attend to cues which allow them to assess plausibility. One such plausibility cue is the use of graphs in the texts, which are regarded as typical of "hard science." The goal of our study was to investigate the effects of the presence of graphs on the perceived plausibility and…

  16. Thermal stability and refolding capability of shark derived single domain antibodies.

    PubMed

    Liu, Jinny L; Zabetakis, Dan; Brown, Jazmine C; Anderson, George P; Goldman, Ellen R

    2014-06-01

    Single-domain antibodies (sdAb) from camelids and sharks represent the smallest immunoglobulin-based functional binding domains, and are known for their thermal stability and ability to refold after denaturation. Whereas target-binding sdAb have been derived from both immunized and naïve sharks and camelids, the stability of camelid-derived sdAb have been evaluated much more extensively. To address this disparity we characterized 20 sdAb derived from spiny dogfish shark and smooth dogfish shark in terms of their protein production, melting temperature and ability to refold after heat denaturation. Using the same expression system and protocol as we follow to produce camelid sdAb, production of the shark sdAb was quite poor, often resulting in less than a tenth of the typical yield for camelid sdAb. We measured the melting temperature of each of the sdAb. Similar to camelid sdAb, the shark-derived sdAb, showed a range of melting temperature values from 42°C to 77°C. Also similar to what has been observed in camelids, the sdAb from both shark species showed a range of ability to refold after heat denaturation. This work demonstrated that although shark sdAb can possess high melting temperatures and refolding ability, no clear advantage over sdAb derived from camelids in terms of thermostability and renaturation was obtained. PMID:24667069

  17. Nonminimal derivative coupling scalar-tensor theories: Odd-parity perturbations and black hole stability

    NASA Astrophysics Data System (ADS)

    Cisterna, Adolfo; Cruz, Miguel; Delsate, Térence; Saavedra, Joel

    2015-11-01

    We derive the odd-parity perturbation equation for the nonminimal kinetic coupling sector of the general Horndeski theory, where the kinetic term is coupled to the metric and the Einstein tensor. We derive the potential of the perturbation, by identifying a master function and switching to tortoise coordinates. We then prove the mode stability under linear odd-parity perturbations of hairy black holes in this sector of Horndeski theory, when a cosmological constant term in the action is included. Finally, we comment on the existence of slowly rotating black hole solutions in this setup and discuss their implications on the physics of compact object configurations, such as neutron stars.

  18. Effects of heteroatoms of tetracene and pentacene derivatives on their stability and singlet fission.

    PubMed

    Chen, Yuhan; Shen, Li; Li, Xiyou

    2014-07-31

    The effects of the introduction of an sp(2)-hybridized nitrogen atom (═N-) and thiophene ring on the structure geometries, frontier molecular orbital energies, and excited state energies related to singlet fission (SF) for some tetracene and pentacene derivatives were theoretically investigated by quantum chemical methods. The introduction of a nitrogen atom significantly decreases the energies of frontier molecular orbitals and hence improves their stabilities in air and light illumination. More importantly, it is helpful for reducing the energy loss of the exothermic singlet fission of pentacene derivatives. For fused benzene-thiophene structures, the (α, β) connection pattern could stabilize the frontier molecular orbitals, while the (β, β) connection pattern can promote the thermodynamic driving force of singlet fission. These facts provide a theoretical ground for rational design of SF materials. PMID:25007000

  19. Shuttle entry performance and stability and control derivatives extraction from flight measurement data

    NASA Technical Reports Server (NTRS)

    Compton, H. R.; Scallion, W. I.; Schiess, J. R.; Suit, W. T.

    1982-01-01

    Flight data taken from three Shuttle Space Transportation System flights (STS-1, 2, and 3) during entry are analyzed to determine the shuttle performance and aerodynamic characteristics. Correlations of the performance coefficients and the stability and control derivatives with preflight predictions are presented over the hypersonic speed range from Mach 2 to 25. In addition, an evaluation of the effectiveness of the onboard Reaction Control System (RCS) is given and an effort is made to independently quantify the combined impingement and flow-field interaction effects on the spacecraft rolling moment. Comparisons of stability and control derivatives extracted for the same flight conditions, but using data from different onboard sensors are also made. Results obtained using the same flight data, but different computer software are also shown.

  20. Development of Small-Molecule Cryptochrome Stabilizer Derivatives as Modulators of the Circadian Clock

    PubMed Central

    Lee, Jae Wook; Hirota, Tsuyoshi; Kumar, Anupriya; Kim, Nam-Jung; Irle, Stephan; Kay, Steve A

    2015-01-01

    Small-molecule probes have been playing prominent roles in furthering our understanding of the molecular underpinnings of the circadian clock. We previously discovered a carbazole derivative, KL001 (N-(3-(9H-carbazol-9-yl)-2-hydroxypropyl)-N-(furan-2-ylmethyl)methanesulfonamide), as a stabilizer of the clock protein cryptochrome (CRY). Herein we describe an extensive structure–activity relationship analysis of KL001 derivatives leading to the development of a highly active derivative: 2-(9H-carbazol-9-yl)-N-(2-chloro-6-cyanophenyl)acetamide (KL044). Subsequent 3D-QSAR analysis identified critical features of KL001 derivatives and provided a molecular-level understanding of their interaction with CRY. The electron-rich carbazole, amide/hydroxy linker, sulfonyl group, and electron-withdrawing nitrile moieties contribute to greater biological activity. The hydrogen bonding interactions with Ser394 and His357 as well as stronger CH–π interactions with Trp290 make KL044 a better binder than KL001. KL044 lengthened the circadian period, repressed Per2 activity, and stabilized CRY in reporter assays with roughly tenfold higher potency than KL001. Altogether, KL044 is a powerful chemical tool to control the function of the circadian clock through its action on CRY. PMID:26174033

  1. Development of Small-Molecule Cryptochrome Stabilizer Derivatives as Modulators of the Circadian Clock.

    PubMed

    Lee, Jae Wook; Hirota, Tsuyoshi; Kumar, Anupriya; Kim, Nam-Jung; Irle, Stephan; Kay, Steve A

    2015-09-01

    Small-molecule probes have been playing prominent roles in furthering our understanding of the molecular underpinnings of the circadian clock. We previously discovered a carbazole derivative, KL001 (N-(3-(9H-carbazol-9-yl)-2-hydroxypropyl)-N-(furan-2-ylmethyl)methanesulfonamide), as a stabilizer of the clock protein cryptochrome (CRY). Herein we describe an extensive structure-activity relationship analysis of KL001 derivatives leading to the development of a highly active derivative: 2-(9H-carbazol-9-yl)-N-(2-chloro-6-cyanophenyl)acetamide (KL044). Subsequent 3D-QSAR analysis identified critical features of KL001 derivatives and provided a molecular-level understanding of their interaction with CRY. The electron-rich carbazole, amide/hydroxy linker, sulfonyl group, and electron-withdrawing nitrile moieties contribute to greater biological activity. The hydrogen bonding interactions with Ser394 and His357 as well as stronger CH-π interactions with Trp290 make KL044 a better binder than KL001. KL044 lengthened the circadian period, repressed Per2 activity, and stabilized CRY in reporter assays with roughly tenfold higher potency than KL001. Altogether, KL044 is a powerful chemical tool to control the function of the circadian clock through its action on CRY. PMID:26174033

  2. Estimation of longitudinal stability and control derivatives for an icing research aircraft from flight data

    NASA Technical Reports Server (NTRS)

    Batterson, James G.; Omara, Thomas M.

    1989-01-01

    The results of applying a modified stepwise regression algorithm and a maximum likelihood algorithm to flight data from a twin-engine commuter-class icing research aircraft are presented. The results are in the form of body-axis stability and control derivatives related to the short-period, longitudinal motion of the aircraft. Data were analyzed for the baseline (uniced) and for the airplane with an artificial glaze ice shape attached to the leading edge of the horizontal tail. The results are discussed as to the accuracy of the derivative estimates and the difference between the derivative values found for the baseline and the iced airplane. Additional comparisons were made between the maximum likelihood results and the modified stepwise regression results with causes for any discrepancies postulated.

  3. Maximum likelihood identification and optimal input design for identifying aircraft stability and control derivatives

    NASA Technical Reports Server (NTRS)

    Stepner, D. E.; Mehra, R. K.

    1973-01-01

    A new method of extracting aircraft stability and control derivatives from flight test data is developed based on the maximum likelihood cirterion. It is shown that this new method is capable of processing data from both linear and nonlinear models, both with and without process noise and includes output error and equation error methods as special cases. The first application of this method to flight test data is reported for lateral maneuvers of the HL-10 and M2/F3 lifting bodies, including the extraction of stability and control derivatives in the presence of wind gusts. All the problems encountered in this identification study are discussed. Several different methods (including a priori weighting, parameter fixing and constrained parameter values) for dealing with identifiability and uniqueness problems are introduced and the results given. The method for the design of optimal inputs for identifying the parameters of linear dynamic systems is also given. The criterion used for the optimization is the sensitivity of the system output to the unknown parameters. Several simple examples are first given and then the results of an extensive stability and control dervative identification simulation for a C-8 aircraft are detailed.

  4. Neoproterozoic Glacial Extremes: How Plausible is the

    NASA Astrophysics Data System (ADS)

    Peltier, W. R.

    2004-05-01

    The suggestion that the glaciation events of the Neoproterozoic could have been global in extent, so-called "snowball" glaciations, during which the oceans were entirely covered by sea ice and the continents by massive continental ice sheets, is an idea tha is recurrent in the geological and climate dynamics literature. It is an idea that haa both critics and defenders but concensus concerning it's plausiblity has yet to emerge. Previous work on this problem has led to the suggestion that a more likely scenario than the "hard snowball" is one in which open water continues to persist at the equator, thus enabling biological evolution into the Cambrian to proceed, perhaps stimulated by the transition from the cold conditions of the Neoproterozoic to the warm condition of the Cambrian, thus leading to the Cambrian "explosion of life". We will discuss recent extensions of our previous efforts to model the extreme climate of the Neoproterozoic, using both the University of Toronto Glacial Systems Model and the NCAR Community Climate System Model. With an appropriate choice for the albedo of sea ice, the former model conntinues to deliver hysteresis in the surface temperature vs. CO2 concentration space when solar luminosity is reduced by 6% below modern, and thus continues to suggest the existence of the previously hypothesized "CO2 attractor". We argue here that the system could be locked onto this attractor by the strong "out of equilibrium" effects of the carbon cycle recently discussed by Rothman et al. (PNAS, 2003). The open water solution is confirmed as the preferred mode of the system by the detailed CCSM integrations that we have performed.

  5. Phase I Metabolic Stability and Electrophilic Reactivity of 2-Phenylaminophenylacetic Acid Derived Compounds.

    PubMed

    Pang, Yi Yun; Tan, Yee Min; Chan, Eric Chun Yong; Ho, Han Kiat

    2016-07-18

    Diclofenac and lumiracoxib are two highly analogous 2-phenylaminophenylacetic acid anti-inflammatory drugs exhibiting occasional dose-limiting hepatotoxicities. Prior data indicate that bioactivation and reactive metabolite formation play roles in the observed toxicity, but the exact chemical influence of the substituents remains elusive. In order to elucidate the role of chemical influence on metabolism related toxicity, metabolic stability and electrophilic reactivity were investigated for a series of structurally related analogues and their resulting metabolites. The resulting analogues embody progressive physiochemical changes through varying halogeno- and aliphatic substituents at two positions and were subjected to in vitro human liver microsomal metabolic stability and cell-based GSH depletion assays (to measure electrophilic reactivity). LC-MS/MS analysis of the GSH trapped reactive intermediates derived from the analogues was then used to identify the putative structures of reactive metabolites. We found that chemical modifications of the structural backbone led to noticeable perturbations of metabolic stability, electrophilic reactivity, and structures and composition of reactive metabolites. With the acquired data, the relationships between stability, reactivity, and toxicity were investigated in an attempt to correlate between Phase I metabolism and in vitro toxicity. A positive correlation was identified between reactivity and in vitro toxicity, indicating that electrophilic reactivity can be an indicator for in vitro toxicity. All in all, the effect of substituents on the structures and reactivity of the metabolites, however subtle the changes, should be taken into consideration during future drug design involving similar chemical features. PMID:27245204

  6. Metabolic stability of superoxide adducts derived from newly developed cyclic nitrone spin traps.

    PubMed

    Bézière, Nicolas; Hardy, Micael; Poulhès, Florent; Karoui, Hakim; Tordo, Paul; Ouari, Olivier; Frapart, Yves-Michel; Rockenbauer, Antal; Boucher, Jean-Luc; Mansuy, Daniel; Peyrot, Fabienne

    2014-02-01

    Reactive oxygen species are by-products of aerobic metabolism involved in the onset and evolution of various pathological conditions. Among them, the superoxide radical is of special interest as the origin of several damaging species such as H2O2, hydroxyl radical, or peroxynitrite (ONOO(-)). Spin trapping coupled with ESR is a method of choice to characterize these species in chemical and biological systems and the metabolic stability of the spin adducts derived from reaction of superoxide and hydroxyl radicals with nitrones is the main limit to the in vivo application of the method. Recently, new cyclic nitrones bearing a triphenylphosphonium or permethylated β-cyclodextrin moiety have been synthesized and their spin adducts demonstrated increased stability in buffer. In this article, we studied the stability of the superoxide adducts of four new cyclic nitrones in the presence of liver subcellular fractions and biologically relevant reductants using an original setup combining a stopped-flow device and an ESR spectrometer. The kinetics of disappearance of the spin adducts were analyzed using an appropriate simulation program. Our results highlight the interest of the new spin trapping agents CD-DEPMPO and CD-DIPPMPO for specific detection of superoxide with high stability of the superoxide adducts in the presence of liver microsomes. PMID:24161442

  7. Development and Validation of Stability-Indicating Derivative Spectrophotometric Methods for Determination of Dronedarone Hydrochloride

    NASA Astrophysics Data System (ADS)

    Chadha, R.; Bali, A.

    2016-05-01

    Rapid, sensitive, cost effective and reproducible stability-indicating derivative spectrophotometric methods have been developed for the estimation of dronedarone HCl employing peak-zero (P-0) and peak-peak (P-P) techniques, and their stability-indicating potential assessed in forced degraded solutions of the drug. The methods were validated with respect to linearity, accuracy, precision and robustness. Excellent linearity was observed in concentrations 2-40 μg/ml (r 2 = 0.9986). LOD and LOQ values for the proposed methods ranged from 0.42-0.46 μg/ml and 1.21-1.27 μg/ml, respectively, and excellent recovery of the drug was obtained in the tablet samples (99.70 ± 0.84%).

  8. Development and Validation of Stability-Indicating Derivative Spectrophotometric Methods for Determination of Dronedarone Hydrochloride

    NASA Astrophysics Data System (ADS)

    Chadha, R.; Bali, A.

    2016-05-01

    Rapid, sensitive, cost effective and reproducible stability-indicating derivative spectrophotometric methods have been developed for the estimation of dronedarone HCl employing peak-zero (P-0) and peak-peak (P-P) techniques, and their stability-indicating potential assessed in forced degraded solutions of the drug. The methods were validated with respect to linearity, accuracy, precision and robustness. Excellent linearity was observed in concentrations 2-40 μg/ml ( r 2 = 0.9986). LOD and LOQ values for the proposed methods ranged from 0.42-0.46 μg/ml and 1.21-1.27 μg/ml, respectively, and excellent recovery of the drug was obtained in the tablet samples (99.70 ± 0.84%).

  9. Nanocomplexation of thrombin with cationic amylose derivative for improved stability and hemostatic efficacy.

    PubMed

    Zhuang, Baoxiong; Li, Zhihua; Pang, Jiadong; Li, Wenbin; Huang, Pinbo; Wang, Jie; Zhou, Yu; Lin, Qing; Zhou, Quanbo; Ye, Xiao; Ye, Huilin; Liu, Yimin; Zhang, Li-Ming; Chen, Rufu

    2015-01-01

    As a topical hemostatic agent, thrombin has wide application for many surgical treatments. However, native thrombin always suffers from its physical and chemical instabilities. In this work, a nanocomplexation strategy was developed for modifying the stability and hemostatic efficacy of thrombin, in which a water-soluble cationic amylose derivative containing poly(l-lysine) dendrons was prepared by a click reaction and then used to complex thrombin in an aqueous system. For resultant thrombin nanocomplexes, their morphology and particle size distribution were investigated. Their stabilities were studied in terms of activity retention percentages under different storage time, pH values, and illumination time. In addition, their ability to achieve in vitro fibrinogen and blood coagulation were evaluated. Via a rat hepatic hemorrhage model and a rat iliac artery hemorrhage model, these thrombin nanocomplexes were confirmed to have good tissue biocompatibility and in vivo hemostatic effectiveness. PMID:25673989

  10. Nanocomplexation of thrombin with cationic amylose derivative for improved stability and hemostatic efficacy

    PubMed Central

    Zhuang, Baoxiong; Li, Zhihua; Pang, Jiadong; Li, Wenbin; Huang, Pinbo; Wang, Jie; Zhou, Yu; Lin, Qing; Zhou, Quanbo; Ye, Xiao; Ye, Huilin; Liu, Yimin; Zhang, Li-Ming; Chen, Rufu

    2015-01-01

    As a topical hemostatic agent, thrombin has wide application for many surgical treatments. However, native thrombin always suffers from its physical and chemical instabilities. In this work, a nanocomplexation strategy was developed for modifying the stability and hemostatic efficacy of thrombin, in which a water-soluble cationic amylose derivative containing poly(l-lysine) dendrons was prepared by a click reaction and then used to complex thrombin in an aqueous system. For resultant thrombin nanocomplexes, their morphology and particle size distribution were investigated. Their stabilities were studied in terms of activity retention percentages under different storage time, pH values, and illumination time. In addition, their ability to achieve in vitro fibrinogen and blood coagulation were evaluated. Via a rat hepatic hemorrhage model and a rat iliac artery hemorrhage model, these thrombin nanocomplexes were confirmed to have good tissue biocompatibility and in vivo hemostatic effectiveness. PMID:25673989

  11. A FORTRAN program for determining aircraft stability and control derivatives from flight data

    NASA Technical Reports Server (NTRS)

    Maine, R. E.; Iliff, K. W.

    1975-01-01

    A digital computer program written in FORTRAN IV for the estimation of aircraft stability and control derivatives is presented. The program uses a maximum likelihood estimation method, and two associated programs for routine, related data handling are also included. The three programs form a package that can be used by relatively inexperienced personnel to process large amounts of data with a minimum of manpower. This package was used to successfully analyze 1500 maneuvers on 20 aircraft, and is designed to be used without modification on as many types of computers as feasible. Program listings and sample check cases are included.

  12. Fractional derivation stabilizing virtue-induced quenching phenomena in coupled oscillators

    NASA Astrophysics Data System (ADS)

    Ngueuteu, G. S. M.; Yamapi, R.; Woafo, P.

    2015-11-01

    We investigate quenching oscillations phenomena in a system of two diffusively and mutually coupled identical fractional-order Stuart-Landau oscillators. We first consider the uncoupled unit and find that the stabilizing virtue of the fractional derivative yields suppression of oscillations via a Hopf bifurcation. The oscillatory solutions of the fractional-order Stuart-Landau equation are provided as well. Quenching phenomena are then investigated in the coupled system. It is found that the fractional derivatives enhance oscillation death by widening its domain of existence in coupling strength space and initial conditions space, leading to oscillation death dominance. A region of stable homogeneous steady state appears where the uncoupled oscillators are resting and not oscillating as usually accepted for the realization of amplitude death.

  13. Wettability Control of Gold Surfaces Modified with Benzenethiol Derivatives: Water Contact Angle and Thermal Stability.

    PubMed

    Tatara, Shingo; Kuzumoto, Yasutaka; Kitamura, Masatoshi

    2016-04-01

    The water wettability of Au surfaces has been controlled using various benzenethiol derivatives including 4-methylbenzenethiol, pentafluorobenzenethiol, 4-flubrobenzenethiol, 4-methoxy-benzenethiol, 4-nitrobenzenethiol, and 4-hydroxybenzenethiol. The water contact angle of the Au surface modified with the benzenethiol derivative was found to vary in the wide range of 30.9° to 88.3°. The contact angle of the modified Au films annealed was also measured in order to investigate their thermal stability. The change in the contact angle indicated that the modified surface is stable at temperatures below about 400 K. Meanwhile, the activation energy of desorption from the modified surface was estimated from the change in the contact angle. The modified Au surface was also examined using X-ray photoelectron spectroscopy. PMID:27451620

  14. Observability and confidence of stability and control derivatives determined in real time

    NASA Astrophysics Data System (ADS)

    Noriega, Alfonso

    Stability and control derivatives of an aircraft were estimated from real flight test data in real time. A higher language block diagram library was developed for this purpose. Parameter identification techniques and requirements were used to detect and rate maneuvers present in the data. These ratings were used to blend newly calculated derivatives with previously known values by means of a Kalman filter. The Kalman filter output was used to identify the health of control surfaces actuators. Statistical and measured data were used to predict the probability that an actuator failure has occurred at any given time during the flight. Sweeps of all the tuning parameters of the system were performed, and it was demonstrated that these tuning parameters can be used to obtain the desired performance based on requirements.

  15. New benzimidazole derivatives with potential cytotoxic activity--study of their stability by RP-HPLC.

    PubMed

    Błaszczak-Świątkiewicz, Katarzyna; Mirowski, Marek; Kaplińska, Katarzyna; Kruszyński, Rafał; Trzęsowska-Kruszyńska, Agata; Mikiciuk-Olasik, Elżbieta

    2012-01-01

    Obtained benzimidazole derivatives, our next synthesized heterocyclic compounds, belong to a new group of chemical bondings with potential anticancer properties (Błaszczak-Świątkiewicz & Mikiciuk-Olasik, 2006, J Liguid Chrom Rel Tech 29: 2367-2385; Błaszczak-Świątkiewicz & Mikiciuk-Olasik, 2008, Wiad Chem 62: 11-12, in Polish; Błaszczak-Świątkiewicz & Mikiciuk-Olasik, 2011, J Liguid Chrom Rel Tech 34: 1901-1912). We used HPLC analysis to determine stability of these compounds in 0.2% DMSO (dimethyl sulfoxide). Optimisation of the chromatographic system and validation of the established analytical method were performed. Reversed phases (RP-18) and a 1:1 mixture of acetate buffer (pH 4.5) and acetonitrile as a mobile phase were used for all the analysed compounds at a flow rate 1.0 mL/min. The eluted compounds were monitored using a UV detector, the wavelength was specific for compounds 6 and 9 and compounds 7 and 10. The retention time was specific for all four compounds. The used method was found to have linearity in the concentration range of (0.1 mg/mL-0.1 μg/mL) with a correlation coefficient not less than r(2)=0.9995. Statistical validation of the method proved it to be a simple, highly precise and accurate way to determine the stability of benzimidazole derivatives in 0.2% DMSO. The recoveries of all four compounds examined were in the range 99.24-100.00%. The developed HPLC analysis revealed that the compounds studied remain homogeneous in 0.2% DMSO for up to 96 h and that the analysed N-oxide benzimidazole derivatives do not disintegrate into their analogues - benzimidazole derivatives. Compounds 8, 6 and 9 exhibit the best cytotoxic properties under normoxic conditions when tested against cells of human malignant melanoma WM 115. PMID:22693687

  16. A new steroid derivative stabilizes g-quadruplexes and induces telomere uncapping in human tumor cells.

    PubMed

    Brassart, Bertrand; Gomez, Dennis; De Cian, Anne; Paterski, Rajaa; Montagnac, Alain; Qui, Khuong-Huu; Temime-Smaali, Nassima; Trentesaux, Chantal; Mergny, Jean-Louis; Gueritte, Françoise; Riou, Jean-François

    2007-09-01

    Human telomeric DNA consists of tandem repeats of the sequence d(TTAGGG) with a 3' single-stranded extension (the G-overhang). The stabilization of G-quadruplexes in the human telomeric sequence by small-molecule ligands inhibits the activity of telomerase and results in telomere uncapping, leading to senescence or apoptosis of tumor cells. Therefore, the search for new and selective G-quadruplex ligands is of considerable interest because a selective ligand might provide a telomere-targeted therapeutic approach to treatment of cancer. We have screened a bank of derivatives from natural and synthetic origin using a temperature fluorescence assay and have identified two related compounds that induce G-quadruplex stabilization: malouetine and steroid FG. These steroid derivatives have nonplanar and nonaromatic structures, different from currently known G-quadruplex ligands. Malouetine is a natural product isolated from the leaves of Malouetia bequaaertiana E. Woodson and is known for its curarizing and DNA-binding properties. Steroid FG, a funtumine derivative substituted with a guanylhydrazone moiety, interacted selectively with the telomeric G-quadruplex in vitro. This derivative induced senescence and telomere shortening of HT1080 tumor cells at submicromolar concentrations, corresponding to the phenotypic inactivation of telomerase activity. In addition, steroid FG induced a rapid degradation of the telomeric G-overhang and the formation of anaphase bridges, characteristics of telomere uncapping. Finally, the expression of protection of telomere 1 (POT1) induced resistance to the growth effect of steroid FG. These results indicate that these steroid ligands represent a new class of telomere-targeted agents with potential as antitumor drugs. PMID:17586599

  17. Structure, Stability, and Thermochemistry of the Fullerene Derivatives C64X6 (X = H, F, Cl)

    NASA Astrophysics Data System (ADS)

    Xu, Lei; Shao, Xueguang; Cai, Wensheng

    2009-09-01

    The geometrical structures, electronic properties, and stabilities of the unconventional fullerene derivatives C64X6 (X = H, F, Cl) have been systematically studied by the first-principle calculations based on the density functional theory. The fullerene derivatives 1911(2)-C64X6 generated from the pineapple-shaped C64X4 are predicted to possess the lowest energies. The other two X atoms are added to the carbon atoms with the highest local strain assessed by the pyramidalization angles. The calculations of the nucleus-independent chemical shifts suggest that the aromaticity of C64X6 affects the stability order of the derivative isomers. To address why C64H6 was not observed in the experimental study of Wang et al. (J. Am. Chem. Soc. 2006, 128, 6605) and if the halogenated derivatives C64X6 (X = F, Cl) can be synthesized, thermochemical analysis of the reaction C64X4 + X2 → C64X6 was also performed. The results indicate that the formation of C64H6 and C64Cl6 is not favored at high temperatures. The former may be a reason why C64H6 was not found in the experiment. In sharp contrast, the Gibbs free energy change to form C64F6 is found to be -23.29 kcal/mol at 2000 K, suggesting that this compound may be formed and detected in experiments. The NMR and IR spectra of 1911(2)-C64F6 are sequentially calculated and presented to facilitate future experimental identification.

  18. Examining the Stability of "DSM-IV" and Empirically Derived Eating Disorder Classification: Implications for "DSM-5"

    ERIC Educational Resources Information Center

    Peterson, Carol B.; Crow, Scott J.; Swanson, Sonja A.; Crosby, Ross D.; Wonderlich, Stephen A.; Mitchell, James E.; Agras, W. Stewart; Halmi, Katherine A.

    2011-01-01

    Objective: The purpose of this investigation was to derive an empirical classification of eating disorder symptoms in a heterogeneous eating disorder sample using latent class analysis (LCA) and to examine the longitudinal stability of these latent classes (LCs) and the stability of DSM-IV eating disorder (ED) diagnoses. Method: A total of 429…

  19. An Insight into Different Stabilization Mechanisms of Phenytoin Derivatives Supersaturation by HPMC and PVP.

    PubMed

    Otsuka, Naoya; Ueda, Keisuke; Ohyagi, Naoko; Shimizu, Kozue; Katakawa, Kazuaki; Kumamoto, Takuya; Higashi, Kenjirou; Yamamoto, Keiji; Moribe, Kunikazu

    2015-08-01

    In this study, we examined the stabilization mechanism of drug supersaturation by hypromellose (HPMC) and polyvinylpirrolidone (PVP). The poorly water-soluble drugs, phenytoin (diphenylhydantoin, DPH), and its synthesized derivatives monomethylphenytoin (MDPH) and dimethylphenytoin (DMDPH) were used. DPH supersaturation was efficiently maintained by both HPMC and PVP. HPMC maintained the supersaturation of MDPH and DMDPH in a similar manner to that of DPH, whereas the ability of PVP to maintain drug supersaturation increased as follows: DPH > MDPH > DMDPH. Caco-2 permeation studies and nuclear magnetic resonance measurements revealed that the permeability and molecular state of the drug in a HPMC solution barely changed. In fact, the solubilization of the drug into PVP changed its apparent permeability and molecular state. The drug solubilization efficiency by PVP was higher and followed the order: DPH > MDPH > DMDPH. The different drug solubilization efficiencies most likely result from the different strengths in the intermolecular interaction between the DPH derivatives and PVP. The difference in the stabilization mechanism of drug supersaturation by HPMC and PVP could determine whether the efficient maintenance of the drug supersaturation was dependent on the drug species. PMID:26059285

  20. A computational study on the enhanced stabilization of aminophenol derivatives by internal hydrogen bonding

    NASA Astrophysics Data System (ADS)

    Gomes, José R. B.; Ribeiro da Silva, Manuel A. V.

    2006-05-01

    The stabilization of aminophenol derivatives and their radicals due to internal hydrogen bonding has been analyzed by means of density functional theory and by topological electron density analysis. The calculations have been carried out at the B3LYP level of theory, using several basis sets, and by means of the CBS-4M composite approach. A strong O-H⋯NH 2 hydrogen bond is found to stabilize the aminophenol with the lone-pair of the nitrogen atom co-planar with the aromatic ring, contrasting with the optimized structure found for aniline. The effect of electron donors and electron acceptors on the strength of the internal hydrogen bond is also analyzed. For one of the species studied, 2,6-diaminophenol, the computed O-H bond dissociation enthalpy is only 300 kJ/mol, the lowest value found so far for phenol and other compounds containing the O-H bond, almost 25 kJ/mol lower than those found experimentally for pyrogallol and for vitamin E. The explanation for such a small value comes from the enhanced stabilization of the corresponding radical species by internal hydrogen bonding, combined with a decrease of the steric effects caused by rotation of the amino groups.

  1. Chemical synthesis and formulation design of a PEGylated vasoactive intestinal peptide derivative with improved metabolic stability.

    PubMed

    Onoue, Satomi; Matsui, Takuya; Kato, Masashi; Mizumoto, Takahiro; Liu, Baosheng; Liu, Liang; Karaki, Shin-ichiro; Kuwahara, Atsukazu; Yamada, Shizuo

    2013-06-14

    The present study aimed to design a PEGylated VIP derivative, [Arg(15, 20, 21), Leu(17)]-VIP-GRR (IK312532), with improved metabolic stability, and develop its respirable powder (RP) formulation for inhalation therapy. IK312532 was chemically conjugated with PEG (5 kDa, P5K), the physicochemical and biochemical properties of which were characterized by CD spectral analysis, binding assays, and metabolic stability. CD spectral analysis demonstrated that PEG conjugation had no impact on the conformational structure of IK312532. Although the receptor-binding activity of IK312532/P5K (IC₅₀: 82 nM) was estimated to be ca. 30-fold less than that of IK312532 (IC₅₀: 2.8 nM), the metabolic stability of IK312532/P5K was highly improved. The IK312532/P5K was jet-milled and blended with lactose carrier particles to provide RP formulation of IK312532/P5K (IK312532/P5K-RP). In vitro inhalation performance and in vivo pharmacological effects of the IK312532/P5K-RP in antigen-sensitized rats were also evaluated. In cascade impactor analyses, fine particle fraction of IK312532/P5K-RP was calculated to be ca. 37%. Insufflation of IK312532/P5K-RP (150 μg of IK312532/P5K) in antigen-sensitized rats resulted in marked attenuation of inflammatory events, as evidenced by significant decreases in inflammatory biomarkers and granulocyte recruitment in pulmonary tissue 24h after the antigen challenge. From these findings, PEGylation of a VIP derivative, as well as its strategic application to the RP formulation, may be a viable approach to improve its therapeutic potential for the treatment of airway inflammatory diseases. PMID:23608612

  2. Source Effects and Plausibility Judgments When Reading about Climate Change

    ERIC Educational Resources Information Center

    Lombardi, Doug; Seyranian, Viviane; Sinatra, Gale M.

    2014-01-01

    Gaps between what scientists and laypeople find plausible may act as a barrier to learning complex and/or controversial socioscientific concepts. For example, individuals may consider scientific explanations that human activities are causing current climate change as implausible. This plausibility judgment may be due-in part-to individuals'…

  3. Plausibility Judgments in Conceptual Change and Epistemic Cognition

    ERIC Educational Resources Information Center

    Lombardi, Doug; Nussbaum, E. Michael; Sinatra, Gale M.

    2016-01-01

    Plausibility judgments rarely have been addressed empirically in conceptual change research. Recent research, however, suggests that these judgments may be pivotal to conceptual change about certain topics where a gap exists between what scientists and laypersons find plausible. Based on a philosophical and empirical foundation, this article…

  4. Enzyme stabilization by glass-derived silicates in glass-exposed aqueous solutions

    USGS Publications Warehouse

    Ives, J.A.; Moffett, J.R.; Arun, P.; Lam, D.; Todorov, T.I.; Brothers, A.B.; Anick, D.J.; Centeno, J.; Namboodiri, M.A.A.; Jonas, W.B.

    2010-01-01

    Objectives: To analyze the solutes leaching from glass containers into aqueous solutions, and to show that these solutes have enzyme activity stabilizing effects in very dilute solutions. Methods: Enzyme assays with acetylcholine esterase were used to analyze serially succussed and diluted (SSD) solutions prepared in glass and plastic containers. Aqueous SSD preparations starting with various solutes, or water alone, were prepared under several conditions, and tested for their solute content and their ability to affect enzyme stability in dilute solution. Results: We confirm that water acts to dissolve constituents from glass vials, and show that the solutes derived from the glass have effects on enzymes in the resultant solutions. Enzyme assays demonstrated that enzyme stability in purified and deionized water was enhanced in SSD solutions that were prepared in glass containers, but not those prepared in plastic. The increased enzyme stability could be mimicked in a dose-dependent manner by the addition of silicates to the purified, deionized water that enzymes were dissolved in. Elemental analyses of SSD water preparations made in glass vials showed that boron, silicon, and sodium were present at micromolar concentrations. Conclusions: These results show that silicates and other solutes are present at micromolar levels in all glass-exposed solutions, whether pharmaceutical or homeopathic in nature. Even though silicates are known to have biological activity at higher concentrations, the silicate concentrations we measured in homeopathic preparations were too low to account for any purported in vivo efficacy, but could potentially influence in vitro biological assays reporting homeopathic effects. ?? 2009 The Faculty of Homeopathy.

  5. A probabilistic model of semantic plausibility in sentence processing.

    PubMed

    Padó, Ulrike; Crocker, Matthew W; Keller, Frank

    2009-07-01

    Experimental research shows that human sentence processing uses information from different levels of linguistic analysis, for example, lexical and syntactic preferences as well as semantic plausibility. Existing computational models of human sentence processing, however, have focused primarily on lexico-syntactic factors. Those models that do account for semantic plausibility effects lack a general model of human plausibility intuitions at the sentence level. Within a probabilistic framework, we propose a wide-coverage model that both assigns thematic roles to verb-argument pairs and determines a preferred interpretation by evaluating the plausibility of the resulting (verb, role, argument) triples. The model is trained on a corpus of role-annotated language data. We also present a transparent integration of the semantic model with an incremental probabilistic parser. We demonstrate that both the semantic plausibility model and the combined syntax/semantics model predict judgment and reading time data from the experimental literature. PMID:21585487

  6. Stability and cytotoxicity of angiotensin-I-converting enzyme inhibitory peptides derived from bovine casein*

    PubMed Central

    Wu, Wei; Yu, Pan-pan; Zhang, Feng-yang; Che, Hong-xia; Jiang, Zhan-mei

    2014-01-01

    This study investigated the effect of heat treatment combined with acid and alkali on the angiotensin-I-converting enzyme (ACE) inhibitory activity of peptides derived from bovine casein. The free amino group content, color, and cytotoxicity of the peptides were measured under different conditions. When heated at 100 °C in the pH range from 9.0 to 12.0, ACE inhibitory activity was reduced and the appearance of the peptides was significantly darkened. After thermal treatment in the presence of acid and alkali, the free amino group content of ACE inhibitory peptides decreased markedly. High temperature and prolonged heating also resulted in the loss of ACE inhibitory activity, the loss of free amino groups, and the darker coloration of bovine casein-derived peptides. However, ACE inhibitory peptides, within a concentration range of from 0.01 to 0.2 mg/ml, showed no cytotoxicity to Caco-2 and ECV-304 cell lines after heat treatment. This indicated that high temperature and alkaline heat treatment impaired the stability of bovine casein-derived ACE inhibitory peptides. PMID:24510707

  7. Effect of Self-Association on the Phase Stability of Triphenylamine Derivatives.

    PubMed

    Lima, Carlos F R A C; Costa, José C S; Melo, André; Tavares, Hilário R; Silva, Artur M S; Santos, Luís M N B F

    2015-06-25

    The self-association equilibrium, i.e. formation of noncovalent dimers, in two triphenylamine derivatives, TPD (N,N'-bis(3-methylphenyl)-N,N'-diphenylbenzidine) and mMTDAB (1,3,5-tris[(3-methylphenyl)phenylamino]benzene), in solution was evaluated by (1)H NMR spectroscopy. The gas-phase energetics of the respective dimerization processes was explored by computational quantum chemistry. The results indicate that self-association is significantly more extensive in TPB than in TDAB. It is proposed that this fact helps to explain why TPB presents a stability higher than expected in the liquid phase, which is reflected in a lower melting temperature, a less volatile liquid, and possibly a higher tendency to form a glass. These results highlight the influence of self-association on the phase equilibria and thermodynamic properties of pure organic substances. PMID:26035212

  8. Stability, transdermal penetration, and cutaneous effects of ascorbic acid and its derivatives.

    PubMed

    Stamford, Nicholas P J

    2012-12-01

    Topically applied antioxidants exert their benefits by offering protection from damaging free radicals and over-the-counter cosmeceuticals incorporating antioxidants are among the most popular anti-aging products available. One potent antioxidant of particular note, vitamin C, has been extensively utilized because it possesses a variety of other cutaneous benefits including photoprotection from UV A & B, neocollagenesis, inhibition of melanogenesis and improvement of a variety of inflammatory skin disorders. However, the instability of this water-soluble vitamin, together with difficulties associated with its topical delivery, has presented issues for the formulation chemist. This article reviews the scientific data and clinical studies that underpin the stability, percutaneous absorption, and cutaneous effects of vitamin C together with its commonly utilized, commercially available derivatives. PMID:23174055

  9. Thermal stability of some aircraft turbine fuels derived from oil shale and coal

    NASA Technical Reports Server (NTRS)

    Reynolds, T. W.

    1977-01-01

    Thermal stability breakpoint temperatures are shown for 32 jet fuels prepared from oil shale and coal syncrudes by various degrees of hydrogenation. Low severity hydrotreated shale oils, with nitrogen contents of 0.1 to 0.24 weight percent, had breakpoint temperatures in the 477 to 505 K (400 to 450 F) range. Higher severity treatment, lowering nitrogen levels to 0.008 to 0.017 weight percent, resulted in breakpoint temperatures in the 505 to 533 K (450 to 500 F) range. Coal derived fuels showed generally increasing breakpoint temperatures with increasing weight percent hydrogen, fuels below 13 weight percent hydrogen having breakpoints below 533 K (500 F). Comparisons are shown with similar literature data.

  10. Synthesis, Tribological and Hydrolysis Stability Study of Novel Benzotriazole Borate Derivative

    PubMed Central

    Liping, Xiong; Zhongyi, He; Liang, Qian; Lin, Mu; Aixi, Chen; Sheng, Han; Jianwei, Qiu; Xisheng, Fu

    2014-01-01

    Benzotriazole and borate derivatives have long been used as multifunctional additives to lubricants. A novel, environmentally friendly additive borate ester (NHB), which contains boron, ethanolamine, and benzotriazole groups in one molecule, was synthesized by a multi-step reaction, and its tribological properties in rapeseed oil (RSO) were investigated by a four-ball tribometer. The hydrolysis stability of the additive was investigated by half-time and open observation methods, and the mechanism of hydrolysis stability was discussed through Gaussian calculation. The novel compound NHB showed excellent performance under extreme pressure, against wearing, and in reducing friction, and its hydrolysis time is more than 1,220 times, which is better than that of triethyl borate. The mass ratio of NHB is bigger than that of the mixed liquid of triethyl borate and ethanolamine. The lone electron of amino N atoms forms a coordination effect with the B atom to compensate for the shortage of electrons in the B atom and to improve the hydrolysis stability of NHB. The surface morphology and the traces of different elements in the tribofilms formed with 1.0 wt.% NHB in were detected with scanning electron microscopy(SEM), energy dispersive X-ray spectroscopy (EDX)and X-ray photoelectron spectroscopy(XPS). The results shown that the additive caused a tribochemical reaction with the steel ball surface during the lubricating process. A mixed boundary lubrication film that contains organic nitrogen and inorganic salts, such as BN, B2O3, FeOx, Fe–O–B, and FeB, was also formed, and the formation of the lubricating film improved the tribological properties of the base oil. PMID:24465382

  11. Genetic stability of bone marrow-derived human mesenchymal stromal cells in the Quantum System

    PubMed Central

    Jones, Mark; Varella-Garcia, Marileila; Skokan, Margaret; Bryce, Steven; Schowinsky, Jeffrey; Peters, Rebecca; Vang, Boah; Brecheisen, Michelle; Startz, Thomas; Frank, Nathan; Nankervis, Brian

    2014-01-01

    Background aims The Quantum® Cell Expansion System (Quantum; Terumo BCT, Inc, Lakewood, CO, USA) is a novel hollow fiber-based device that automates and closes the cell culture process, reducing labor intensive tasks such as manual cell culture feeding and harvesting. The manual cell selection and expansion processes for the production of clinical-scale quantities of bone marrow-derived human mesenchymal stromal cells (BM-hMSCs) have been successfully translated onto the Quantum platform previously. The formerly static, manual, in vitro process performed primarily on tissue culture polystyrene substrates may raise the question of whether BM-hMSCs cultured on a hollow fiber platform yields comparable cell quality. Methods A rigorous battery of assays was used to determine the genetic stability of BM-hMSCs selected and produced with the Quantum. In this study, genetic stability was determined by assessing spectral karyotype, micronucleus formation and tumorigenicity to resolve chromosomal aberrations in the stem cell population. Cell phenotype, adherent growth kinetics and tri-lineage differentiation were also evaluated. HMSC bone marrow aspirates, obtained from three approved donors, were expanded in parallel using T225 culture flasks and the Quantum. Results BM-hMSCs harvested from the Quantum demonstrated immunophenotype, morphology and tri-lineage differentiation capacity characteristics consistent with the International Society of Cell Therapy standard for hMSCs. Cell populations showed no malignant neoplastic formation in athymic mice 60 days post-transplant, no clonal chromosomal aberrations were observed and no DNA damage was found as measured by micronucleus formation. Conclusions Quantum-produced BM-hMSCs are of comparable quality and demonstrate analogous genetic stability to BM-hMSCs cultured on tissue culture polystyrene substrates. PMID:23992670

  12. Dihydrochelerythrine and its derivatives: Synthesis and their application as potential G-quadruplex DNA stabilizing agents.

    PubMed

    Malhotra, Rajesh; Rarhi, Chhanda; Diveshkumar, K V; Barik, Rajib; D'cunha, Ruhee; Dhar, Pranab; Kundu, Mrinalkanti; Chattopadhyay, Subrata; Roy, Subho; Basu, Sourav; Pradeepkumar, P I; Hajra, Saumen

    2016-07-01

    A convenient route was envisaged toward the synthesis of dihydrochelerythrine (DHCHL), 4 by intramolecular Suzuki coupling of 2-bromo-N-(2-bromobenzyl)-naphthalen-1-amine derivative 5 via in situ generated arylborane. This compound was converted to (±)-6-acetonyldihydrochelerythrine (ADC), 3 which was then resolved by chiral prep-HPLC. Efficiency of DHCHL for the stabilization of promoter quadruplex DNA structures and a comparison study with the parent natural alkaloid chelerythrine (CHL), 1 was performed. A thorough investigation was carried out to assess the quadruplex binding affinity by using various biophysical and biochemical studies and the binding mode was explained by using molecular modeling and dynamics studies. Results clearly indicate that DHCHL is a strong G-quadruplex stabilizer with affinity similar to that of the parent alkaloid CHL. Compounds ADC and DHCHL were also screened against different human cancer cell lines. Among the cancer cells, (±)-ADC and its enantiomers showed varied (15-48%) inhibition against human colorectal cell line HCT116 and breast cancer cell line MDA-MB-231 albeit low enantio-specificity in the inhibitory effect; whereas DHCHL showed 30% inhibition against A431 cell line only, suggesting the compounds are indeed cancer tissue specific. PMID:27234888

  13. Real-Time Stability and Control Derivative Extraction From F-15 Flight Data

    NASA Technical Reports Server (NTRS)

    Smith, Mark S.; Moes, Timothy R.; Morelli, Eugene A.

    2003-01-01

    A real-time, frequency-domain, equation-error parameter identification (PID) technique was used to estimate stability and control derivatives from flight data. This technique is being studied to support adaptive control system concepts currently being developed by NASA (National Aeronautics and Space Administration), academia, and industry. This report describes the basic real-time algorithm used for this study and implementation issues for onboard usage as part of an indirect-adaptive control system. A confidence measures system for automated evaluation of PID results is discussed. Results calculated using flight data from a modified F-15 aircraft are presented. Test maneuvers included pilot input doublets and automated inputs at several flight conditions. Estimated derivatives are compared to aerodynamic model predictions. Data indicate that the real-time PID used for this study performs well enough to be used for onboard parameter estimation. For suitable test inputs, the parameter estimates converged rapidly to sufficient levels of accuracy. The devised confidence measures used were moderately successful.

  14. Estrogenic and antiandrogenic activities of 17 benzophenone derivatives used as UV stabilizers and sunscreens

    SciTech Connect

    Suzuki, Tomoharu; Kitamura, Shigeyuki . E-mail: skitamu@hiroshima-u.ac.jp; Khota, Ryuki; Sugihara, Kazumi; Fujimoto, Nariaki; Ohta, Shigeru

    2005-02-15

    Estrogenic and antiandrogenic activities of benzophenone and 16 of its derivatives, which are used as UV stabilizers, were comparatively examined with hormone-responsive reporter assay in various cell lines. Hydroxylated benzophenones exhibited estrogenic activity in human breast cancer cell line MCF-7, but their activities varied markedly. The highest activity was observed with 2,4,4'-trihydroxybenzophenone (2.4.4'-triOH-BP), followed by 2,3',4,4'-tetrahydroxybenzophenone, 4,4'-dihydroxybenzophenone, 2,2',4,4'-tetrahydroxybenzophenone, 4-hydroxybenzophenone and 2,4-dihydroxybenzophenone. Benzophenone itself showed little activity in the assay. In contrast, benzophenone and some related compounds showed significant inhibitory effects on the androgenic activity of dihydrotestosterone in rat fibroblast cell line NIH3T3. The highest activity was observed with 2,4,4'-triOH-BP, followed by 2,3',4,4'-tetrahydroxybenzophenone, 2,2',4,4'-tetrahydroxybenzophenone, 3-hydroxybenzophenone and 2,2'-dihydroxybenzophenone. However, 2,3,4,4'-tetrahydroxybenzophenone and 2,3,4-trihydroxybenzophenone showed little activity. 2,4-Dihydroxybenzophenone, 2,4,4'-triOH-BP and benzophenone gave positive responses in uterotrophic assay using ovariectomized rats, and 2,4,4'-triOH-BP was positive in the Hershberger assay using castrated rats. These results suggest that a 4-hydroxyl group on the phenyl ring of benzophenone derivatives is essential for high hormonal activities, and the presence of other hydroxyl groups markedly alters these activities.

  15. Explicit determination of lateral-directional stability and control derivatives by simutaneous time vector analysis of two maneuvers

    NASA Technical Reports Server (NTRS)

    Gilyard, G. B.

    1973-01-01

    An extension of the time vector technique for determining stability and control derivatives from flight data is formulated. The technique provides for explicit determination of derivatives by means of simultaneous analysis of two maneuvers which differ by a dependent control input. The control derivatives for the dependent input are also explicitly determined. This extended technique is preferable to the application of the time vector method to single maneuvers in that no estimates of derivatives are required. An example illustrating the application of the technique is given.

  16. Application of plausible reasoning to AI-based control systems

    NASA Technical Reports Server (NTRS)

    Berenji, Hamid; Lum, Henry, Jr.

    1987-01-01

    Some current approaches to plausible reasoning in artificial intelligence are reviewed and discussed. Some of the most significant recent advances in plausible and approximate reasoning are examined. A synergism among the techniques of uncertainty management is advocated, and brief discussions on the certainty factor approach, probabilistic approach, Dempster-Shafer theory of evidence, possibility theory, linguistic variables, and fuzzy control are presented. Some extensions to these methods are described, and the applications of the methods are considered.

  17. Investigation at Low Speeds of the Effect of Aspect Ratio and Sweep on Rolling Stability Derivatives of Untapered Wings

    NASA Technical Reports Server (NTRS)

    Goodman, Alex; Fisher, Lewis R

    1950-01-01

    A low-scale wind-tunnel investigation was conducted in rolling flow to determine the effects of aspect ratio and sweep (when varied independently) on the rolling stability derivatives for a series of untapered wings. The rolling-flow equipment of the Langley stability tunnel was used for the tests. The data of the investigation have been used to develop a method of accounting for the effects of the drag on the yawing moment due to rolling throughout the lift range.

  18. Wind-tunnel Measurement of Propeller Whirl-flutter Speeds and Static-stability Derivatives and Comparison with Theory

    NASA Technical Reports Server (NTRS)

    Bland, Samuel R.; Bennett, Robert M.

    1963-01-01

    Results of an experimental investigation of propeller whirl flutter are presented for a model consisting of an isolated, rigid system of propeller and simulated power plant mounted with flexibility in pitch and yaw on a rigid sting. A range of propeller blade angles, restraint stiffnesses, and restraint damping coefficients was investigated for a system symmetrical i n pitch and yaw with a windmilling propeller. Measurements of the static-stability derivatives were also made by using a simple balance and were compared with two sets of theoretical derivatives. Whirl-flutter calculations were made with the theoretical and measured derivatives. Some limited results were obtained for the whirl flutter of the model mounted on a cantilever semispan wing. The measured whirl-flutter speeds and frequencies of the isolated model were in very good agreement with those predicted by calculations in which measured derivatives and viscous damping were used. This agreement was better than that obtained by using structural damping. Predicted whirl-flutter speeds for the isolated model were lower when theoretical stability derivatives were used than when measured derivatives were used. The theoretical and experimental static-stability derivatives exhibited the same trends, but in certain instances differed appreciably in magnitude. the measured whirl-flutter boundary for the one configuration considered.

  19. Pilgrims sailing the Titanic: plausibility effects on memory for misinformation.

    PubMed

    Hinze, Scott R; Slaten, Daniel G; Horton, William S; Jenkins, Ryan; Rapp, David N

    2014-02-01

    People rely on information they read even when it is inaccurate (Marsh, Meade, & Roediger, Journal of Memory and Language 49:519-536, 2003), but how ubiquitous is this phenomenon? In two experiments, we investigated whether this tendency to encode and rely on inaccuracies from text might be influenced by the plausibility of misinformation. In Experiment 1, we presented stories containing inaccurate plausible statements (e.g., "The Pilgrims' ship was the Godspeed"), inaccurate implausible statements (e.g., . . . the Titanic), or accurate statements (e.g., . . . the Mayflower). On a subsequent test of general knowledge, participants relied significantly less on implausible than on plausible inaccuracies from the texts but continued to rely on accurate information. In Experiment 2, we replicated these results with the addition of a think-aloud procedure to elicit information about readers' noticing and evaluative processes for plausible and implausible misinformation. Participants indicated more skepticism and less acceptance of implausible than of plausible inaccuracies. In contrast, they often failed to notice, completely ignored, and at times even explicitly accepted the misinformation provided by plausible lures. These results offer insight into the conditions under which reliance on inaccurate information occurs and suggest potential mechanisms that may underlie reported misinformation effects. PMID:24005790

  20. Improved delivery through biological membranes. XXXVII. Synthesis and stability of novel redox derivatives of naproxen and indomethacin.

    PubMed

    Phelan, M J; Bodor, N

    1989-08-01

    Several novel bioreversible redox derivatives of the nonsteroida, antinflammatory drugs (NSAID) naproxen and indomethacin were synthesized. The stability of these dihydropyridine-NSAID derivatives their synthetic precursors, and predicted products of oxidative metabolism, the corresponding pyridinium salts, was determined in buffer, human and rat blood, and rat organ homogenate. The dihydropyridines exhibited the expected stability profiles in the media examined: oxidation, water addition, and/or ester hydrolysis. The corresponding pyridinium salts were quite stable in biomedia. ester hydrolysis being the primary route of decomposition. The results of this study may be useful in selecting suitable candidates for selective delivery of naproxen and indomethacin across the blood-brain barrier. PMID:2813259

  1. Tebipenem pivoxyl. Derivative spectroscopy study of stability of the first oral carbapenem

    NASA Astrophysics Data System (ADS)

    Cielecka-Piontek, Judyta; Paczkowska, Magdalena; Zalewski, Przemysław; Talaczyńska, Alicja; Mizera, Mikołaj

    2015-01-01

    A simple and selective derivative spectrophotometric method was developed for the quantitative determination of tebipenem and its pivoxyl ester in the presence of degradation products formed during degradation in aqueous solutions (hydrolysis, oxidation, phosphate buffer pH ∼6.0) and in the solid state (photolysis, thermolysis in dry air and at an increased relative air humidity). The method was based on zero-crossing first-derivative spectrophotometry (λ = 341 nm for tebipenem pivoxyl and λ = 320 nm for tebipenem), which eliminated the overlapping caused by various degradation products. The selectivity of the method for determination of tebipenem pivoxyl and tepipenem during stability studies was an effect of lack of substituents containing π-bond system chromophores in degradation products. It was also confirmed by comparison of the experimental spectra sample with the theoretical UV spectra and their first derivatives which were obtained by using the density functional theory with the B3LYP hybrid functional and 6-31G(d,p) basis set. The method were linear in the concentration range 16.70-220.0 μg mL-1 for tebipenem (λ = 320 nm; r = 0.9989) and 10.70-160.0 μg mL-1 for tebipenem pivoxyl (λ = 341 nm, r = 0.9990). The limits of detection and quantitation were 4.72 and 15.60 μg mL-1 for tebipenem and 2.54 and 8.40 μg mL-1 for tebipenem pivoxyl, respectively. The method had a good intra-day precision (RSD from 0.12% to 0.62%) and inter-day precision (RSD from 0.22% to 2.13%). The recovery of tebipenem and tebipenem pivoxyl ranged from 99.61% to 99.86% and from 99.38% to 99.87%, respectively. First-derivative spectrophotometry was used for a routine analysis of tebipenem and its ester as well as to monitor the conversion of tebipenem pivoxyl to tebipenem and to predict their degradation pathways.

  2. Genetic Stability of Bacterial Artificial Chromosome-Derived Human Cytomegalovirus during Culture In Vitro

    PubMed Central

    Murrell, Isa; Wilkie, Gavin S.; Davison, Andrew J.; Statkute, Evelina; Fielding, Ceri A.; Tomasec, Peter; Wilkinson, Gavin W. G.

    2016-01-01

    tropism, more susceptible to natural killer cells, and less pathogenic. Following isolation from clinical material, HCMV genomes can be stabilized by cloning into bacterial artificial chromosomes (BACs), and then virus is regenerated by DNA transfection. However, mutations can occur not only during isolation prior to BAC cloning but also when virus is regenerated. We have identified conditions under which BAC-derived viruses containing an intact, wild-type genome can be propagated in vitro with minimal risk of mutants being selected, enabling studies of viruses expressing the gene complement of a clinical strain. However, even under these optimized conditions, sporadic mutations can occur, highlighting the advisability of sequencing the HCMV stocks used in experiments. PMID:26842472

  3. Stability of Hydroxycinnamic Acid Derivatives, Flavonol Glycosides, and Anthocyanins in Black Currant Juice.

    PubMed

    Mäkilä, Leenamaija; Laaksonen, Oskar; Alanne, Aino-Liisa; Kortesniemi, Maaria; Kallio, Heikki; Yang, Baoru

    2016-06-01

    The stability of phenolic compounds was followed in black currant juice at ambient temperatures (in light and in dark conditions) and at +4 °C for a year. Analyses were based on high-performance liquid chromatography-diode-array detection-electrospray ionization-mass spectrometry (or tandem mass spectrometry) and high-performance liquid chromatography-diode-array detection-electrospray ionization-quadrupole time-of-flight mass spectrometry methods supported by nuclear magnetic resonance after selective high-performance liquid chromatography isolation. Altogether, 43 metabolites were identified, of which 2-(Z)-p-coumaroyloxymethylene-4-β-d-glucopyranosyloxy-2-(Z)-butenenitrile, 2-(E)-caffeoyloxymethylene-4-β-d-glucopyranosyloxy-2-(Z)-butenenitrile, 1-O-(Z)-p-coumaroyl-β-d-glucopyranose, (Z)-p-coumaric acid 4-O-β-d-glucopyranoside, and (Z)-p-coumaric acid were novel findings in black currant juice. Hydroxycinnamic acid derivatives degraded 20-40% at room temperature during one year of storage, releasing free hydroxycinnamic acids. O-Glucosides of hydroxycinnamic acid compounds were the most stable, followed by O-acylquinic acids, acyloxymethyleneglucosyloxybutenenitriles, and O-acylglucoses. Light induced the isomerization of (E)-coumaric acid compounds into corresponding Z-isomers. Flavonol glycosides stayed fairly stable. Flavonol aglycones were derived mainly from malonylglucosides. Over 90% of anthocyanins were lost at room temperature in a year, practically independent of light. Storage at low temperatures, preferably excluding light, is necessary to retain the original composition of phenolic compounds. PMID:27147482

  4. Stabilization of asphaltenes in aliphatic solvents using alkylbenzene-derived amphiphiles. 1. Effect of the chemical structure of amphiphiles on asphaltene stabilization

    SciTech Connect

    Chang, C.L.; Fogler, H.S. )

    1994-06-01

    Stabilization of crude oil asphaltenes in apolar alkane solvents was investigated using a series of alkylbenzene-derived amphiphiles as the asphaltene stabilizers. In this paper (i.e., part I), we present the study on the influences of the chemical structure of these amphiphiles on the effectiveness of asphaltene solubilization and on the strength of asphaltene-amphiphile interaction using both UV/vis and FTIR spectroscopies. The results showed that the amphiphile's effectiveness of asphaltene stabilization was primarily controlled by the polarity of the amphiphile's head group and the length of the amphiphile's alkyl tail. Increasing the acidity of the amphiphile's head group could promote the amphiphile's ability to stabilize asphaltenes by increasing the acid-base attraction between asphaltenes and amphiphiles. On the other hand, although decreasing the amphiphile's tail length increased the asphaltene-amphiphile attraction slightly, it still required a minimum tail length (six carbons for p-alkylphenol amphiphiles) for amphiphiles to form stable steric layers around asphaltenes. We also found additional acidic side groups of amphiphiles could further improve the amphiphile's ability to stabilize asphaltenes. The effect of the molecular weight of alkane solvents on the amphiphile's ability to stabilize asphaltenes was also studied. 18 refs., 12 figs., 3 tabs.

  5. Immobilization-stabilization of proteins on nanofibrillated cellulose derivatives and their bioactive film formation.

    PubMed

    Arola, Suvi; Tammelin, Tekla; Setälä, Harri; Tullila, Antti; Linder, Markus B

    2012-03-12

    In a number of different applications for enzymes and specific binding proteins a key technology is the immobilization of these proteins to different types of supports. In this work we describe a concept for protein immobilization that is based on nanofibrillated cellulose (NFC). NFC is a form of cellulose where fibers have been disintegrated into fibrils that are only a few nanometers in diameter and have a very large aspect ratio. Proteins were conjugated through three different strategies using amine, epoxy, and carboxylic acid functionalized NFC. The conjugation chemistries were chosen according to the reactive groups on the NFC derivatives; epoxy amination, heterobifunctional modification of amino groups, and EDC/s-NHS activation of carboxylic acid groups. The conjugation reactions were performed in solution and immobilization was performed by spin coating the protein-NCF conjugates. The structure of NFC was shown to be advantageous for both protein performance and stability. The use of NFC allows all covalent chemistry to be performed in solution, while the immobilization is achieved by a simple spin coating or spreading of the protein-NFC conjugates on a support. This allows more scalable methods and better control of conditions compared to the traditional methods that depend on surface reactions. PMID:22248303

  6. Gamma-radiolytic stability of new methylated TODGA derivatives for minor actinide recycling.

    PubMed

    Galán, Hitos; Zarzana, Christopher A; Wilden, Andreas; Núñez, Ana; Schmidt, Holger; Egberink, Richard J M; Leoncini, Andrea; Cobos, Joaquín; Verboom, Willem; Modolo, Giuseppe; Groenewold, Gary S; Mincher, Bruce J

    2015-11-01

    The stability against gamma radiation of MeTODGA (methyl tetraoctyldiglycolamide) and Me2TODGA (dimethyl tetraoctyldiglycolamide), derivatives from the well-known extractant TODGA (N,N,N',N'-tetraoctyldiglycolamide), were studied and compared. Solutions of MeTODGA and Me2TODGA in alkane diluents were subjected to (60)Co γ-irradiation in the presence and absence of nitric acid and analyzed using LC-MS to determine their rates of radiolytic concentration decrease, as well as to identify radiolysis products. The results of product identification from three different laboratories are compared and found to be in good agreement. The diglycolamide (DGA) concentrations decreased exponentially with increasing absorbed dose. The MeTODGA degradation rate constants (dose constants) were uninfluenced by the presence of nitric acid, but the acid increased the rate of degradation for Me2TODGA. The degradation products formed by irradiation are also initially produced in greater amounts in acid-contacted solution, but products may also be degraded by continued radiolysis. The identified radiolysis products suggest that the weakest bonds are those in the diglycolamide center of these molecules. PMID:26412572

  7. Gamma-radiolytic stability of new methylated TODGA derivatives for minor actinide recycling

    DOE PAGESBeta

    Galan, Hitos; Zarzana, Christopher A.; Wilden, Andreas; Nunez, Ana; Schmidt, Holger; Egberink, Richard J. M.; Leoncini, Andrea; Cobos, Joaquin; Verboom, Willem; Modolo, Giuseppe; et al

    2015-09-15

    The stability against gamma radiation of MeTODGA (methyl tetraoctyldiglycolamide) and Me2TODGA (dimethyl tetraoctyldiglycolamide), derivatives from the well-known extractant TODGA (N,N,N',N';-tetraoctyldiglycolamide), were studied and compared. Solutions of MeTODGA and Me2TODGA in alkane diluents were subjected to 60Co γ-irradiation in the presence and absence of nitric acid and analyzed using LC-MS to determine their rates of radiolytic concentration decrease, as well as to identify radiolysis products. The results of product identification from three different laboratories are compared and found to be in good agreement. The diglycolamide (DGA) concentrations decreased exponentially with increasing absorbed dose. The MeTODGA degradation rate constants (dose constants) weremore » uninfluenced by the presence of nitric acid, but the acid increased the rate of degradation for Me2TODGA. The degradation products formed by irradiation are also initially produced in greater amounts in acid-contacted solution, but products may also be degraded by continued radiolysis. As a result, the identified radiolysis products suggest that the weakest bonds are those in the diglycolamide center of these molecules.« less

  8. Gamma-radiolytic stability of new methylated TODGA derivatives for minor actinide recycling

    SciTech Connect

    Galan, Hitos; Zarzana, Christopher A.; Wilden, Andreas; Nunez, Ana; Schmidt, Holger; Egberink, Richard J. M.; Leoncini, Andrea; Cobos, Joaquin; Verboom, Willem; Modolo, Giuseppe; Groenewold, Gary S.; Mincher, Bruce J.

    2015-09-15

    The stability against gamma radiation of MeTODGA (methyl tetraoctyldiglycolamide) and Me2TODGA (dimethyl tetraoctyldiglycolamide), derivatives from the well-known extractant TODGA (N,N,N',N';-tetraoctyldiglycolamide), were studied and compared. Solutions of MeTODGA and Me2TODGA in alkane diluents were subjected to 60Co γ-irradiation in the presence and absence of nitric acid and analyzed using LC-MS to determine their rates of radiolytic concentration decrease, as well as to identify radiolysis products. The results of product identification from three different laboratories are compared and found to be in good agreement. The diglycolamide (DGA) concentrations decreased exponentially with increasing absorbed dose. The MeTODGA degradation rate constants (dose constants) were uninfluenced by the presence of nitric acid, but the acid increased the rate of degradation for Me2TODGA. The degradation products formed by irradiation are also initially produced in greater amounts in acid-contacted solution, but products may also be degraded by continued radiolysis. As a result, the identified radiolysis products suggest that the weakest bonds are those in the diglycolamide center of these molecules.

  9. The Effects of Test Order and Nodal Distance on the Emergence and Stability of Derived Discriminative Stimulus Functions

    ERIC Educational Resources Information Center

    Rehfeldt, Ruth Anne; Dymond, Simon

    2005-01-01

    The present study examined the effects of equivalence test order and nodal distance on the emergence and stability of derived discriminative stimulus functions. Participants in 1 group were exposed to a transfer of functions test following a symmetry and equivalence test, another group of participants completed a symmetry and equivalence test…

  10. Calculation of lateral-directional stability derivatives of wings by a nonplanar quasi-vortex-lattice method

    NASA Technical Reports Server (NTRS)

    Lan, C. E.

    1981-01-01

    The nonplanar quasi-vortex-lattice method is applied to the calculation of lateral-directional stability derivatives of wings with and without vortex-lift effect. Results for conventional configurations and those with winglets, V-tail, etc. are compared with available data. All rolling moment derivatives are found to be accurately predicted. The prediction of side force and yawing moment derivatives for some configurations is not as accurate. Causes of the discrepancy are discussed. A user's manual for the program and the program listing are also included.

  11. Is semantic preview benefit due to relatedness or plausibility?

    PubMed

    Veldre, Aaron; Andrews, Sally

    2016-07-01

    There is increasing evidence that skilled readers of English benefit from processing a parafoveal preview of a semantically related word. However, in previous investigations of semantic preview benefit using the gaze-contingent boundary paradigm the semantic relatedness between the preview and target has been confounded with the plausibility of the preview word in the sentence. In the present study, preview relatedness and plausibility were independently manipulated in neutral sentences read by a large sample of skilled adult readers. Participants were assessed on measures of reading and spelling ability to identify possible sources of individual differences in preview effects. The results showed that readers benefited from a preview of a plausible word, regardless of the semantic relatedness of the preview and the target. However, there was limited evidence of a semantic relatedness benefit when the plausibility of the preview was controlled. The plausibility preview benefit was strongest for low proficiency readers, suggesting that poorer readers were more likely to program a forward saccade based on information extracted from the preview. High proficiency readers showed equivalent disruption from all nonidentical previews suggesting that they were more likely to suffer interference from the orthographic mismatch between preview and target. (PsycINFO Database Record PMID:26752734

  12. Performance, methanol tolerance and stability of Fe-aminobenzimidazole derived catalyst for direct methanol fuel cells

    NASA Astrophysics Data System (ADS)

    Sebastián, David; Serov, Alexey; Artyushkova, Kateryna; Atanassov, Plamen; Aricò, Antonino S.; Baglio, Vincenzo

    2016-07-01

    Highly active and durable non-platinum group metals (non-PGM) catalyst based on iron-nitrogen-carbon (Fe-N-C) for the oxygen reduction reaction (ORR) derived from pyrolyzed Fe-aminobenzimidazole (Fe-ABZIM) was synthesized by sacrificial support method (SSM), and characterized by several physical-chemical techniques: scanning electron microscopy, transmission electron microscopy, Brunauer-Emmett-Teller method and X-ray photoelectron spectroscopy. In half-cell electrochemical configuration, the Fe-ABZIM catalyst presented a significant improvement of ORR activity with respect to a recently reported non-PGM formulation based on Fe-aminoantipyrine, with an enhancement of half-wave potential of about 85 mV in O2-saturated sulfuric acid solution. To the moment, the gap with respect to a benchmark Pt/C catalyst was about 90 mV. The Fe-ABZIM catalyst showed a remarkably high tolerance to methanol, resulting in superior ORR performance compared to Pt/C at methanol concentrations higher than 0.02 M. In direct methanol fuel cell (DMFC) good performances were also obtained. A durability test (100 h) at 90 °C, feeding 5 M methanol, was carried out. A certain decrease of performance was recorded, amounting to -0.20 mW cm-2 h-1 at the very beginning of test and -0.05 mW cm-2 h-1 at the end. However, the Fe-ABZIM is more adequate than previously reported formulations in terms of both ORR activity and stability.

  13. Choosing from Plausible Alternatives in Interpreting Qualitative Data.

    ERIC Educational Resources Information Center

    Donmoyer, Robert

    This paper addresses a variation of the traditional validity question asked of qualitative researchers. Here the question is not "How do we know the qualitative researcher's question is valid?" but rather, "How does the qualitative researcher choose from among a multitude of apparently valid or at least plausible interpretations?" As early as…

  14. Plausibility: Is There a Place for It in Chemistry Teaching?

    ERIC Educational Resources Information Center

    MacDonald, J. J.

    1991-01-01

    Some of the persistent misinformation offered to secondary students while studying chemistry is discussed. A few cases where plausibility, knowingly or otherwise, has been offered to students instead of the accurate explanation are described. Concepts of charge, current, the mole, amount, rates, activation energy, sign convention in voltaic cells,…

  15. Polycyclic Aromatic Hydrocarbons as Plausible Prebiotic Membrane Components

    NASA Astrophysics Data System (ADS)

    Groen, Joost; Deamer, David W.; Kros, Alexander; Ehrenfreund, Pascale

    2012-08-01

    Aromatic molecules delivered to the young Earth during the heavy bombardment phase in the early history of our solar system were likely to be among the most abundant and stable organic compounds available. The Aromatic World hypothesis suggests that aromatic molecules might function as container elements, energy transduction elements and templating genetic components for early life forms. To investigate the possible role of aromatic molecules as container elements, we incorporated different polycyclic aromatic hydrocarbons (PAH) in the membranes of fatty acid vesicles. The goal was to determine whether PAH could function as a stabilizing agent, similar to the role that cholesterol plays in membranes today. We studied vesicle size distribution, critical vesicle concentration and permeability of the bilayers using C6-C10 fatty acids mixed with amphiphilic PAH derivatives such as 1-hydroxypyrene, 9-anthracene carboxylic acid and 1,4 chrysene quinone. Dynamic Light Scattering (DLS) spectroscopy was used to measure the size distribution of vesicles and incorporation of PAH species was established by phase-contrast and epifluorescence microscopy. We employed conductimetric titration to determine the minimal concentration at which fatty acids could form stable vesicles in the presence of PAHs. We found that oxidized PAH derivatives can be incorporated into decanoic acid (DA) vesicle bilayers in mole ratios up to 1:10 (PAH:DA). Vesicle size distribution and critical vesicle concentration were largely unaffected by PAH incorporation, but 1-hydroxypyrene and 9-anthracene carboxylic acid lowered the permeability of fatty acid bilayers to small solutes up to 4-fold. These data represent the first indication of a cholesterol-like stabilizing effect of oxidized PAH derivatives in a simulated prebiotic membrane.

  16. Polycyclic aromatic hydrocarbons as plausible prebiotic membrane components.

    PubMed

    Groen, Joost; Deamer, David W; Kros, Alexander; Ehrenfreund, Pascale

    2012-08-01

    Aromatic molecules delivered to the young Earth during the heavy bombardment phase in the early history of our solar system were likely to be among the most abundant and stable organic compounds available. The Aromatic World hypothesis suggests that aromatic molecules might function as container elements, energy transduction elements and templating genetic components for early life forms. To investigate the possible role of aromatic molecules as container elements, we incorporated different polycyclic aromatic hydrocarbons (PAH) in the membranes of fatty acid vesicles. The goal was to determine whether PAH could function as a stabilizing agent, similar to the role that cholesterol plays in membranes today. We studied vesicle size distribution, critical vesicle concentration and permeability of the bilayers using C(6)-C(10) fatty acids mixed with amphiphilic PAH derivatives such as 1-hydroxypyrene, 9-anthracene carboxylic acid and 1,4 chrysene quinone. Dynamic Light Scattering (DLS) spectroscopy was used to measure the size distribution of vesicles and incorporation of PAH species was established by phase-contrast and epifluorescence microscopy. We employed conductimetric titration to determine the minimal concentration at which fatty acids could form stable vesicles in the presence of PAHs. We found that oxidized PAH derivatives can be incorporated into decanoic acid (DA) vesicle bilayers in mole ratios up to 1:10 (PAH:DA). Vesicle size distribution and critical vesicle concentration were largely unaffected by PAH incorporation, but 1-hydroxypyrene and 9-anthracene carboxylic acid lowered the permeability of fatty acid bilayers to small solutes up to 4-fold. These data represent the first indication of a cholesterol-like stabilizing effect of oxidized PAH derivatives in a simulated prebiotic membrane. PMID:22798228

  17. Peroxidase-like activity of gold nanoparticles stabilized by hyperbranched polyglycidol derivatives over a wide pH range.

    PubMed

    Drozd, Marcin; Pietrzak, Mariusz; Parzuchowski, Paweł; Mazurkiewicz-Pawlicka, Marta; Malinowska, Elżbieta

    2015-12-11

    The aim of this work was to carry out comparative studies on the peroxidase-like activity of gold nanoparticles (AuNPs) stabilized with low molecular weight hyperbranched polyglycidol (HBPG-OH) and its derivative modified with maleic acid residues (HBPG-COOH). The influence of the stabilizer to gold precursor ratio on the size and morphology of nanoparticles obtained was checked, and prepared nanoparticles were characterized by means of transmission electron microscopy and UV-Vis spectroscopy. The results indicated the divergent effect of increasing the concentration of stabilizers (HBPG-OH or HBPG-COOH) on the size of the nanostructures obtained. The gold nanoparticles obtained were characterized as having intrinsic peroxidase-like activity and the mechanism of catalysis in acidic and alkaline mediums was consistent with the standard Michaelis-Menten kinetics, revealing a strong affinity of AuNPs with 2, 2'-azino-bis(3-ethylbenzothiazoline-6-sulfonic acid) (ABTS) and 3, 3', 5, 5'-tetramethylbenzidine (TMB), and significantly lower affinity towards phenol. By comparing the kinetic parameters, a negligible effect of polymeric ligand charge on activity against various types of substrates (anionic or cationic) was indicated. The superiority of steric stabilization via the application of tested low-weight hyperbranched polymers over typical stabilizers in preventing salt-induced aggregation and maintaining high catalytic activity in time was proved. The applied hyperbranched stabilizers provide a good tool for manufacturing gold-based nanozymes, which are highly stable and active over a wide pH range. PMID:26567596

  18. Corrosion and stability study of Bacillus thuringiensis var. kurstaki starch industry wastewater-derived biopesticide formulation.

    PubMed

    Gnepe, Jean R; Tyagi, Rajeshwar D; Brar, Satinder K; Valéro, José R; Surampalli, Rao Y

    2014-01-01

    Biopesticides are usually sprayed on forests by using planes made up of aluminum alloy. Bioval derived from starch industry wastewater (SIW) in suspension form was developed as stable anticorrosive biopesticide formulation. In this context, various anticorrosion agents such as activated charcoal, glycerin, ethylene glycol, phytic acid, castor oil and potassium silicate were tested as anticorrosive agents. There was no corrosion found in Bioval formulation where potassium silicate (0.5% w/v) was added and compared with Foray 76 B, as an industrial standard, when stored over 6 months. In relation to other parameters, the anticorrosion formulation of Bioval+buffer+KSi reported excellent zeta potential (-33.19 ± 4 mV) and the viscosity (319.13 ± 32 mPa.s) proving it's stability over 6 months, compared to the standard biopesticide Foray 76 B (-36.62 ± 4 mV potential zeta, pH 4.14 ± 0.1 and 206 ± 21 mPa.s viscosity). Metal analysis of the different biopesticides showed that Bioval+buffer+KSi has no corrosion (5.11 ± 0.5 mg kg(-1) of Al and 13.53 ± 1.5 mg kg(-1) of Fe) on the aluminum alloy due to the contribution of sodium acetate buffer at pH 5. The bioassays reported excellent results for Bioval+Buffer+KSi (2.95 ± 0.3 × 10(9) CFU mL(-1) spores and 26.6 ± 2.7 × 10(9) IU L(-1) Tx) compared with initial Bioval (2.46 ± 0.3 × 10(9) CFU mL(-1) spores and 23.09 ± 3 × 10(9) IU L(-1) Tx) and Foray 76 B (2.3 ± 0.2 × 10(9) CFU mL(-1) spores and 19.950 ± 2.1 UI L(-1) Tx) which was due to the break-up of the external chitinous membrane due to abrasive action of potassium silicate after ingestion by insects. The contribution of sodium acetate buffer and potassium silicate (0.5% and at pH = 5) as anticorrosion agent in the Bioval allowed production of an efficient biopesticide with a reduced viscosity and favorable pH as compared to Foray 76 B which enhanced the entomotoxic potential against spruce budworm (SB) larvae (Lepidoptera: Choristoneura fumiferana

  19. Navier-Stokes predictions of dynamic stability derivatives for air-breathing hypersonic vehicle

    NASA Astrophysics Data System (ADS)

    Liu, Xu; Liu, Wei; Zhao, Yunfei

    2016-01-01

    Dynamic derivatives are important parameters for designing vehicle trajectory and attitude control system that directly decide the divergence behavior of vibration of the aircraft open-loop system under interference. After calibration model validation, the dynamic behavior of air-breathing hypersonic vehicle WR-A is characterized. The unsteady flow field of aircraft forced simple harmonic vibration (SHV) is simulated using N-S equation. The direct damping derivatives, cross derivatives, acceleration derivatives and rotary derivatives of WR-A under different frequencies, amplitudes and positions of centroid are obtained. Research demonstrates that the proportion of acceleration derivatives, which represents the flow time lag effect, in the direct damping derivatives can be as high as 40% but is opposite to the damping derivative value symbols in some cases, contributing to dynamic instability. Numerical simulation on large-amplitude forced vibration of WR-A indicates that the aerodynamic behavior predicted by the dynamic derivative model agrees well with unsteady calculations. The inlet performance parameter derivatives are solved using the Etkin theory. The inlet performance parameters under large-amplitude vibration are successfully predicted using the dynamic derivative model. This offers a guideline for characterizing the dynamic internal flow field and unsteady inlet performance.

  20. Determination of lateral-stability derivatives and transfer-function coefficients from frequency-response data for lateral motions

    NASA Technical Reports Server (NTRS)

    Donegan, James J; Robinson, Samuel W , Jr; Gates, Ordway, B , jr

    1955-01-01

    A method is presented for determining the lateral-stability derivatives, transfer-function coefficients, and the modes for lateral motion from frequency-response data for a rigid aircraft. The method is based on the application of the vector technique to the equations of lateral motion, so that the three equations of lateral motion can be separated into six equations. The method of least squares is then applied to the data for each of these equations to yield the coefficients of the equations of lateral motion from which the lateral-stability derivatives and lateral transfer-function coefficients are computed. Two numerical examples are given to demonstrate the use of the method.

  1. Solute-Derived Thermal Stabilization of Nano-sized Grains in Melt-Spun Aluminum

    NASA Astrophysics Data System (ADS)

    Baker, A. H.; Sanders, P. G.; Lass, E. A.; Kapoor, Deepak; Kampe, S. L.

    2016-08-01

    Thermal stabilization of nanograined metallic microstructures (or nanostructures) can be difficult due to the large driving force for growth that arises from the inherently significant boundary area. Kinetic approaches for stabilization of the nanostructure effective at low homologous temperatures often fail at higher homologous temperatures. Alternatively, thermodynamic approaches for thermal stabilization may offer higher temperature stability. In this research, modest alloying of aluminum with solute (1 pct by mole Sc, Yb, or Sr) was examined as a means to thermodynamically stabilize a bulk nanostructure at elevated temperatures. Following 1-hour annealing treatments at 673 K (400 °C) (0.72 Tm), 773 K (500 °C) (0.83 Tm), and 873 K (600 °C) (0.94 Tm), the alloys remain nanocrystalline (<100 nm) as measured by Warren-Averbach Fourier analysis of X-ray diffraction peaks and direct observation of TEM dark-field micrographs, with the efficacy of stabilization: Sr ≈ Yb > Sc. The disappearance of intermetallic phases in the Sr- and Yb-containing alloys in the X-ray diffraction spectra is observed to occur coincident with the stabilization after annealing, suggesting that precipitates dissolve and the boundaries are enriched with solute.

  2. Solute-Derived Thermal Stabilization of Nano-sized Grains in Melt-Spun Aluminum

    NASA Astrophysics Data System (ADS)

    Baker, A. H.; Sanders, P. G.; Lass, E. A.; Kapoor, Deepak; Kampe, S. L.

    2016-06-01

    Thermal stabilization of nanograined metallic microstructures (or nanostructures) can be difficult due to the large driving force for growth that arises from the inherently significant boundary area. Kinetic approaches for stabilization of the nanostructure effective at low homologous temperatures often fail at higher homologous temperatures. Alternatively, thermodynamic approaches for thermal stabilization may offer higher temperature stability. In this research, modest alloying of aluminum with solute (1 pct by mole Sc, Yb, or Sr) was examined as a means to thermodynamically stabilize a bulk nanostructure at elevated temperatures. Following 1-hour annealing treatments at 673 K (400 °C) (0.72 Tm), 773 K (500 °C) (0.83 Tm), and 873 K (600 °C) (0.94 Tm), the alloys remain nanocrystalline (<100 nm) as measured by Warren-Averbach Fourier analysis of X-ray diffraction peaks and direct observation of TEM dark-field micrographs, with the efficacy of stabilization: Sr ≈ Yb > Sc. The disappearance of intermetallic phases in the Sr- and Yb-containing alloys in the X-ray diffraction spectra is observed to occur coincident with the stabilization after annealing, suggesting that precipitates dissolve and the boundaries are enriched with solute.

  3. Calculation of lateral-directional stability derivatives for wing-body combinations with and without jet-interaction effects

    NASA Technical Reports Server (NTRS)

    Lan, C. E.

    1977-01-01

    A theoretical method is presented for predicting the lateral-directional stability derivatives of wing-body combinations with or without the blowing jet effect. The fuselage effect is accounted for by the axial distribution of vortex multiplets. Comparison of the predicted results with experiments and other theoretical methods show good agreement for configurations without the blowing jet. More applicable experimental data with blowing jets are needed to establish the accuracy of the theory.

  4. Interpreting a Graph and Constructing Its Derivative Graph: Stability and Change in Students' Conceptions

    ERIC Educational Resources Information Center

    Ubuz, Behiye

    2007-01-01

    This present study investigated engineering students' conceptions and misconceptions related to derivative, particularly interpreting the graph of a function and constructing its derivative graph. Participants were 147 first year engineering students from four universities enrolled in first year undergraduate calculus courses with or without the…

  5. Effects of substituents on tetracene derivatives on their stabilities and singlet fission.

    PubMed

    Shen, Li; Chen, Yuhan; Li, Xiyou; Gao, Jun

    2014-06-01

    Tetracene is well known for its high singlet fission (SF) efficiency, which could be used to enhance the energy conversion efficiency in solar cells. However, its photoinstability toward oxygen must be improved before it can be used as a light-harvesting component. In this work, a series of substituted tetracenes were designed to identify tetracene compounds with not only good stability toward oxidation but also small SF activation energies. The stabilities were evaluated using the frontier molecular orbital energies, whereas the SF activation energies were deduced from the energy differences between the first excited singlet state and twice the first excited triplet state. Substitution strategies on tetracene are proposed for the purpose of simultaneously improving stability and reducing the SF activation energy. PMID:24863343

  6. Denatured state aggregation parameters derived from concentration dependence of protein stability.

    PubMed

    Schön, Arne; Clarkson, Benjamin R; Siles, Rogelio; Ross, Patrick; Brown, Richard K; Freire, Ernesto

    2015-11-01

    Protein aggregation is a major issue affecting the long-term stability of protein preparations. Proteins exist in equilibrium between the native and denatured or partially denatured conformations. Often denatured or partially denatured conformations are prone to aggregate because they expose to solvent the hydrophobic core of the protein. The aggregation of denatured protein gradually shifts the protein equilibrium toward increasing amounts of denatured and ultimately aggregated protein. Recognizing and quantitating the presence of denatured protein and its aggregation at the earliest possible time will bring enormous benefits to the identification and selection of optimal solvent conditions or the engineering of proteins with the best stability/aggregation profile. In this article, a new approach that allows simultaneous determination of structural stability and the amount of denatured and aggregated protein is presented. This approach is based on the analysis of the concentration dependence of the Gibbs energy (ΔG) of protein stability. It is shown that three important quantities can be evaluated simultaneously: (i) the population of denatured protein, (ii) the population of aggregated protein, and (iii) the fraction of denatured protein that is aggregated. PMID:26239214

  7. Genomic stability of Palmer amaranth plants derived by macro-vegetative propagation

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Q-PCR (quantitative polymerase chain reaction) and random amplified polymorphic DNA (RAPD) were utilized to investigate genetic stability of Palmer amaranth cloned plants over 10 generations. Q-PCR analysis of DNA from parent Palmer amaranth plants was repeated and confidence levels for determining ...

  8. Peroxidase-like activity of gold nanoparticles stabilized by hyperbranched polyglycidol derivatives over a wide pH range

    NASA Astrophysics Data System (ADS)

    Drozd, Marcin; Pietrzak, Mariusz; Parzuchowski, Paweł; Mazurkiewicz-Pawlicka, Marta; Malinowska, Elżbieta

    2015-12-01

    The aim of this work was to carry out comparative studies on the peroxidase-like activity of gold nanoparticles (AuNPs) stabilized with low molecular weight hyperbranched polyglycidol (HBPG-OH) and its derivative modified with maleic acid residues (HBPG-COOH). The influence of the stabilizer to gold precursor ratio on the size and morphology of nanoparticles obtained was checked, and prepared nanoparticles were characterized by means of transmission electron microscopy and UV-Vis spectroscopy. The results indicated the divergent effect of increasing the concentration of stabilizers (HBPG-OH or HBPG-COOH) on the size of the nanostructures obtained. The gold nanoparticles obtained were characterized as having intrinsic peroxidase-like activity and the mechanism of catalysis in acidic and alkaline mediums was consistent with the standard Michaelis-Menten kinetics, revealing a strong affinity of AuNPs with 2, 2‧-azino-bis(3-ethylbenzothiazoline-6-sulfonic acid) (ABTS) and 3, 3‧, 5, 5‧-tetramethylbenzidine (TMB), and significantly lower affinity towards phenol. By comparing the kinetic parameters, a negligible effect of polymeric ligand charge on activity against various types of substrates (anionic or cationic) was indicated. The superiority of steric stabilization via the application of tested low-weight hyperbranched polymers over typical stabilizers in preventing salt-induced aggregation and maintaining high catalytic activity in time was proved. The applied hyperbranched stabilizers provide a good tool for manufacturing gold-based nanozymes, which are highly stable and active over a wide pH range.

  9. A parametric study of planform and aeroelastic effects on aerodynamic center, alpha- and q- stability derivatives. Appendix A: A computer program for calculating alpha- and q- stability derivatives and induced drag for thin elastic aeroplanes at subsonic and supersonic speeds

    NASA Technical Reports Server (NTRS)

    Roskam, J.; Lan, C.; Mehrotra, S.

    1972-01-01

    The computer program used to determine the rigid and elastic stability derivatives presented in the summary report is listed in this appendix along with instructions for its use, sample input data and answers. This program represents the airplane at subsonic and supersonic speeds as (a) thin surface(s) (without dihedral) composed of discrete panels of constant pressure according to the method of Woodward for the aerodynamic effects and slender beam(s) for the structural effects. Given a set of input data, the computer program calculates an aerodynamic influence coefficient matrix and a structural influence coefficient matrix.

  10. Properties of cationic monosubstituted tetraalkylammonium cyclodextrin derivatives - their stability, complexation ability in solution or when deposited on solid anionic surface.

    PubMed

    Popr, Martin; Filippov, Sergey K; Matushkin, Nikolai; Dian, Juraj; Jindřich, Jindřich

    2015-01-01

    The thermal stability of the monosubstituted cationic cyclodextrin (CD) derivatives PEMEDA-β-CD and PEMPDA-β-CD, which differ in their substituent linker length (ethylene and propylene, respectively), was studied via (1)H NMR experiments. PEMPDA-β-CD exhibited higher resistance towards the Hofmann degradation and was chosen as a more suitable host molecule for further studies. Inclusion properties of PEMPDA-β-CD in solution with a series of simple aromatic guests (salicylic acid, p-methoxyphenol and p-nitroaniline) were determined by isothermal titration calorimetry (ITC) and compared to the native β-CD. Permanently charged cationic CD derivatives were successfully deposited on the anionic solid surface of polymeric Nafion(®) 117 membrane via electrostatic interactions. Deposition kinetics and coverage of the surface were determined by ELSD. Finally, the ability of the CD derivatives bound to the solid surface to encapsulate aromatic compounds from aqueous solution was measured by UV-vis spectroscopy. The obtained results are promising for future industrial applications of the monosubstituted β-CD derivatives, because the preparation of cationic CD derivatives is applicable in large scale, without the need of chromatographic purification. Their ionic deposition on a solid surface is simple, yet robust and a straightforward process as well. PMID:25815069

  11. X-29A Lateral-Directional Stability and Control Derivatives Extracted From High-Angle-of-Attack Flight Data

    NASA Technical Reports Server (NTRS)

    Iliff, Kenneth W.; Wang, Kon-Sheng Charles Wang

    1996-01-01

    The lateral-directional stability and control derivatives of the X-29A number 2 are extracted from flight data over an angle-of-attack range of 4 degrees to 53 degrees using a parameter identification algorithm. The algorithm uses the linearized aircraft equations of motion and a maximum likelihood estimator in the presence of state and measurement noise. State noise is used to model the uncommanded forcing function caused by unsteady aerodynamics over the aircraft at angles of attack above 15 degrees. The results supported the flight-envelope-expansion phase of the X-29A number 2 by helping to update the aerodynamic mathematical model, to improve the real-time simulator, and to revise flight control system laws. Effects of the aircraft high gain flight control system on maneuver quality and the estimated derivatives are also discussed. The derivatives are plotted as functions of angle of attack and compared with the predicted aerodynamic database. Agreement between predicted and flight values is quite good for some derivatives such as the lateral force due to sideslip, the lateral force due to rudder deflection, and the rolling moment due to roll rate. The results also show significant differences in several important derivatives such as the rolling moment due to sideslip, the yawing moment due to sideslip, the yawing moment due to aileron deflection, and the yawing moment due to rudder deflection.

  12. An amphipathic polypeptide derived from poly-γ-glutamic acid for the stabilization of membrane proteins

    PubMed Central

    Han, Seong-Gu; Na, Jung-Hyun; Lee, Won-Kyu; Park, Dongkook; Oh, Jihye; Yoon, Sung-Ho; Lee, Cheng-Kang; Sung, Moon-Hee; Shin, Yeon-Kyun; Yu, Yeon Gyu

    2014-01-01

    Difficulties in the extraction of membrane proteins from cell membrane and their solubilization in native conformations have hindered their structural and biochemical analysis. To overcome these difficulties, an amphipathic polypeptide was synthesized by the conjugation of octyl and glucosyl groups to the carboxyl groups of poly-γ-glutamic acid (PGA). This polymer, called amphipathic PGA (APG), self-assembles as mono-disperse oligomers consisted of 4–5 monomers. APG shows significantly low value of critical micelle concentration and stabilization activity toward membrane proteins. Most of the sodium dodecyl sulfate (SDS)-solubilized membrane proteins from Escherichia coli remain soluble state in the presence of APG even after the removal of SDS. In addition, APG stabilizes purified 7 transmembrane proteins such as bacteriorhodopsin and human endothelin receptor Type A (ETA) in their active conformations. Furthermore, ETA in complex with APG is readily inserted into liposomes without disrupting the integrity of liposomes. These properties of APG can be applied to overcome the difficulties in the stabilization and reconstitution of membrane proteins. PMID:25283538

  13. Application of the conservation laws to the derivation of stability conditions for stationary flows of an ideal liquid

    NASA Astrophysics Data System (ADS)

    Vladimirov, V. A.

    1987-06-01

    A study is made of the motion integrals of an ideal incompressible liquid which are of interest from the standpoint of applications to the stability problem. The motion integrals are used to derive a functional which achieves its steady-state value over a given stationary flow. An analysis of the second variation shows that it has a fixed sign (flow is stable) only in the case of motion with symmetries. It is shown that general expressions for the second variation are integrals of linearized equations of motion. A generalization to the case of a stratified liquid is presented.

  14. Chemical stability and in vitro and clinical efficacy of a novel hybrid retinoid derivative, bis-retinamido methylpentane.

    PubMed

    Kim, Ki Hyun; Lim, Dae Gon; Lim, Jun Yeul; Kim, Nam Ah; Park, So-Hyun; Cho, Jin Hun; Shin, Beom Soo; Jeong, Seong Hoon

    2015-11-10

    The anti-aging agent, retinol, has fewer side effects and similar biological activity compared to retinoic acid. However, retinol becomes unstable when exposed to light and heat. A novel hybrid retinoid derivative, bis-retinamido methylpentane (RS-2A), was newly developed to overcome the limitations. This study evaluated the chemical stability of RS-2A under thermal and light conditions by examining degradation profiles, and assessed the in vitro biological activity, cytotoxicity, and clinical efficacy. Chemical stability and degradation profiles were investigated with HPLC and LC-MS. Especially, photo-stability of RS-2A was analyzed under various conditions, such as change of physical state and concentration, different solvents, and various excipients. For analyses of cellular activity and cytotoxicity, human dermal fibroblasts were cultured with RS-2A. To evaluate the safety and efficacy of the compound with the cellular results, RS-2A was applied to women who had moderate to severe wrinkles at the periorbital region. All of the experiments were conducted with retinol as a reference. RS-2A was more stable than retinol to thermal conditions, especially in solution. Both RS-2A and retinol were unstable to light, but RS-2A showed enhanced photo-stability with regard to concentration, more polar solvent, and addition of proper excipients. RS-2A exhibited decreased cytotoxicity and enhanced effects on collagen synthesis compared with retinol. In a clinical study, a 4-week treatment with RS-2A significantly improved the appearance of periorbital wrinkles without any side effects. The results indicate that RS-2A might have potential as an anti-aging agent for cosmeceutical preparations because of its enhanced chemical stability, biological activity, safety, and clinical efficacy. PMID:26325317

  15. Extraction of Lateral-Directional Stability and Control Derivatives for the Basic F-18 Aircraft at High Angles of Attack

    NASA Technical Reports Server (NTRS)

    Iliff, Kenneth W.; Wang, Kon-Sheng Charles

    1997-01-01

    The results of parameter identification to determine the lateral-directional stability and control derivatives of an F-18 research aircraft in its basic hardware and software configuration are presented. The derivatives are estimated from dynamic flight data using a specialized identification program developed at NASA Dryden Flight Research Center. The formulation uses the linearized aircraft equations of motions in their continuous/discrete form and a maximum likelihood estimator that accounts for both state and measurement noise. State noise is used to model the uncommanded forcing function caused by unsteady aerodynamics, such as separated and vortical flows, over the aircraft. The derivatives are plotted as functions of angle of attack between 3 deg and 47 deg and compared with wind-tunnel predictions. The quality of the derivative estimates obtained by parameter identification is somewhat degraded because the maneuvers were flown with the aircraft's control augmentation system engaged, which introduced relatively high correlations between the control variables and response variables as a result of control motions from the feedback control system.

  16. Prebiotically plausible mechanisms increase compositional diversity of nucleic acid sequences

    PubMed Central

    Derr, Julien; Manapat, Michael L.; Rajamani, Sudha; Leu, Kevin; Xulvi-Brunet, Ramon; Joseph, Isaac; Nowak, Martin A.; Chen, Irene A.

    2012-01-01

    During the origin of life, the biological information of nucleic acid polymers must have increased to encode functional molecules (the RNA world). Ribozymes tend to be compositionally unbiased, as is the vast majority of possible sequence space. However, ribonucleotides vary greatly in synthetic yield, reactivity and degradation rate, and their non-enzymatic polymerization results in compositionally biased sequences. While natural selection could lead to complex sequences, molecules with some activity are required to begin this process. Was the emergence of compositionally diverse sequences a matter of chance, or could prebiotically plausible reactions counter chemical biases to increase the probability of finding a ribozyme? Our in silico simulations using a two-letter alphabet show that template-directed ligation and high concatenation rates counter compositional bias and shift the pool toward longer sequences, permitting greater exploration of sequence space and stable folding. We verified experimentally that unbiased DNA sequences are more efficient templates for ligation, thus increasing the compositional diversity of the pool. Our work suggests that prebiotically plausible chemical mechanisms of nucleic acid polymerization and ligation could predispose toward a diverse pool of longer, potentially structured molecules. Such mechanisms could have set the stage for the appearance of functional activity very early in the emergence of life. PMID:22319215

  17. Assessing the plausibility of life on other worlds.

    PubMed

    Irwin, L N; Schulze-Makuch, D

    2001-01-01

    As the field of astrobiology matures and search strategies for life on other worlds are developed, the need to analyze in a systematic way the plausibility for life on other planetary systems becomes increasingly apparent. We propose the adoption of a simple plausibility of life (POL) rating system based on specific criteria. Category I applies to any body shown to have conditions essentially equivalent to those on Earth. Category II applies to bodies for which there is evidence of liquid water and sources of energy and where organic compounds have been detected or can reasonably be inferred (Mars, Europa). Category III applies to worlds where conditions are physically extreme but possibly capable of supporting exotic forms of life unknown on Earth (Titan, Triton). Category IV applies to bodies that could have seen the origin of life prior to the development of conditions so harsh as to make its perseverance at present unlikely but conceivable in isolated habitats (Venus, Io). Category V would be reserved for sites where conditions are so unfavorable for life by any reasonable definition that its origin or persistence there cannot be rated a realistic probability (the Sun, gas giant planets). The proposed system is intended to be generic. It assumes that life is based on polymeric chemistry occurring in a liquid medium with uptake and degradation of energy from the environment. Without any additional specific assumptions about the nature of life, the POL system is universally applicable. PMID:12467118

  18. Solvent-dependent optical limiting response of platinum nanoparticles stabilized by [60] fullerene derivative

    NASA Astrophysics Data System (ADS)

    Gao, Y. C.; He, C. Y.

    2015-05-01

    The optical limiting performance of platinum nanoparticle protected by C60 derivative in chloroform, ethanol and dimethylformamide (DMF) was measured with 532nm, 8ns duration laser pulses. Experiments showed that the optical limiting is solvent-dependent. The origins and solvent effect of the optical limiting were analyzed. It was proposed that the absorption-induced scattering is the main mechanism causing the optical limiting behavior and solvent effect.

  19. Electroweak vacuum stability and inflation via nonminimal derivative couplings to gravity

    NASA Astrophysics Data System (ADS)

    Di Vita, Stefano; Germani, Cristiano

    2016-02-01

    We show that the standard model vacuum can be stabilized if all particle propagators are nonminimally coupled to gravity. This is due to a Higgs-background dependent redefinition of the standard model fields: in terms of canonical variables and in the large Higgs field limit, the quantum fluctuations of the redefined fields are suppressed by the Higgs background. Thus, in this regime, quantum corrections to the tree-level electroweak potential are negligible. Finally, we show that in this framework the Higgs boson can be responsible for inflation. Due to a numerical coincidence that originates from the CMB data, inflation can happen if the Higgs boson mass, the top mass, and the QCD coupling lie in a region of the parameter space approximately equivalent than the one allowing for electroweak vacuum stability in the standard Model. We find some (small) regions in the standard model parameter space in which the new interaction "rescues" the electroweak vacuum, which would not be stable in the standard model.

  20. An integer order approximation method based on stability boundary locus for fractional order derivative/integrator operators.

    PubMed

    Deniz, Furkan Nur; Alagoz, Baris Baykant; Tan, Nusret; Atherton, Derek P

    2016-05-01

    This paper introduces an integer order approximation method for numerical implementation of fractional order derivative/integrator operators in control systems. The proposed method is based on fitting the stability boundary locus (SBL) of fractional order derivative/integrator operators and SBL of integer order transfer functions. SBL defines a boundary in the parametric design plane of controller, which separates stable and unstable regions of a feedback control system and SBL analysis is mainly employed to graphically indicate the choice of controller parameters which result in stable operation of the feedback systems. This study reveals that the SBL curves of fractional order operators can be matched with integer order models in a limited frequency range. SBL fitting method provides straightforward solutions to obtain an integer order model approximation of fractional order operators and systems according to matching points from SBL of fractional order systems in desired frequency ranges. Thus, the proposed method can effectively deal with stability preservation problems of approximate models. Illustrative examples are given to show performance of the proposed method and results are compared with the well-known approximation methods developed for fractional order systems. The integer-order approximate modeling of fractional order PID controllers is also illustrated for control applications. PMID:26876378

  1. Advances in assessing geomorphic plausibility in statistical susceptibility modelling

    NASA Astrophysics Data System (ADS)

    Steger, Stefan; Brenning, Alexander; Bell, Rainer; Petschko, Helene; Glade, Thomas

    2014-05-01

    ). The error estimation was conducted by applying (non-spatial) holdout and spatial cross-validation. Geomorphic plausibility was estimated by subjectively assessing the geomorphic situation shown in a high resolution hillshade and comparing this evaluation with the ranking of the final susceptibility maps. For instance, high geomorphic plausibility was assigned when our evaluation converged with the expression shown in the susceptibility map and vice versa. The results demonstrate that a high geomorphic plausibility was assessed for maps generated using the ALS-based inventory whereas low qualitative maps were produced by using the BGR-inventory. In contrast, holdout validation results revealed that all models exhibit a high quantitative quality. High AUROC values could be observed for maps with apparent low practical usability. Spatial cross-validation was able to detect the spatially differing completeness of the BGR-Inventory (resulting in lower AUROC values). Generally higher (in some cases much higher) AUROC values were observed for models generated with land cover as an explanatory variable. The subsequent geomorphic plausibility check demonstrated that maps generated without land cover exhibit more realistic susceptibility values. Finally, we conclude that the explanatory power of statistical performance measures highly depends on the quality of the inventory used to calculate this statistics. Thus, it is required to additionally assess the geomorphic plausibility of susceptibility maps and not to rely solely on statistical performance measures.

  2. Bio-lubricants derived from waste cooking oil with improved oxidation stability and low-temperature properties.

    PubMed

    Li, Weimin; Wang, Xiaobo

    2015-01-01

    Waste cooking oil (WCO) was chemically modified via epoxidation using H2O2 followed by transesterification with methanol and branched alcohols (isooctanol, isotridecanol and isooctadecanol) to produce bio-lubricants with improved oxidative stability and low temperature properties. Physicochemical properties of synthesized bio-lubricants such as pour point (PP), cloud point (CP), viscosity, viscosity index (VI), oxidative stability, and corrosion resistant property were determined according to standard methods. The synthesized bio-lubricants showed improved low temperature flow performances compared with WCO, which can be attributing to the introduction of branched chains in their molecular structures. What's more, the oxidation stability of the WCO showed more than 10 folds improvement due to the elimination of -C=C-bonds in the WCO molecule. Tribological performances of these bio-lubricants were also investigated using four-ball friction and wear tester. Experimental results showed that derivatives of WCO exhibited favorable physicochemical properties and tribological performances which making them good candidates in formulating eco-friendly lubricants. PMID:25766933

  3. Oxidative stability and ignition quality of algae derived methyl esters containing varying levels of methyl eicosapentaenoate and methyl docosahexaenoate

    NASA Astrophysics Data System (ADS)

    Bucy, Harrison

    Microalgae is currently receiving strong consideration as a potential biofuel feedstock to help meet the advanced biofuels mandate of the 2007 Energy Independence and Security Act because of its theoretically high yield (gallons/acre/year) in comparison to current terrestrial feedstocks. Additionally, microalgae also do not compete with food and can be cultivated with wastewater on non-arable land. Microalgae lipids can be converted into a variety of biofuels including fatty acid methyl esters (e.g. FAME biodiesel), renewable diesel, renewable gasoline, or jet fuel. For microalgae derived FAME, the fuel properties will be directly related to the fatty acid composition of the lipids produced by the given microalgae strain. Several microalgae species under consideration for wide scale cultivation, such as Nannochloropsis, produce lipids with fatty acid compositions containing substantially higher quantities of long chainpolyunsaturated fatty acids (LC-PUFA) in comparison to terrestrial feedstocks. It is expected that increased levels of LC-PUFA will be problematic in terms of meeting all of the current ASTM specifications for biodiesel. For example, it is known that oxidative stability and cetane number decrease with increasing levels of LC-PUFA. However, these same LC-PUFA fatty acids, such as eicosapentaenoic acid (EPA: C20:5) and docosahexaenoic acid (DHA: C22:6) are known to have high nutritional value thereby making separation of these compounds economically attractive. Given the uncertainty in the future value of these LC-PUFA compounds and the economic viability of the separation process, the goal of this study was to examine the oxidative stability and ignition quality of algae-based FAME with varying levels of EPA and DHA removal. Oxidative stability tests were conducted at a temperature of 110°C and airflow of 10 L/h using a Metrohm 743 Rancimat with automatic induction period determination following the EN 14112 Method from the ASTM D6751 and EN 14214

  4. The influence of time dependent flight and maneuver velocities and elastic or viscoelastic flexibilities on aerodynamic and stability derivatives

    NASA Astrophysics Data System (ADS)

    Cochrane, Alexander P.; Merrett, Craig G.; Hilton, Harry H.

    2014-12-01

    The advent of new structural concepts employing composites in primary load carrying aerospace structures in UAVs, MAVs, Boeing 787s, Airbus A380s, etc., necessitates the inclusion of flexibility as well as viscoelasticity in static structural and aero-viscoelastic analyses. Differences and similarities between aeroelasticity and aero-viscoelasticity have been investigated in [2]. An investigation is undertaken as to the dependence and sensitivity of aerodynamic and stability derivatives to elastic and viscoelastic structural flexibility and as to time dependent flight and maneuver velocities. Longitudinal, lateral and directional stabilities are investigated. It has been a well established fact that elastic lifting surfaces are subject to loss of control effectiveness and control reversal at certain flight speeds, which depend on aerodynamic, structural and material properties [5]. Such elastic analyses are extended to linear viscoelastic materials under quasi-static, dynamic, and sudden and gradual loading conditions. In elastic wings one of the critical static parameters is the velocity at which control reversal takes place (VREVE). Since elastic formulations constitute viscoelastic initial conditions, viscoelastic reversal may occur at speeds VREV<≧VREVE, but furthermore does so in time at 0 < tREV ≤ ∞. The influence of the twin effects of viscoelastic and elastic materials and of variable flight velocities on longitudinal, lateral, directional and spin stabilities are also investigated. It has been a well established fact that elastic lifting surfaces are subject to loss of control effectiveness and control reversal at certain flight speeds, which depend on aerodynamic, structural and material properties [5]. Such elastic analyses are here extended to linear viscoelastic materials under quasi-static, dynamic, and sudden and gradual loading conditions. In elastic wings the critical parameter is the velocity at which control reversal takes place (VREVE

  5. The influence of time dependent flight and maneuver velocities and elastic or viscoelastic flexibilities on aerodynamic and stability derivatives

    SciTech Connect

    Cochrane, Alexander P.; Merrett, Craig G.; Hilton, Harry H.

    2014-12-10

    The advent of new structural concepts employing composites in primary load carrying aerospace structures in UAVs, MAVs, Boeing 787s, Airbus A380s, etc., necessitates the inclusion of flexibility as well as viscoelasticity in static structural and aero-viscoelastic analyses. Differences and similarities between aeroelasticity and aero-viscoelasticity have been investigated in [2]. An investigation is undertaken as to the dependence and sensitivity of aerodynamic and stability derivatives to elastic and viscoelastic structural flexibility and as to time dependent flight and maneuver velocities. Longitudinal, lateral and directional stabilities are investigated. It has been a well established fact that elastic lifting surfaces are subject to loss of control effectiveness and control reversal at certain flight speeds, which depend on aerodynamic, structural and material properties [5]. Such elastic analyses are extended to linear viscoelastic materials under quasi-static, dynamic, and sudden and gradual loading conditions. In elastic wings one of the critical static parameters is the velocity at which control reversal takes place (V{sub REV}{sup E}). Since elastic formulations constitute viscoelastic initial conditions, viscoelastic reversal may occur at speeds V{sub REV<}{sup ≧}V{sub REV}{sup E}, but furthermore does so in time at 0 < t{sub REV} ≤ ∞. The influence of the twin effects of viscoelastic and elastic materials and of variable flight velocities on longitudinal, lateral, directional and spin stabilities are also investigated. It has been a well established fact that elastic lifting surfaces are subject to loss of control effectiveness and control reversal at certain flight speeds, which depend on aerodynamic, structural and material properties [5]. Such elastic analyses are here extended to linear viscoelastic materials under quasi-static, dynamic, and sudden and gradual loading conditions. In elastic wings the critical parameter is the velocity at

  6. Foundations of Soil Organic Matter Stabilization: Tracing the Influence of Mineralogy on the Initial Sorption of Root-Derived Carbon

    NASA Astrophysics Data System (ADS)

    Neurath, R.; Nico, P. S.; Pett-Ridge, J.; Firestone, M.

    2014-12-01

    Soils are the largest terrestrial carbon (C) reservoir, storing 2,300 Gt C globally, with the largest C input allocated by plant roots. Many root-derived C inputs are low molecular weight compounds (exudates), although complex C compounds from sloughed off cells and decaying roots also contribute precursors to the soil organic matter (SOM) pool. Root-derived compounds are metabolized by microorganisms, using extracellular enzymes to degrade the more complex C compounds. Thus, products of microbial use of root C may be free in soil solution or occur as microbial cell material. Products of root decomposition are stabilized in soil when C compounds are protected from degradation by (i) chemical recalcitrance, (ii) physical protection by aggregation, or (iii) physical-chemical protection by sorption to mineral surfaces. Previous studies show that sorption of SOM to soil minerals can stabilize C compounds for up to thousands of years. We examined the influence of soil mineralogy on sorption of root-derived C. We hypothesized that differences in specific surface area (SSA) and chemical reactivity of four mineral types: goethite, kaolinite, quartz, as well as native minerals extracted from field soil, are significant controls on the rate, quantity, and composition of mineral-sorbed SOM. Soils were collected at the UC Hopland Research and Extension Center in Hopland, CA and planted in soil microcosms with the common annual grass A. barbata; seeds collected from the field site. Microcosms were incubated in a sealed chamber under 13CO2 (99 atom%) for 8 weeks. Plant photosynthesized-C is allocated to the soil via roots, and with the 13C label, allows us to trace the fate of plant-derived C in the soil. Minerals, which were isolated in 18 μm mesh to exclude roots but not microorganisms, were extracted and measured for total C and 13C atom% after a 12 week growing season of A. barbata. Preliminary FTIR and 13C-NMR analysis show differences in the chemical composition of

  7. Organelle genome stability in anther-derived doubled haploids of wheat (Triticum aestivum L., cv. 'Moisson').

    PubMed

    Rode, A; Hartmann, C; Dron, M; Picard, E; Ouetier, F

    1985-12-01

    Chloroplast and mitochondrial compartments of a parental line of wheat (Triticum aestivum L., cv. 'Moisson') and its anther-derived doubled haploid lines have been analyzed and compared on the basis of their DNA restriction patterns. The results obtained show that no noticeable difference can be detected between doubled haploid lines and parental line at the level of ctDNA and mtDNA organization. It may be concluded that in vitro culture by itself does not systematically generate a cytoplasmic variation in germ cells. PMID:24247401

  8. Stabilization of Satellite derived Gravity Field Coefficients by Earth Rotation Parameters

    NASA Astrophysics Data System (ADS)

    Heiker, A.; Kutterer, H.; Müller, J.

    2009-04-01

    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.

  9. Neural networks, nativism, and the plausibility of constructivism.

    PubMed

    Quartz, S R

    1993-09-01

    Recent interest in PDP (parallel distributed processing) models is due in part to the widely held belief that they challenge many of the assumptions of classical cognitive science. In the domain of language acquisition, for example, there has been much interest in the claim that PDP models might undermine nativism. Related arguments based on PDP learning have also been given against Fodor's anti-constructivist position--a position that has contributed to the widespread dismissal of constructivism. A limitation of many of the claims regarding PDP learning, however, is that the principles underlying this learning have not been rigorously characterized. In this paper, I examine PDP models from within the framework of Valiant's PAC (probably approximately correct) model of learning, now the dominant model in machine learning, and which applies naturally to neural network learning. From this perspective, I evaluate the implications of PDP models for nativism and Fodor's influential anti-constructivist position. In particular, I demonstrate that, contrary to a number of claims, PDP models are nativist in a robust sense. I also demonstrate that PDP models actually serve as a good illustration of Fodor's anti-constructivist position. While these results may at first suggest that neural network models in general are incapable of the sort of concept acquisition that is required to refute Fodor's anti-constructivist position, I suggest that there is an alternative form of neural network learning that demonstrates the plausibility of constructivism. This alternative form of learning is a natural interpretation of the constructivist position in terms of neural network learning, as it employs learning algorithms that incorporate the addition of structure in addition to weight modification schemes. By demonstrating that there is a natural and plausible interpretation of constructivism in terms of neural network learning, the position that nativism is the only plausible model of

  10. Theoretical studies on the stability, detonation performance and possibility of synthesis of the nitro derivatives of epoxyethane.

    PubMed

    Zhang, Xueli; Gong, Xuedong

    2014-08-01

    Compounds with heterocyclic rings and NO2 groups have drawn much attention as high energy density compounds in recent years. In this study, the nitro derivatives 1-4 of epoxyethane (ETO) were investigated, and their synthetic possibilities in thermodynamics and thermal stability were predicted. The trigger bond for 1, 2 and 3 is the C-C bond, but for 4 it is the C-NO2 bond. The bond dissociation energies (EBDs) were estimated to be 205.40-164.86 kJ mol(-1) and h 50s were 53-126 cm. EBD, h 50 and energy gap all decrease from 1 to 4. A linear relationship exists between the strain energy and the number of the NO2 group. Derivative 2 has a zero oxygen balance and possesses the best detonation properties (D=8.77 km s(-1) and P=33.88 GPa) as a single explosive. Derivatives 3 and 4 used as oxidizers in the composite explosives of hexahydro-1,3,5-trinitro-1,3,5-triazine (RDX) produce very good detonation performance (D=9.36 km s(-1), P=40.15 GPa and I s = 281.56 s for 3/RDX, and D=9.45 km s(-1), P=41.04 GPa and I s=280.34 s for 4/RDX). The intermolecular hydrogen bonding and dispersion interactions of 3/RDX and 4/RDX show that the compatibilities of these composites are acceptable. PMID:25092241

  11. Studies on chalcone derivatives: Complex formation, thermal behavior, stability constant and antioxidant activity

    NASA Astrophysics Data System (ADS)

    El-Sayed, Yusif S.; Gaber, M.

    2015-02-01

    The chalcone 3-[4‧-dimethylaminophenyl]-1-(2-pyridyl) prop-2-en-1-one (DMAPP) and 3-(4‧-diethylaminophenyl)-1-(2-pyridinyl) prop-2-en-1-one abbreviated as DEAPP have been synthesized and characterized with IR, 1H NMR, 13C NMR spectroscopic techniques as described previously (El-Daly et al., 2008; Gaber et al., 2009; El-Sayed, 2013). By using UV visible spectroscopy method the mole fraction ratio for copper with DMAPP and DEAPP complexes were determined and it was found to be 1:1. The stability constants of this complex have been determined by Job's method. The stability constant (Kf) of copper with DMAPP and DEAPP complexes in universal buffer pH = 3.2 was determined to be 9.9 × 104 and 5.2 × 104 respectively. The effect of Cu(II) ion on the emission spectrum of the free chalcone is also assigned. Adherence to Beer's law and Ringbom optimum concentration ranges are determined. The thermal decomposition of the metal complexes is studied by TGA technique. The kinetic parameters like activation energy, pre-exponential factor and entropy of activation are estimated. The structure of complexes was energetically optimized through molecular mechanics applying MM+ force field coupled with molecular dynamics simulation. The bond lengths and bond angles have been calculated to confirm the geometry of the ligands and their Cu(II) complexes. The mode of interaction of the chalcone to copper nanoparticles was studied. The apparent association constants of the colloidal copper nanoparticles:chalcone complexes in solution were evaluated using the spectral method and compared with the formation constant of the Cu(II) chalcone complexes. Antioxidant activity of these chalcones was evaluated by using 1,1‧-diphenyl-2-picrylhydrazyl (DPPHrad) radicals scavenging method, which showed that the antioxidant activity of DMAPP has higher value than the DEAPP. Semi-empirical study results showed that DMAPP have higher dipole moment than DEAPP [1].

  12. An ester derivative of the drug gabapentin: pH dependent crystal stability

    NASA Astrophysics Data System (ADS)

    André, Vânia; Marques, M. Matilde; da Piedade, M. F. Minas; Duarte, M. Teresa

    2010-06-01

    Gabapentin solutions with different pHs were prepared and slow crystallization was allowed to occur. Different crystalline forms were obtained at pHs up to 7, whereas alkaline media (pH 9) gave rise to an amorphous product. A new crystal structure of an ethyl ester derivative, obtained at pH 2 under Fischer esterification conditions, is described herein. Esterification blocked the supramolecular interactions typically observed through the carboxyl group of gabapentin, which resulted in a dramatic change in the solid-state structure. As it is known, this change could have a marked influence on the physiological absorption characteristics of the drug, which supports the search for ester-based gabapentin prodrugs as a means of improving the limited bioavailability of the drug.

  13. How Physicists Made Stable Lévy Processes Physically Plausible

    NASA Astrophysics Data System (ADS)

    Schinckus, Christophe

    2013-08-01

    Stable Lévy processes have very interesting properties for describing the complex behaviour of non-equilibrium dissipative systems such as turbulence, anomalous diffusion or financial markets. However, although these processes better fit the empirical data, some of their statistical properties can raise several theoretical problems in empirical applications because they generate infinite variables. Econophysicists have developed statistical solutions to make these processes physically plausible. This paper presents a review of these analytical solutions (truncations) for stable Lévy processes and how econophysicists transformed them into data-driven processes. The evolution of these analytical solutions is presented as a progressive research programme provided by (econo)physicists for theoretical problems encountered in financial economics in the 1960s and the 1970s.

  14. Complex Learning in Bio-plausible Memristive Networks

    PubMed Central

    Deng, Lei; Li, Guoqi; Deng, Ning; Wang, Dong; Zhang, Ziyang; He, Wei; Li, Huanglong; Pei, Jing; Shi, Luping

    2015-01-01

    The emerging memristor-based neuromorphic engineering promises an efficient computing paradigm. However, the lack of both internal dynamics in the previous feedforward memristive networks and efficient learning algorithms in recurrent networks, fundamentally limits the learning ability of existing systems. In this work, we propose a framework to support complex learning functions by introducing dedicated learning algorithms to a bio-plausible recurrent memristive network with internal dynamics. We fabricate iron oxide memristor-based synapses, with well controllable plasticity and a wide dynamic range of excitatory/inhibitory connection weights, to build the network. To adaptively modify the synaptic weights, the comprehensive recursive least-squares (RLS) learning algorithm is introduced. Based on the proposed framework, the learning of various timing patterns and a complex spatiotemporal pattern of human motor is demonstrated. This work paves a new way to explore the brain-inspired complex learning in neuromorphic systems. PMID:26090862

  15. Complex Learning in Bio-plausible Memristive Networks.

    PubMed

    Deng, Lei; Li, Guoqi; Deng, Ning; Wang, Dong; Zhang, Ziyang; He, Wei; Li, Huanglong; Pei, Jing; Shi, Luping

    2015-01-01

    The emerging memristor-based neuromorphic engineering promises an efficient computing paradigm. However, the lack of both internal dynamics in the previous feedforward memristive networks and efficient learning algorithms in recurrent networks, fundamentally limits the learning ability of existing systems. In this work, we propose a framework to support complex learning functions by introducing dedicated learning algorithms to a bio-plausible recurrent memristive network with internal dynamics. We fabricate iron oxide memristor-based synapses, with well controllable plasticity and a wide dynamic range of excitatory/inhibitory connection weights, to build the network. To adaptively modify the synaptic weights, the comprehensive recursive least-squares (RLS) learning algorithm is introduced. Based on the proposed framework, the learning of various timing patterns and a complex spatiotemporal pattern of human motor is demonstrated. This work paves a new way to explore the brain-inspired complex learning in neuromorphic systems. PMID:26090862

  16. On the biological plausibility of Wind Turbine Syndrome.

    PubMed

    Harrison, Robert V

    2015-01-01

    An emerging environmental health issue relates to potential ill-effects of wind turbine noise. There have been numerous suggestions that the low-frequency acoustic components in wind turbine signals can cause symptoms associated with vestibular system disorders, namely vertigo, nausea, and nystagmus. This constellation of symptoms has been labeled as Wind Turbine Syndrome, and has been identified in case studies of individuals living close to wind farms. This review discusses whether it is biologically plausible for the turbine noise to stimulate the vestibular parts of the inner ear and, by extension, cause Wind Turbine Syndrome. We consider the sound levels that can activate the semicircular canals or otolith end organs in normal subjects, as well as in those with preexisting conditions known to lower vestibular threshold to sound stimulation. PMID:25295915

  17. Alkaloids from Pandanus amaryllifolius: Isolation and Their Plausible Biosynthetic Formation.

    PubMed

    Tsai, Yu-Chi; Yu, Meng-Lun; El-Shazly, Mohamed; Beerhues, Ludger; Cheng, Yuan-Bin; Chen, Lei-Chin; Hwang, Tsong-Long; Chen, Hui-Fen; Chung, Yu-Ming; Hou, Ming-Feng; Wu, Yang-Chang; Chang, Fang-Rong

    2015-10-23

    Pandanus amaryllifolius Roxb. (Pandanaceae) is used as a flavor and in folk medicine in Southeast Asia. The ethanolic crude extract of the aerial parts of P. amaryllifolius exhibited antioxidant, antibiofilm, and anti-inflammatory activities in previous studies. In the current investigation, the purification of the ethanolic extract yielded nine new compounds, including N-acetylnorpandamarilactonines A (1) and B (2); pandalizines A (3) and B (4); pandanmenyamine (5); pandamarilactones 2 (6) and 3 (7), and 5(E)-pandamarilactonine-32 (8); and pandalactonine (9). The isolated alkaloids, with either a γ-alkylidene-α,β-unsaturated-γ-lactone or γ-alkylidene-α,β-unsaturated-γ-lactam system, can be classified into five skeletons including norpandamarilactonine, indolizinone, pandanamine, pandamarilactone, and pandamarilactonine. A plausible biosynthetic route toward 1-5, 7, and 9 is proposed. PMID:26461164

  18. Conjugated polyelectrolyte-stabilized silver nanoparticles coupled with pyrene derivative for ultrasensitive fluorescent detection of iodide.

    PubMed

    Xiao, Yi; Zhang, Ye; Huang, Hongmei; Zhang, Youyu; Du, Beilei; Chen, Fang; Zheng, Qiao; He, Xiaoxiao; Wang, Kemin

    2015-01-01

    A new sensing system is developed for selective and ultrasensitive detection of iodide based on the inner filter effect (IFE) between conjugated polyelectrolyte-stabilized silver nanoparticles (P1-AgNPs) and 4-oxo-4-(pyren-1-ylmethoxy) butanoic acid (probe 1). P1-AgNPs are designed to be capable of functioning as a composite light-absorber. Meanwhile, probe 1 is selected as an ideal fluorophore because its emission spectrum can perfectly overlap with the absorption band of P1-AgNPs. The intense fluorescence of probe 1 quenched by P1-AgNPs can be efficiently recovered after adding H2O2 and I(-) via the oxidation-etching and regeneration of P1-AgNPs. Under the optimum conditions, this facile IFE-based approach allows the sensitive and selective determination of I(-) in tap water, iodized salt and urine with the detection limit as low as 0.3 nM (S/N=3). Interestingly, the regenerated AgNPs is in smaller size and well-dispersed perhaps due to the particular role of P1 as a polymer localizer containing pyridinyl and sulfonate groups. PMID:25281159

  19. Operational stabilities of different chemical derivatives of Novozym 435 in an alcoholysis reaction.

    PubMed

    Villalba, María; Verdasco-Martín, Carlos M; Dos Santos, Jose C S; Fernandez-Lafuente, Roberto; Otero, Cristina

    2016-08-01

    Industrial use of Novozym 435 in synthesis of structured lipids and biodiesel via alcoholysis is limited by mass transfer effects of the glycerides through immobilized enzymes and its low operational stability under operation conditions. To better understand this, differently modified Novozym 435 preparations, differing in their surface nature and in their interactions with reactants, have been compared in the alcoholysis of Camelina sativa oil. The three modifications performed have been carried out under conditions where all exposed groups of the enzyme have been modified. These modifications were: 2,4,6-trinitrobenzensulfonic acid (Novo-TNBS), ethylendiamine (Novo-EDA) and polyethylenimine (Novo-PEI). Changes in their operational performance are analyzed in terms of changes detected by scan electron microscopy in the support morphology. The hydrophobic nature of the TNBS accelerates the reaction rate; t-ButOH co-solvent swells the macroporous acrylic particles of Lewatit VP OC 1600 in all biocatalysts, except in the case of Novo-PEI. This co-solvent only increases the maximal conversions obtained at 24h using the modified biocatalysts. t-ButOH reduces enzyme inactivation by alcohol and water. In a co-solvent system, these four biocatalysts remain fully active after 14 consecutive reaction cycles of 24h, but only Novo-TNBS yields maximal conversion before cycle 5. Some deposits on biocatalyst particles could be appreciated during reuses, and TNBS derivatization diminishes the accumulation of product deposits on the catalyst surface. Most particles of commercial Novozym(®) 435 are broken after operation for 14 reaction cycles. The broken particles are fully active, but they cause problems of blockage in filtration operations and column reactors. The three derivatizations studied make the matrix particles more resistant to rupture. PMID:27241290

  20. Oxidative stability of milk influenced by fatty acids, antioxidants, and copper derived from feed.

    PubMed

    Havemose, M S; Weisbjerg, M R; Bredie, W L P; Poulsen, H D; Nielsen, J H

    2006-06-01

    Differences in the oxidative stability of milk from cows fed grass-clover silage or hay were examined in relation to fatty acid composition and contents of antioxidants and copper in the milk. The oxidation processes were induced by exposing the milk to fluorescent light. Protein oxidation was measured as an accumulation of dityrosine, whereas lipid oxidation was measured as an accumulation of lipid hydroperoxides as the primary oxidation product, and as the secondary oxidation products, pentanal, hexanal, and heptanal. No differences were found in the protein oxidation of the 2 types of milk measured as accumulation of dityrosine, but there was an increased accumulation of lipid hydroperoxides and hexanal in milk from cows fed grass-clover silage, compared with milk from cows fed hay. The higher degree of lipid oxidation in milk from cows fed grass-clover silage could not be explained from the concentration of alpha-tocopherol, carotenoids, uric acid, and copper in the milk. However, it was thought to be highly influenced by the significantly higher concentration of linolenic acid present in milk from cows fed grass-clover silage. A larger part of alpha-tocopherol and beta-carotene was transferred from the feed to the milk when cows were fed grass-clover silage than when cows were fed hay as roughage. The significantly higher concentration of polyunsaturated fatty acids in milk from cows fed grass-clover silage may be important for the better transfer of alpha-tocopherol from the feed to the milk. Other circumstances, as the different conditions in the rumen may also play a role, due to the different types of roughages and their digestibility, or be related to the mechanisms during milk production for the higher yielding cows fed grass-clover silage. PMID:16702260

  1. A Selective G-Quadruplex DNA-Stabilizing Ligand Based on a Cyclic Naphthalene Diimide Derivative.

    PubMed

    Islam, Md Monirul; Fujii, Satoshi; Sato, Shinobu; Okauchi, Tatsuo; Takenaka, Shigeori

    2015-01-01

    A cyclic naphthalene diimide (cyclic NDI, 1), carrying a benzene moiety as linker chain, was synthesized and its interaction with G-quadruplex DNAs of a-core and a-coreTT as a human telomeric DNA, c-kit and c-myc as DNA sequence at promoter region, or thrombin-binding aptamer (TBA) studied based on UV-VIS and circular dichroism (CD) spectroscopic techniques, thermal melting temperature measurement, and FRET-melting assay. The circular dichroism spectra showed that 1 induced the formation of different types of G-quadruplex DNA structure. Compound 1 bound to these G-quadruplexes with affinities in the range of 106-107 M-1 order and a 2:1 stoichiometry. Compound 1 showed 270-fold higher selectivity for a-core than dsDNA with a preferable a-core binding than a-coreTT, c-kit, c-myc and TBA in the presence of K+, which is supported by thermal melting studies. The FRET-melting assay also showed that 1 bound preferentially to human telomeric DNA. Compound 1 showed potent inhibition against telomerase activity with an IC50 value of 0.9 μM and preferable binding to G-quadruplexes DNA than our previously published cyclic NDI derivative 3 carrying a benzene moiety as longer linker chain. PMID:26076114

  2. Practical aspects of a maximum likelihood estimation method to extract stability and control derivatives from flight data

    NASA Technical Reports Server (NTRS)

    Iliff, K. W.; Maine, R. E.

    1976-01-01

    A maximum likelihood estimation method was applied to flight data and procedures to facilitate the routine analysis of a large amount of flight data were described. Techniques that can be used to obtain stability and control derivatives from aircraft maneuvers that are less than ideal for this purpose are described. The techniques involve detecting and correcting the effects of dependent or nearly dependent variables, structural vibration, data drift, inadequate instrumentation, and difficulties with the data acquisition system and the mathematical model. The use of uncertainty levels and multiple maneuver analysis also proved to be useful in improving the quality of the estimated coefficients. The procedures used for editing the data and for overall analysis are also discussed.

  3. Effects of flight instrumentation errors on the estimation of aircraft stability and control derivatives. [including Monte Carlo analysis

    NASA Technical Reports Server (NTRS)

    Bryant, W. H.; Hodge, W. F.

    1974-01-01

    An error analysis program based on an output error estimation method was used to evaluate the effects of sensor and instrumentation errors on the estimation of aircraft stability and control derivatives. A Monte Carlo analysis was performed using simulated flight data for a high performance military aircraft, a large commercial transport, and a small general aviation aircraft for typical cruise flight conditions. The effects of varying the input sequence and combinations of the sensor and instrumentation errors were investigated. The results indicate that both the parameter accuracy and the corresponding measurement trajectory fit error can be significantly affected. Of the error sources considered, instrumentation lags and control measurement errors were found to be most significant.

  4. Novel coumarin modified GLP-1 derivatives with enhanced plasma stability and prolonged in vivo glucose-lowering ability

    PubMed Central

    Han, Jing; Sun, Lidan; Huang, Xun; Li, Zheng; Zhang, Chenyu; Qian, Hai; Huang, Wenlong

    2014-01-01

    Background and Purpose The short biological half-life limits the therapeutic use of glucagon-like peptide-1 (GLP-1) and chemical modification to improve the interaction of peptides with serum albumin represents an effective strategy to develop long-acting peptide analogues. Coumarin, a natural product, is known to bind tightly to plasma proteins and possesses many biological activities. Therefore, we designed and synthesized a series of coumarin-modified GLP-1 derivatives, hypothesizing that conjugation with coumarin would retain the therapeutic effects and prolong the biological half-life of the conjugates. Experimental Approach Four cysteine-modified GLP-1 analogues (1–4) were prepared using Gly8-GLP-1(7–36)-NH2 peptide as a starting point. These analogues were conjugated with two coumarin maleimides to yield eight compounds (conjugates 6–13) for testing. Activation of human GLP-1 receptors, stability to enzymic inactivation in plasma and binding to human albumin were assessed in vitro. In vivo, effects on oral glucose tolerance tests (OGTT) in rats and on blood glucose levels in db/db mice were studied. Key Results Most conjugates showed well preserved receptor activation efficacy, enhanced albumin-binding properties and improved in vitro plasma stability and conjugate 7 was selected to undergo further assessment. In rats, conjugate 7 had a longer circulating t1/2 than exendin-4 or liraglutide. A prolonged antidiabetic effect of conjugate 7 was observed after OGTT in rats and a prolonged hypoglycaemic effect in db/db mice. Conclusions and Implications Cysteine-specific coumarin conjugation with GLP-1 offers a useful approach to the development of long-acting incretin-based antidiabetic agents. Conjugate 7 is a promising long-lasting GLP-1 derivative deserving further investigation. PMID:25039358

  5. Brain-derived peptides increase blood-brain barrier GLUT1 glucose transporter gene expression via mRNA stabilization.

    PubMed

    Boado, R J

    1998-10-23

    The present investigation studied the effect of the brain-derived peptide preparation Cerebrolysin (CI, EBEWE, Austria) on the turnover rate and gene expression of the blood-brain barrier (BBB) GLUT1 glucose transporter mRNA. Studies were performed in brain endothelial cultured cells transfected with the human (h) GLUT1 transcript. In control cells, the full length 2.8 Kb hGLUT1 mRNA was rapidly degraded following transfection, and the abundance of this transcript at 4 and 6 h was comparable to background mRNA levels seen in cells transfected without hGLUT1 mRNA. On the contrary, the decay of the hGLUT1 mRNA was stabilized in CI-treated cells resulting in a marked reduction in the fractional turnover rate (72.4 and 4.0%/h, control and CI, respectively). In parallel experiments, CI induced a significant increase in the levels of immunoreactive GLUT1 protein measured by enzyme-linked immunosorbent assay (ELISA). In conclusion, data presented here demonstrate that factors in CI increase BBB-GLUT1 transcript stability, and that this is associated with an induction of BBB-GLUT1 gene expression in brain endothelial cultured cells. PMID:9832194

  6. Determination of the stability and control derivatives of the NASA F/A-18 HARV using flight data

    NASA Technical Reports Server (NTRS)

    Napolitano, Marcello R.; Spagnuolo, Joelle M.

    1993-01-01

    This report documents the research conducted for the NASA-Ames Cooperative Agreement No. NCC 2-759 with West Virginia University. A complete set of the stability and control derivatives for varying angles of attack from 10 deg to 60 deg were estimated from flight data of the NASA F/A-18 HARV. The data were analyzed with the use of the pEst software which implements the output-error method of parameter estimation. Discussions of the aircraft equations of motion, parameter estimation process, design of flight test maneuvers, and formulation of the mathematical model are presented. The added effects of the thrust vectoring and single surface excitation systems are also addressed. The results of the longitudinal and lateral directional derivative estimates at varying angles of attack are presented and compared to results from previous analyses. The results indicate a significant improvement due to the independent control surface deflections induced by the single surface excitation system, and at the same time, a need for additional flight data especially at higher angles of attack.

  7. Impact of Protein Stability, Cellular Localization, and Abundance on Proteomic Detection of Tumor-Derived Proteins in Plasma

    PubMed Central

    Faca, Vitor M.; Zhang, Wenxuan; Zhang, Qing; Jain, Anjali; Hanash, Sam; Agus, David B.; McIntosh, Martin W.; Mallick, Parag

    2011-01-01

    Tumor-derived, circulating proteins are potentially useful as biomarkers for detection of cancer, for monitoring of disease progression, regression and recurrence, and for assessment of therapeutic response. Here we interrogated how a protein's stability, cellular localization, and abundance affect its observability in blood by mass-spectrometry-based proteomics techniques. We performed proteomic profiling on tumors and plasma from two different xenograft mouse models. A statistical analysis of this data revealed protein properties indicative of the detection level in plasma. Though 20% of the proteins identified in plasma were tumor-derived, only 5% of the proteins observed in the tumor tissue were found in plasma. Both intracellular and extracellular tumor proteins were observed in plasma; however, after normalizing for tumor abundance, extracellular proteins were seven times more likely to be detected. Although proteins that were more abundant in the tumor were also more likely to be observed in plasma, the relationship was nonlinear: Doubling the spectral count increased detection rate by only 50%. Many secreted proteins, even those with relatively low spectral count, were observed in plasma, but few low abundance intracellular proteins were observed. Proteins predicted to be stable by dipeptide composition were significantly more likely to be identified in plasma than less stable proteins. The number of tryptic peptides in a protein was not significantly related to the chance of a protein being observed in plasma. Quantitative comparison of large versus small tumors revealed that the abundance of proteins in plasma as measured by spectral count was associated with the tumor size, but the relationship was not one-to-one; a 3-fold decrease in tumor size resulted in a 16-fold decrease in protein abundance in plasma. This study provides quantitative support for a tumor-derived marker prioritization strategy that favors secreted and stable proteins over all but the

  8. Impact of protein stability, cellular localization, and abundance on proteomic detection of tumor-derived proteins in plasma.

    PubMed

    Fang, Qiaojun; Kani, Kian; Faca, Vitor M; Zhang, Wenxuan; Zhang, Qing; Jain, Anjali; Hanash, Sam; Agus, David B; McIntosh, Martin W; Mallick, Parag

    2011-01-01

    Tumor-derived, circulating proteins are potentially useful as biomarkers for detection of cancer, for monitoring of disease progression, regression and recurrence, and for assessment of therapeutic response. Here we interrogated how a protein's stability, cellular localization, and abundance affect its observability in blood by mass-spectrometry-based proteomics techniques. We performed proteomic profiling on tumors and plasma from two different xenograft mouse models. A statistical analysis of this data revealed protein properties indicative of the detection level in plasma. Though 20% of the proteins identified in plasma were tumor-derived, only 5% of the proteins observed in the tumor tissue were found in plasma. Both intracellular and extracellular tumor proteins were observed in plasma; however, after normalizing for tumor abundance, extracellular proteins were seven times more likely to be detected. Although proteins that were more abundant in the tumor were also more likely to be observed in plasma, the relationship was nonlinear: Doubling the spectral count increased detection rate by only 50%. Many secreted proteins, even those with relatively low spectral count, were observed in plasma, but few low abundance intracellular proteins were observed. Proteins predicted to be stable by dipeptide composition were significantly more likely to be identified in plasma than less stable proteins. The number of tryptic peptides in a protein was not significantly related to the chance of a protein being observed in plasma. Quantitative comparison of large versus small tumors revealed that the abundance of proteins in plasma as measured by spectral count was associated with the tumor size, but the relationship was not one-to-one; a 3-fold decrease in tumor size resulted in a 16-fold decrease in protein abundance in plasma. This study provides quantitative support for a tumor-derived marker prioritization strategy that favors secreted and stable proteins over all but the

  9. Adipose-Derived Stem Cells From Diabetic Mice Show Impaired Vascular Stabilization in a Murine Model of Diabetic Retinopathy

    PubMed Central

    Cronk, Stephen M.; Kelly-Goss, Molly R.; Ray, H. Clifton; Mendel, Thomas A.; Hoehn, Kyle L.; Bruce, Anthony C.; Dey, Bijan K.; Guendel, Alexander M.; Tavakol, Daniel N.; Herman, Ira M.; Yates, Paul A.

    2015-01-01

    Diabetic retinopathy is characterized by progressive vascular dropout with subsequent vision loss. We have recently shown that an intravitreal injection of adipose-derived stem cells (ASCs) can stabilize the retinal microvasculature, enabling repair and regeneration of damaged capillary beds in vivo. Because an understanding of ASC status from healthy versus diseased donors will be important as autologous cellular therapies are developed for unmet clinical needs, we took advantage of the hyperglycemic Akimba mouse as a preclinical in vivo model of diabetic retinopathy in an effort aimed at evaluating therapeutic efficacy of adipose-derived stem cells (mASCs) derived either from healthy, nondiabetic or from diabetic mice. To these ends, Akimba mice received intravitreal injections of media conditioned by mASCs or mASCs themselves, subsequent to development of substantial retinal capillary dropout. mASCs from healthy mice were more effective than diabetic mASCs in protecting the diabetic retina from further vascular dropout. Engrafted ASCs were found to preferentially associate with the retinal vasculature. Conditioned medium was unable to recapitulate the vasoprotection seen with injected ASCs. In vitro diabetic ASCs showed decreased proliferation and increased apoptosis compared with healthy mASCs. Diabetic ASCs also secreted less vasoprotective factors than healthy mASCs, as determined by high-throughput enzyme-linked immunosorbent assay. Our findings suggest that diabetic ASCs are functionally impaired compared with healthy ASCs and support the utility of an allogeneic injection of ASCs versus autologous or conditioned media approaches in the treatment of diabetic retinopathy. PMID:25769654

  10. Prebiotically plausible oligoribonucleotide ligation facilitated by chemoselective acetylation

    NASA Astrophysics Data System (ADS)

    Bowler, Frank R.; Chan, Christopher K. W.; Duffy, Colm D.; Gerland, Béatrice; Islam, Saidul; Powner, Matthew W.; Sutherland, John D.; Xu, Jianfeng

    2013-05-01

    The recent synthesis of pyrimidine ribonucleoside-2‧,3‧-cyclic phosphates under prebiotically plausible conditions has strengthened the case for the involvement of ribonucleic acid (RNA) at an early stage in the origin of life. However, a prebiotic conversion of these weakly activated monomers, and their purine counterparts, to the 3‧,5‧-linked RNA polymers of extant biochemistry has been lacking (previous attempts led only to short oligomers with mixed linkages). Here we show that the 2‧-hydroxyl group of oligoribonucleotide-3‧-phosphates can be chemoselectively acetylated in water under prebiotically credible conditions, which allows rapid and efficient template-directed ligation. The 2‧-O-acetyl group at the ligation junction of the product RNA strand can be removed under conditions that leave the internucleotide bonds intact. Remarkably, acetylation of mixed oligomers that possess either 2‧- or 3‧-terminal phosphates is selective for the 2‧-hydroxyl group of the latter. This newly discovered chemistry thus suggests a prebiotic route from ribonucleoside-2‧,3‧-cyclic phosphates to predominantly 3‧,5‧-linked RNA via partially 2‧-O-acetylated RNA.

  11. Plausible inference: A multi-valued logic for problem solving

    NASA Technical Reports Server (NTRS)

    Friedman, L.

    1979-01-01

    A new logic is developed which permits continuously variable strength of belief in the truth of assertions. Four inference rules result, with formal logic as a limiting case. Quantification of belief is defined. Propagation of belief to linked assertions results from dependency-based techniques of truth maintenance so that local consistency is achieved or contradiction discovered in problem solving. Rules for combining, confirming, or disconfirming beliefs are given, and several heuristics are suggested that apply to revising already formed beliefs in the light of new evidence. The strength of belief that results in such revisions based on conflicting evidence are a highly subjective phenomenon. Certain quantification rules appear to reflect an orderliness in the subjectivity. Several examples of reasoning by plausible inference are given, including a legal example and one from robot learning. Propagation of belief takes place in directions forbidden in formal logic and this results in conclusions becoming possible for a given set of assertions that are not reachable by formal logic.

  12. Plausible explanation for the Δ5/2+(2000) puzzle

    NASA Astrophysics Data System (ADS)

    Xie, Ju-Jun; Martínez Torres, A.; Oset, E.; González, P.

    2011-05-01

    From a Faddeev calculation for the π-(Δρ)N5/2-(1675) system we show the plausible existence of three dynamically generated I(JP)=3/2(5/2+) baryon states below 2.3 GeV, whereas only two resonances, Δ5/2+(1905)(****) and Δ5/2+(2000)(**), are cataloged in the Particle Data Book Review. Our results give theoretical support to data analyses extracting two distinctive resonances, Δ5/2+(~1740) and Δ5/2+(~2200), from which the mass of Δ5/2+(2000)(**) is estimated. We propose that these two resonances should be cataloged instead of Δ5/2+(2000). This proposal gets further support from the possible assignment of the other baryon states found in the approach in the I=1/2,3/2 with JP=1/2+,3/2+,5/2+ sectors to known baryonic resonances. In particular, Δ1/2+(1750)(*) is naturally interpreted as a πN1/2-(1650) bound state.

  13. A computer program for calculating symmetrical aerodynamic characteristics and lateral-directional stability derivatives of wing-body combinations with blowing jets

    NASA Technical Reports Server (NTRS)

    Lan, C. E.; Mehrotra, S. C.; Fox, C. H., Jr.

    1978-01-01

    The necessary information for using a computer program to calculate the aerodynamic characteristics under symmetrical flight conditions and the lateral-directional stability derivatives of wing-body combinations with upper-surface-blowing (USB) or over-wing-blowing (OWB) jets are described. The following new features were added to the program: (1) a fuselage of arbitrary body of revolution has been included. The effect of wing-body interference can now be investigated, and (2) all nine lateral-directional stability derivatives can be calculated. The program is written in FORTRAN language and runs on CDC Cyber 175 and Honeywell 66/60 computers.

  14. TECHNICAL BASIS FOR DOE STANDARD 3013 EQUIVALENCY SUPPORTING REDUCED TEMPERATURE STABILIZATION OF OXALATE-DERIVED PLUTONIUM DIOXIDE PRODUCED BY THE HB-LINE FACILITY AT SAVANNAH RIVER SITE

    SciTech Connect

    Duffey, J. M.; Livingston, R. R.; Berg, J. M.; Veirs, D. K.

    2013-02-06

    This report documents the technical basis for determining that stabilizing highpurity PuO{sub 2} derived from oxalate precipitation at the SRS HB-Line facility at a minimum of 625 {degree}C for at least four hours in an oxidizing atmosphere is equivalent to stabilizing at a minimum of 950 {degree}C for at least two hours as regards meeting the objectives of stabilization defined by DOE-STD-3013 if the material is handled in a way to prevent excessive absorption of water.

  15. The mood stabilizers lithium and valproate selectively activate the promoter IV of brain-derived neurotrophic factor in neurons.

    PubMed

    Yasuda, S; Liang, M-H; Marinova, Z; Yahyavi, A; Chuang, D-M

    2009-01-01

    Brain-derived neurotrophic factor (BDNF) has been strongly implicated in the synaptic plasticity, neuronal survival and pathophysiology of depression. Lithium and valproic acid (VPA) are two primary mood-stabilizing drugs used to treat bipolar disorder. Treatment of cultured rat cortical neurons with therapeutic concentrations of LiCl or VPA selectively increased the levels of exon IV (formerly rat exon III)-containing BDNF mRNA, and the activity of BDNF promoter IV. Surprisingly, lithium- or VPA-responsive element(s) in promoter IV resides in a region upstream from the calcium-responsive elements (CaREs) responsible for depolarization-induced BDNF induction. Moreover, activation of BDNF promoter IV by lithium or VPA occurred in cortical neurons depolarized with KCl, and deletion of these three CaREs did not abolish lithium- or VPA-induced activation. Lithium and VPA are direct inhibitors of glycogen synthase kinase-3 (GSK-3) and histone deacetylase (HDAC), respectively. We showed that lithium-induced activation of promoter IV was mimicked by pharmacological inhibition of GSK-3 or short interfering RNA (siRNA)-mediated gene silencing of GSK-3alpha or GSK-3beta isoforms. Furthermore, treatment with other HDAC inhibitors, sodium butyrate and trichostatin A, or transfection with an HDAC1-specific siRNA also activated BDNF promoter IV. Our study demonstrates for the first time that GSK-3 and HDAC are respective initial targets for lithium and VPA to activate BDNF promoter IV, and that this BDNF induction involves a novel responsive region in promoter IV of the BDNF gene. Our results have strong implications for the therapeutic actions of these two mood stabilizers. PMID:17925795

  16. Mutations in the A subunit affect yield, stability, and protease sensitivity of nontoxic derivatives of heat-labile enterotoxin.

    PubMed

    Magagnoli, C; Manetti, R; Fontana, M R; Giannelli, V; Giuliani, M M; Rappuoli, R; Pizza, M

    1996-12-01

    Heat-labile toxin (LT) is a protein related to cholera toxin, produced by enterotoxigenic Escherichia coli strains, that is organized as an AB5 complex. A number of nontoxic derivatives of LT, useful for new or improved vaccines against diarrheal diseases or as mucosal adjuvants, have been constructed by site-directed mutagenesis. Here we have studied the biochemical properties of the nontoxic mutants LT-K7 (Arg-7-->Lys), LT-D53 (Val-53-->Asp), LT-K63 (Ser-63-->Lys), LT-K97 (Val-97-->Lys), LT-K104 (Tyr-104-->Lys), LT-K114 (Ser-114-->Lys), and LT-K7/K97 (Arg-7-->Lys and Val-97-->Lys). We have found that mutations in the A subunit may have profound effects on the ability to form the AB5 structure and on the stability and trypsin sensitivity of the purified proteins. Unstable mutants, during long-term storage at 4 degrees C, showed a decrease in the amount of the assembled protein in solution and a parallel appearance of soluble monomeric B subunit. This finding suggests that the stability of the B pentamer is influenced by the A subunit which is associated with it. Among the seven nontoxic mutants tested, LT-K63 was found to be efficient in AB5 production, extremely stable during storage, resistant to proteolytic attack, and very immunogenic. In conclusion, LT-K63 is a good candidate for the development of antidiarrheal vaccines and mucosal adjuvants. PMID:8945604

  17. From ether to acid: A plausible degradation pathway of glycerol dialkyl glycerol tetraethers

    NASA Astrophysics Data System (ADS)

    Liu, Xiao-Lei; Birgel, Daniel; Elling, Felix J.; Sutton, Paul A.; Lipp, Julius S.; Zhu, Rong; Zhang, Chuanlun; Könneke, Martin; Peckmann, Jörn; Rowland, Steven J.; Summons, Roger E.; Hinrichs, Kai-Uwe

    2016-06-01

    Glycerol dialkyl glycerol tetraethers (GDGTs) are ubiquitous microbial lipids with extensive demonstrated and potential roles as paleoenvironmental proxies. Despite the great attention they receive, comparatively little is known regarding their diagenetic fate. Putative degradation products of GDGTs, identified as hydroxyl and carboxyl derivatives, were detected in lipid extracts of marine sediment, seep carbonate, hot spring sediment and cells of the marine thaumarchaeon Nitrosopumilus maritimus. The distribution of GDGT degradation products in environmental samples suggests that both biotic and abiotic processes act as sinks for GDGTs. More than a hundred newly recognized degradation products afford a view of the stepwise degradation of GDGT via (1) ether bond hydrolysis yielding hydroxyl isoprenoids, namely, GDGTol (glycerol dialkyl glycerol triether alcohol), GMGD (glycerol monobiphytanyl glycerol diether), GDD (glycerol dibiphytanol diether), GMM (glycerol monobiphytanol monoether) and bpdiol (biphytanic diol); (2) oxidation of isoprenoidal alcohols into corresponding carboxyl derivatives and (3) chain shortening to yield C39 and smaller isoprenoids. This plausible GDGT degradation pathway from glycerol ethers to isoprenoidal fatty acids provides the link to commonly detected head-to-head linked long chain isoprenoidal hydrocarbons in petroleum and sediment samples. The problematic C80 to C82 tetraacids that cause naphthenate deposits in some oil production facilities can be generated from H-shaped glycerol monoalkyl glycerol tetraethers (GMGTs) following the same process, as indicated by the distribution of related derivatives in hydrothermally influenced sediments.

  18. A biologically plausible learning rule for the Infomax on recurrent neural networks.

    PubMed

    Hayakawa, Takashi; Kaneko, Takeshi; Aoyagi, Toshio

    2014-01-01

    A fundamental issue in neuroscience is to understand how neuronal circuits in the cerebral cortex play their functional roles through their characteristic firing activity. Several characteristics of spontaneous and sensory-evoked cortical activity have been reproduced by Infomax learning of neural networks in computational studies. There are, however, still few models of the underlying learning mechanisms that allow cortical circuits to maximize information and produce the characteristics of spontaneous and sensory-evoked cortical activity. In the present article, we derive a biologically plausible learning rule for the maximization of information retained through time in dynamics of simple recurrent neural networks. Applying the derived learning rule in a numerical simulation, we reproduce the characteristics of spontaneous and sensory-evoked cortical activity: cell-assembly-like repeats of precise firing sequences, neuronal avalanches, spontaneous replays of learned firing sequences and orientation selectivity observed in the primary visual cortex. We further discuss the similarity between the derived learning rule and the spike timing-dependent plasticity of cortical neurons. PMID:25505404

  19. A biologically plausible learning rule for the Infomax on recurrent neural networks

    PubMed Central

    Hayakawa, Takashi; Kaneko, Takeshi; Aoyagi, Toshio

    2014-01-01

    A fundamental issue in neuroscience is to understand how neuronal circuits in the cerebral cortex play their functional roles through their characteristic firing activity. Several characteristics of spontaneous and sensory-evoked cortical activity have been reproduced by Infomax learning of neural networks in computational studies. There are, however, still few models of the underlying learning mechanisms that allow cortical circuits to maximize information and produce the characteristics of spontaneous and sensory-evoked cortical activity. In the present article, we derive a biologically plausible learning rule for the maximization of information retained through time in dynamics of simple recurrent neural networks. Applying the derived learning rule in a numerical simulation, we reproduce the characteristics of spontaneous and sensory-evoked cortical activity: cell-assembly-like repeats of precise firing sequences, neuronal avalanches, spontaneous replays of learned firing sequences and orientation selectivity observed in the primary visual cortex. We further discuss the similarity between the derived learning rule and the spike timing-dependent plasticity of cortical neurons. PMID:25505404

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

    NASA Technical Reports Server (NTRS)

    Stephenson, J. D.

    1983-01-01

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

  1. A plausible mechanism for auxin patterning along the developing root

    PubMed Central

    2010-01-01

    Background In plant roots, auxin is critical for patterning and morphogenesis. It regulates cell elongation and division, the development and maintenance of root apical meristems, and other processes. In Arabidopsis, auxin distribution along the central root axis has several maxima: in the root tip, in the basal meristem and at the shoot/root junction. The distal maximum in the root tip maintains the stem cell niche. Proximal maxima may trigger lateral or adventitious root initiation. Results We propose a reflected flow mechanism for the formation of the auxin maximum in the root apical meristem. The mechanism is based on auxin's known activation and inhibition of expressed PIN family auxin carriers at low and high auxin levels, respectively. Simulations showed that these regulatory interactions are sufficient for self-organization of the auxin distribution pattern along the central root axis under varying conditions. The mathematical model was extended with rules for discontinuous cell dynamics so that cell divisions were also governed by auxin, and by another morphogen Division Factor which combines the actions of cytokinin and ethylene on cell division in the root. The positional information specified by the gradients of these two morphogens is able to explain root patterning along the central root axis. Conclusion We present here a plausible mechanism for auxin patterning along the developing root, that may provide for self-organization of the distal auxin maximum when the reverse fountain has not yet been formed or has been disrupted. In addition, the proximal maxima are formed under the reflected flow mechanism in response to periods of increasing auxin flow from the growing shoot. These events may predetermine lateral root initiation in a rhyzotactic pattern. Another outcome of the reflected flow mechanism - the predominance of lateral or adventitious roots in different plant species - may be based on the different efficiencies with which auxin inhibits its

  2. Radar-derived asteroid shapes point to a 'zone of stability' for topography slopes and surface erosion rates

    NASA Astrophysics Data System (ADS)

    Richardson, J.; Graves, K.; Bowling, T.

    2014-07-01

    Previous studies of the combined effects of asteroid shape, spin, and self-gravity have focused primarily upon the failure limits for bodies with a variety of standard shapes, friction, and cohesion values [1,2,3]. In this study, we look in the opposite direction and utilize 22 asteroid shape-models derived from radar inversion [4] and 7 small body shape-models derived from spacecraft observations [5] to investigate the region in shape/spin space [1,2] wherein self-gravity and rotation combine to produce a stable minimum state with respect to surface potential differences, dynamic topography, slope magnitudes, and erosion rates. This erosional minimum state is self-correcting, such that changes in the body's rotation rate, either up or down, will increase slope magnitudes across the body, thereby driving up erosion rates non-linearly until the body has once again reached a stable, minimized surface state [5]. We investigated this phenomenon in a systematic fashion using a series of synthesized, increasingly prolate spheroid shape models. Adjusting the rotation rate of each synthetic shape to minimize surface potential differences, dynamic topography, and slope magnitudes results in the magenta curve of the figure (right side), defining the zone of maximum surface stability (MSS). This MSS zone is invariant both with respect to body size (gravitational potential and rotational potential scale together with radius), and density when the scaled-spin of [2] is used. Within our sample of observationally derived small-body shape models, slow rotators (Group A: blue points), that are not in the maximum surface stability (MSS) zone and where gravity dominates the slopes, will generally experience moderate erosion rates (left plot) and will tend to move up and to the right in shape/spin space as the body evolves (right plot). Fast rotators (Group C: red points), that are not in the MSS zone and where spin dominates the slopes, will generally experience high erosion rates

  3. Urey prize lecture: On the diversity of plausible planetary systems

    NASA Technical Reports Server (NTRS)

    Lissauer, J. J.

    1995-01-01

    Models of planet formation and of the orbital stability of planetary systems are used to predict the variety of planetary and satellite systems that may be present within our galaxy. A new approximate global criterion for orbital stability of planetary systems based on an extension of the local resonance overlap criterion is proposed. This criterion implies that at least some of Uranus' small inner moons are significantly less massive than predicted by estimates based on Voyager volumes and densities assumed to equal that of Miranda. Simple calculations (neglecting planetary gravity) suggest that giant planets which acrete substantial amounts of gas while their envelopes are extremely distended ultimately rotate rapidly in the prgrade direction.

  4. Experimental Determination of Effects of Frequency and Amplitude on the Lateral Stability Derivatives for a Delta, a Swept, and Unswept Wing Oscillating in Yaw

    NASA Technical Reports Server (NTRS)

    Fisher, Lewis R

    1958-01-01

    Three wing models were oscillated in yaw about their vertical axes to determine the effects of systematic variations of frequency and amplitude of oscillation on the in-phase and out-of-phase combination lateral stability derivatives resulting from this motion. The tests were made at low speeds for a 60 degree delta wing, a 45 degree swept wing, and an unswept wing; the swept and unswept wings had aspect ratios of 4. The results indicate that large changes in the magnitude of the stability derivatives due to the variation of frequency occur at high angles of attack, particularly for the delta wing. The greatest variations of the derivatives with frequency take place for the lowest frequencies of oscillation; at the higher frequencies, the effects of frequency are smaller and the derivatives become more linear with angle of attack. Effects of amplitude of oscillation on the stability derivatives for delta wings were evident for certain high angles of attack and for the lowest frequencies of oscillation. As the frequency became high, the amplitude effects tended to disappear.

  5. N-Substituted Derivatives of the Azadithiolate Cofactor from the [FeFe] Hydrogenases: Stability and Complexation

    PubMed Central

    Angamuthu, Raja; Chen, Chi-Shian; Cochrane, Tyler R.; Gray, Danielle L.; Schilter, David; Ulloa, Olbelina A.; Rauchfuss, Thomas B.

    2015-01-01

    Experiments are described that probe the stability of N-substituted derivatives of the azadithiolate cofactor recently confirmed in the [FeFe] hydrogenases (Berggren, G., et al. Nature 2013, 499, 66). Acid-catalyzed hydrolysis of bis(thioester) BnN(CH2SAc)2 gives [BnNCH2SCH2]2 rather than azadithiol BnN(CH2SH)2. Treatment of BnN(CH2SAc)2 with NaOtBu generates BnN(CH2SNa)2, which was trapped with NiCl2(diphos) (diphos = 1,2-C2H4(PR2)2; R = Ph (dppe) and Cy (dcpe)) to give fully characterized complexes Ni[(SCH2)2NBn](diphos). The related N-aryl derivative Ni[(SCH2)2NC6H4Cl](diphos) was prepared analogously from 4-ClC6H4N(CH2SAc)2, NaOtBu, and NiCl2(dppe). Crystallographic analysis confirmed that these rare nonbridging [adtR]2− complexes feature distorted square planar Ni centers. The analogue Pd[(SCH2)2NBn](dppe) was also prepared. 31P NMR analysis indicates that Ni[(SCH2)2NBn](dppe) has basicity comparable to typical amines. As shown by cyclic voltammetry, the couple [M[(SCH2)2NBn](dppe)]+/0 is reversible near −2.0 V versus Fc+/0. The wave shifts to −1.78 V upon N-protonation. In the presence of CF3CO2H, Ni[(SCH2)2NBn](dppe) catalyzes hydrogen evolution at rate of 22 s−1 in the acid-independent regime, at room temperature in CH2Cl2 solution. In contrast to the instability of RN(CH2SH)2 (R = alkyl, aryl), the dithiol of tosylamide TsN(CH2SH)2 proved sufficiently stable to allow full characterization. This dithiol reacts with Fe3(CO)12 and, in the presence of base, NiCl2(dppe) to give Fe2[(SCH2)2NTs](CO)6 and Ni[(SCH2)2NTs](dppe), respectively. PMID:26000618

  6. N-Substituted Derivatives of the Azadithiolate Cofactor from the [FeFe] Hydrogenases: Stability and Complexation.

    PubMed

    Angamuthu, Raja; Chen, Chi-Shian; Cochrane, Tyler R; Gray, Danielle L; Schilter, David; Ulloa, Olbelina A; Rauchfuss, Thomas B

    2015-06-15

    Experiments are described that probe the stability of N-substituted derivatives of the azadithiolate cofactor recently confirmed in the [FeFe] hydrogenases (Berggren, G., et al. Nature 2013, 499, 66). Acid-catalyzed hydrolysis of bis(thioester) BnN(CH2SAc)2 gives [BnNCH2SCH2]2 rather than azadithiol BnN(CH2SH)2. Treatment of BnN(CH2SAc)2 with NaO(t)Bu generates BnN(CH2SNa)2, which was trapped with NiCl2(diphos) (diphos = 1,2-C2H4(PR2)2; R = Ph (dppe) and Cy (dcpe)) to give fully characterized complexes Ni[(SCH2)2NBn](diphos). The related N-aryl derivative Ni[(SCH2)2NC6H4Cl](diphos) was prepared analogously from 4-ClC6H4N(CH2SAc)2, NaO(t)Bu, and NiCl2(dppe). Crystallographic analysis confirmed that these rare nonbridging [adt(R)](2-) complexes feature distorted square planar Ni centers. The analogue Pd[(SCH2)2NBn](dppe) was also prepared. (31)P NMR analysis indicates that Ni[(SCH2)2NBn](dppe) has basicity comparable to typical amines. As shown by cyclic voltammetry, the couple [M[(SCH2)2NBn](dppe)](+/0) is reversible near -2.0 V versus Fc(+/0). The wave shifts to -1.78 V upon N-protonation. In the presence of CF3CO2H, Ni[(SCH2)2NBn](dppe) catalyzes hydrogen evolution at rate of 22 s(-1) in the acid-independent regime, at room temperature in CH2Cl2 solution. In contrast to the instability of RN(CH2SH)2 (R = alkyl, aryl), the dithiol of tosylamide TsN(CH2SH)2 proved sufficiently stable to allow full characterization. This dithiol reacts with Fe3(CO)12 and, in the presence of base, NiCl2(dppe) to give Fe2[(SCH2)2NTs](CO)6 and Ni[(SCH2)2NTs](dppe), respectively. PMID:26000618

  7. Preparation, characterization and in vitro evaluation of sterically stabilized liposome containing a naphthalenediimide derivative as anticancer agent.

    PubMed

    Parise, Amelia; Milelli, Andrea; Tumiatti, Vincenzo; Minarini, Anna; Neviani, Paolo; Zuccari, Guendalina

    2015-01-01

    The aim of this study was to incorporate a new naphthalenediimide derivative (AN169) with a promising anticancer activity into pegylated liposomes to an extent that allows its in vitro and in vivo testing without use of toxic solvent. AN169-loaded liposomes were prepared using the thin-film hydration method and characterized for size, polydispersity index, drug content and drug release. We examined their lyophilization ability in the presence of cryoprotectants (trehalose, sucrose and lysine) and the long-term stability of the lyophilized products stored at 4 °C for 3 and 6 months by particle size changes and drug leakage. AN169 was successfully loaded into liposomes with an entrapment efficiency of 87.3 ± 2.5%. The hydrodynamic diameter of these liposomes after sonication was ∼ 145 nm with a high degree of monodispersity. Trehalose was found to be superior to the other lyoprotectants. In particular, trehalose 1:10 lipid:cryoprotectant molar ratio may provide stable lyophilized liposomes with the conservation of physicochemical properties upon freeze-drying and long-term storage conditions. We also assessed their in vitro antitumor activity in human cancer cell lines (HTLA-230 neuroblastoma, Mel 3.0 melanoma, OVCAR-3 ovarian carcinoma and SV620 prostate cancer cells). However, only after 72 h incubation, loaded liposomes showed almost the same IC50 as free AN169. In conclusion, we developed a stable lyophilized liposomal formulation for intravenous administration of AN169 as anticancer drug, with the advantage of avoiding the use of potentially toxic solubilizing agents for future in vivo experiments. PMID:24286206

  8. Making More Plausible What is Hard To Believe: Historical Justifications and Illustrations of Newton's Third Law.

    ERIC Educational Resources Information Center

    Gauld, Colin

    1998-01-01

    Reports that many students do not believe Newton's law of action and reaction and suggests ways in which its plausibility might be enhanced. Reviews how this law has been made more plausible over time by Newton and those who succeeded him. Contains 25 references. (DDR)

  9. Plausibility Reappraisals and Shifts in Middle School Students' Climate Change Conceptions

    ERIC Educational Resources Information Center

    Lombardi, Doug; Sinatra, Gale M.; Nussbaum, E. Michael

    2013-01-01

    Plausibility is a central but under-examined topic in conceptual change research. Climate change is an important socio-scientific topic; however, many view human-induced climate change as implausible. When learning about climate change, students need to make plausibility judgments but they may not be sufficiently critical or reflective. The…

  10. The Influence of pH and Temperature on the Stability of N-[(Piperidine)methylene]daunorubicin Hydrochloride and a Comparison of the Stability of Daunorubicin and Its Four New Amidine Derivatives in Aqueous Solutions

    PubMed Central

    Piekarski, Mikołaj; Dołhań, Agnieszka; Cielecka-Piontek, Judyta; Zalewski, Przemysław; Kycler, Witold; Kaczmarek, Aleksandra; Firlej, Artur; Oszczapowicz, Irena; Jelińska, Anna

    2014-01-01

    The influence of pH and temperature on the stability of N-[(piperidine)methylene]daunorubicin hydrochloride (PPD) was investigated. Degradation was studied using an HPLC method. Specific acid-base catalysis of PPD involves hydrolysis of protonated molecules of PPD catalyzed by hydrogen ions and spontaneous hydrolysis under the influence of water zwitterions, unprotonated molecules, and monoanions of PPD. The thermodynamic parameters of these reactions, energy, enthalpy, and entropy, were calculated. Also, the stability of daunorubicin and its new amidine derivatives (piperidine, morpholine, pyrrolidine, and hexahydroazepin-1-yl) in aqueous solutions was compared and discussed. PMID:24688433

  11. Photoinduced catalytic synthesis of biologically important metabolites from formaldehyde and ammonia under plausible "prebiotic" conditions

    NASA Astrophysics Data System (ADS)

    Delidovich, I. V.; Taran, O. P.; Simonov, A. N.; Matvienko, L. G.; Parmon, V. N.

    2011-08-01

    The article analyzes new and previously reported data on several catalytic and photochemical processes yielding biologically important molecules. UV-irradiation of formaldehyde aqueous solution yields acetaldehyde, glyoxal, glycolaldehyde and glyceraldehyde, which can serve as precursors of more complex biochemically relevant compounds. Photolysis of aqueous solution of acetaldehyde and ammonium nitrate results in formation of alanine and pyruvic acid. Dehydration of glyceraldehyde catalyzed by zeolite HZSM-5-17 yields pyruvaldehyde. Monosaccharides are formed in the course of the phosphate-catalyzed aldol condensation reactions of glycolaldehyde, glyceraldehyde and formaldehyde. The possibility of the direct synthesis of tetroses, keto- and aldo-pentoses from pure formaldehyde due to the combination of the photochemical production of glycolahyde and phosphate-catalyzed carbohydrate chain growth is demonstrated. Erythrulose and 3-pentulose are the main products of such combined synthesis with selectivity up to 10%. Biologically relevant aldotetroses, aldo- and ketopentoses are more resistant to the photochemical destruction owing to the stabilization in hemiacetal cyclic forms. They are formed as products of isomerization of erythrulose and 3-pentulose. The conjugation of the concerned reactions results in a plausible route to the formation of sugars, amino and organic acids from formaldehyde and ammonia under presumed 'prebiotic' conditions.

  12. Binding stability of peptides derived from 1ALA residue and 7GLY residues to sites near active center of fluctuating papain

    NASA Astrophysics Data System (ADS)

    Nishiyama, Katsuhiko

    2012-05-01

    We investigated the binding stability of peptides derived from 1ALA residue and 7GLY residues to sites near active center of fluctuating papain via molecular dynamics and docking simulations. Replacing GLY residue in 8GLY with ALA residue had a positive effect on binding stability to the sites in some cases although the replacing had a negative effect on it in other cases. Furthermore the replacing had a negative effect on the chance of binding to the sites. Residue in peptide should be replaced on the basis of systematic exploration of its position.

  13. A study of the use of experimental stability derivatives in the calculation of the lateral disturbed motions of a swept-wing airplane and comparison with flight results

    NASA Technical Reports Server (NTRS)

    Bird, John D; Jaquet, Byron M

    1951-01-01

    An investigation was made to determine the accuracy with which the lateral flight motions of a swept-wing airplane could be predicted from experimental stability derivatives, determined in the 6-foot-diameter rolling-flow test section and 6 by 6-foot curved-flow test section of the Langley stability tunnel. In addition, determination of the significance of including the nonlinear aerodynamic effects of sideslip in the calculations of the motions was desired. All experimental aerodynamic data necessary for prediction of the lateral flight motions are presented along with a number of comparisons between flight and calculated motions caused by rudder and aileron disturbances.

  14. Effect of Horizontal-Tail Chord on the Calculated Subsonic Span Loads and Stability Derivatives of Isolated Unswept Tail Assemblies in Sideslip and Steady Roll

    NASA Technical Reports Server (NTRS)

    Booth, Katherine W.

    1959-01-01

    Subsonic span loads and the resulting stability derivatives have been calculated using the discrete-horseshoe-vortex method for a systematic series of horizontal tails in combination with a vertical tail of aspect ratio 1.0 in order to provide information on the effect of varying the chord of the horizontal tail for isolated tail assemblies performing sideslip and steady-roll motions. In addition, the effects of horizontal-tail dihedral angle for the sideslip case were obtained. Each tail surface considered had a taper ratio of 0.5 and an unswept quarter-chord line. The investigation covered variations in horizontal-tail chord, horizontal-tail span, and vertical location of the horizontal tail. The span loads and the resulting total stability derivatives as well as the vertical- and horizontal-tail contributions to these tail-assembly derivatives are presented in the figures for the purpose of showing the influence of the geometric variables. The results of this investigation showed trends that were in agreement with the results of previous investigations for variations in horizontal-tail span and vertical location of the horizontal tail. Variations in horizontal-tail chord expressed herein in terms of the root-chord ratio, that is, the ratio of horizontal-tail root chord to vertical-tail root chord, were found to have a pronounced influence on most of the span loads and the resulting stability derivatives. For most of the cases considered, the rate of change of the span load coefficients and the stability derivatives with the root-chord ratio was found to be a maximum for small values of root-chord ratio and to decrease as root-chord ratio increased.

  15. Flight-determined aerodynamic stability and control derivatives of the M2-F2 lifting body vehicle at subsonic speeds

    NASA Technical Reports Server (NTRS)

    Kempel, R. W.; Thompson, R. C.

    1971-01-01

    Aerodynamic derivatives were obtained for the M2-F2 lifting body flight vehicle in the subsonic flight region between Mach numbers of 0.41 and 0.64 and altitudes of 7000 feet to 45,000 feet. The derivatives were determined by a flight time history curve-fitting process utilizing a hybrid computer. The flight-determined derivatives are compared with wind-tunnel and predicted values. Modal-response characteristics, calculated from the flight derivatives, are presented.

  16. Wind-tunnel investigation to determine the low speed yawing stability derivatives of a twin jet fighter model at high angles of attack

    NASA Technical Reports Server (NTRS)

    Coe, P. L., Jr.; Newsom, W. A., Jr.

    1974-01-01

    An investigation was conducted to determine the low-speed yawing stability derivatives of a twin-jet fighter airplane model at high angles of attack. Tests were performed in a low-speed tunnel utilizing variable-curvature walls to simulate pure yawing motion. The results of the study showed that at angles of attack below the stall the yawing derivatives were essentially independent of the yawing velocity and sideslip angle. However, at angles of attack above the stall some nonlinear variations were present and the derivatives were strongly dependent upon sideslip angle. The results also showed that the rolling moment due to yawing was primarily due to the wing-fuselage combination, and that at angles of attack below the stall both the vertical and horizontal tails produced significant contributions to the damping in yaw. Additionally, the tests showed that the use of the forced-oscillation data to represent the yawing stability derivatives is questionable, at high angles of attack, due to large effects arising from the acceleration in sideslip derivatives.

  17. Curved-flow, rolling-flow, and oscillatory pure-yawing wind-tunnel test methods for determination of dynamic stability derivatives

    NASA Technical Reports Server (NTRS)

    Chambers, J. R.; Grafton, S. B.; Lutze, F. H.

    1981-01-01

    The test capabilities of the Stability Wind Tunnel of the Virginia Polytechnic Institute and State University are described, and calibrations for curved and rolling flow techniques are given. Oscillatory snaking tests to determine pure yawing derivatives are considered. Representative aerodynamic data obtained for a current fighter configuration using the curved and rolling flow techniques are presented. The application of dynamic derivatives obtained in such tests to the analysis of airplane motions in general, and to high angle of attack flight conditions in particular, is discussed.

  18. Comparisons of Predictions of the XB-70-1 Longitudinal Stability and Control Derivatives with Flight Results for Six Flight Conditions

    NASA Technical Reports Server (NTRS)

    Wolowicz, C. H.; Yancey, R. B.

    1973-01-01

    Preliminary correlations of flight-determined and predicted stability and control characteristics of the XB-70-1 reported in NASA TN D-4578 were subject to uncertainties in several areas which necessitated a review of prediction techniques particularly for the longitudinal characteristics. Reevaluation and updating of the original predictions, including aeroelastic corrections, for six specific flight-test conditions resulted in improved correlations of static pitch stability with flight data. The original predictions for the pitch-damping derivative, on the other hand, showed better correlation with flight data than the updated predictions. It appears that additional study is required in the application of aeroelastic corrections to rigid model wind-tunnel data and the theoretical determination of dynamic derivatives for this class of aircraft.

  19. Can readers ignore implausibility? Evidence for nonstrategic monitoring of event-based plausibility in language comprehension.

    PubMed

    Isberner, Maj-Britt; Richter, Tobias

    2013-01-01

    We present evidence for a nonstrategic monitoring of event-based plausibility during language comprehension by showing that readers cannot ignore the implausibility of information even if it is detrimental to the task at hand. In two experiments using a Stroop-like paradigm, participants were required to provide positive and negative responses independent of plausibility in an orthographical task (Experiment 1) or a nonlinguistic color judgment task (Experiment 2) to target words that were either plausible or implausible in their context. We expected a nonstrategic assessment of plausibility to interfere with positive responses to implausible words. ANOVAs and linear mixed models analyses of the response latencies revealed a significant interaction of plausibility and required response that supported this prediction in both experiments, despite the use of two very different tasks. Moreover, it could be shown that the effect was not driven by the differential predictability of plausible and implausible words. These results suggest that plausibility monitoring is an inherent component of information processing. PMID:23165201

  20. Determination of the stability and control derivatives of the F/A-18 HARV from flight data using the maximum likelihood method

    NASA Technical Reports Server (NTRS)

    Napolitano, Marcello R.; Spagnuolo, Joelle M.

    1992-01-01

    The research being conducted pertains to the determination of the stability and control derivatives of the F/A-18 High Alpha Research Vehicle (HARV) from flight data using the Maximum Likelihood Method. The document outlines the approach used in the parameter estimation (PID) process and briefly describes the mathematical modeling of the F/A-18 HARV and the maneuvers designed to generate a sufficient data base for the PID research.

  1. Get real: Effects of repeated simulation and emotion on the perceived plausibility of future experiences

    PubMed Central

    Szpunar, Karl K.; Schacter, Daniel L.

    2012-01-01

    People frequently imagine specific interpersonal experiences that might occur in their futures. The present study used a novel experimental paradigm to examine the influence of repeated simulation of future interpersonal experiences on subjective assessments of plausibility for positive, negative, and neutral events. The results demonstrate that repeated simulation increases estimates of plausibility for emotional, but not neutral, future interpersonal experiences. Additional correlational analyses reveal that increases in plausibility for emotional events are associated with concurrent increases in ease of simulation, event detail, and arousal. Implications for daily life and affective disorders such as depression and anxiety are noted. PMID:22686637

  2. The Utility of Cognitive Plausibility in Language Acquisition Modeling: Evidence From Word Segmentation.

    PubMed

    Phillips, Lawrence; Pearl, Lisa

    2015-11-01

    The informativity of a computational model of language acquisition is directly related to how closely it approximates the actual acquisition task, sometimes referred to as the model's cognitive plausibility. We suggest that though every computational model necessarily idealizes the modeled task, an informative language acquisition model can aim to be cognitively plausible in multiple ways. We discuss these cognitive plausibility checkpoints generally and then apply them to a case study in word segmentation, investigating a promising Bayesian segmentation strategy. We incorporate cognitive plausibility by using an age-appropriate unit of perceptual representation, evaluating the model output in terms of its utility, and incorporating cognitive constraints into the inference process. Our more cognitively plausible model shows a beneficial effect of cognitive constraints on segmentation performance. One interpretation of this effect is as a synergy between the naive theories of language structure that infants may have and the cognitive constraints that limit the fidelity of their inference processes, where less accurate inference approximations are better when the underlying assumptions about how words are generated are less accurate. More generally, these results highlight the utility of incorporating cognitive plausibility more fully into computational models of language acquisition. PMID:25656757

  3. High-internal-phase emulsions stabilized by metal-organic frameworks and derivation of ultralight metal-organic aerogels

    NASA Astrophysics Data System (ADS)

    Zhang, Bingxing; Zhang, Jianling; Liu, Chengcheng; Peng, Li; Sang, Xinxin; Han, Buxing; Ma, Xue; Luo, Tian; Tan, Xiuniang; Yang, Guanying

    2016-02-01

    To design high-internal-phase emulsion (HIPE) systems is of great interest from the viewpoints of both fundamental researches and practical applications. Here we demonstrate for the first time the utilization of metal-organic framework (MOF) for HIPE formation. By stirring the mixture of water, oil and MOF at room temperature, the HIPE stabilized by the assembly of MOF nanocrystals at oil-water interface could be formed. The MOF-stabilized HIPE provides a novel route to produce highly porous metal-organic aerogel (MOA) monolith. After removing the liquids from the MOF-stabilized HIPE, the ultralight MOA with density as low as 0.01 g·cm-3 was obtained. The HIPE approach for MOA formation has unique advantages and is versatile in producing different kinds of ultralight MOAs with tunable porosities and structures.

  4. High-internal-phase emulsions stabilized by metal-organic frameworks and derivation of ultralight metal-organic aerogels

    PubMed Central

    Zhang, Bingxing; Zhang, Jianling; Liu, Chengcheng; Peng, Li; Sang, Xinxin; Han, Buxing; Ma, Xue; Luo, Tian; Tan, Xiuniang; Yang, Guanying

    2016-01-01

    To design high-internal-phase emulsion (HIPE) systems is of great interest from the viewpoints of both fundamental researches and practical applications. Here we demonstrate for the first time the utilization of metal-organic framework (MOF) for HIPE formation. By stirring the mixture of water, oil and MOF at room temperature, the HIPE stabilized by the assembly of MOF nanocrystals at oil-water interface could be formed. The MOF-stabilized HIPE provides a novel route to produce highly porous metal-organic aerogel (MOA) monolith. After removing the liquids from the MOF-stabilized HIPE, the ultralight MOA with density as low as 0.01 g·cm−3 was obtained. The HIPE approach for MOA formation has unique advantages and is versatile in producing different kinds of ultralight MOAs with tunable porosities and structures. PMID:26892258

  5. High-internal-phase emulsions stabilized by metal-organic frameworks and derivation of ultralight metal-organic aerogels.

    PubMed

    Zhang, Bingxing; Zhang, Jianling; Liu, Chengcheng; Peng, Li; Sang, Xinxin; Han, Buxing; Ma, Xue; Luo, Tian; Tan, Xiuniang; Yang, Guanying

    2016-01-01

    To design high-internal-phase emulsion (HIPE) systems is of great interest from the viewpoints of both fundamental researches and practical applications. Here we demonstrate for the first time the utilization of metal-organic framework (MOF) for HIPE formation. By stirring the mixture of water, oil and MOF at room temperature, the HIPE stabilized by the assembly of MOF nanocrystals at oil-water interface could be formed. The MOF-stabilized HIPE provides a novel route to produce highly porous metal-organic aerogel (MOA) monolith. After removing the liquids from the MOF-stabilized HIPE, the ultralight MOA with density as low as 0.01 g·cm(-3) was obtained. The HIPE approach for MOA formation has unique advantages and is versatile in producing different kinds of ultralight MOAs with tunable porosities and structures. PMID:26892258

  6. Linear stability of the tearing mode with two-fluid and curvature effects in tokamaks

    SciTech Connect

    Meshcheriakov, Dmytro; Maget, Patrick; Garbet, Xavier; Luetjens, Hinrich; Beyer, Peter

    2012-09-15

    Curvature and diamagnetic effects are both recognized to have a stabilizing influence on tearing modes in the linear regime. In this paper, we investigate the impact of these effects on the linear stability of a (2, 1) magnetic island using non-linear two-fluid MHD simulations and we apply our results to Tore Supra experiments where its stability is not well understood from the single fluid MHD model. Simulations show an initial increase of the linear growth rate and then its reduction until full stability as diamagnetic frequency increases. This mechanism is therefore a plausible explanation for experimental observations where the (2, 1) mode was not observed although the single fluid model predicted its growth. Our simulations also show the importance of curvature for an efficient stabilization. A simple analytical model is derived to support the numerical results.

  7. Stability and maturity of biowaste composts derived by small municipalities: Correlation among physical, chemical and biological indices.

    PubMed

    Oviedo-Ocaña, E R; Torres-Lozada, P; Marmolejo-Rebellon, L F; Hoyos, L V; Gonzales, S; Barrena, R; Komilis, D; Sanchez, A

    2015-10-01

    Stability and maturity are important criteria to guarantee the quality of a compost that is applied to agriculture or used as amendment in degraded soils. Although different techniques exist to evaluate stability and maturity, the application of laboratory tests in municipalities in developing countries can be limited due to cost and application complexities. In the composting facilities of such places, some classical low cost on-site tests to monitor the composting process are usually implemented; however, such tests do not necessarily clearly identify conditions of stability and maturity. In this article, we have applied and compared results of stability and maturity tests that can be easily employed on site (i.e. temperature, pH, moisture, electrical conductivity [EC], odor and color), and of tests that require more complex laboratory techniques (volatile solids, C/N ratio, self-heating, respirometric index, germination index [GI]). The evaluation of the above was performed in the field scale using 2 piles of biowaste applied compost. The monitoring period was from day 70 to day 190 of the process. Results showed that the low-cost tests traditionally employed to monitor the composting process on-site, such as temperature, color and moisture, do not provide consistent determinations with the more complex laboratory tests used to assess stability (e.g. respiration index, self-heating, volatile solids). In the case of maturity tests (GI, pH, EC), both the on-site tests (pH, EC) and the laboratory test (GI) provided consistent results. Although, stability was indicated for most of the samples, the maturity tests indicated that products were consistently immature. Thus, a stable product is not necessarily mature. Conclusively, the decision on the quality of the compost in the installations located in developing countries requires the simultaneous use of a combination of tests that are performed both in the laboratory and on-site. PMID:26216503

  8. Flight-Determined, Subsonic, Lateral-Directional Stability and Control Derivatives of the Thrust-Vectoring F-18 High Angle of Attack Research Vehicle (HARV), and Comparisons to the Basic F-18 and Predicted Derivatives

    NASA Technical Reports Server (NTRS)

    Iliff, Kenneth W.; Wang, Kon-Sheng Charles

    1999-01-01

    The subsonic, lateral-directional, stability and control derivatives of the thrust-vectoring F-1 8 High Angle of Attack Research Vehicle (HARV) are extracted from flight data using a maximum likelihood parameter identification technique. State noise is accounted for in the identification formulation and is used to model the uncommanded forcing functions caused by unsteady aerodynamics. Preprogrammed maneuvers provided independent control surface inputs, eliminating problems of identifiability related to correlations between the aircraft controls and states. The HARV derivatives are plotted as functions of angles of attack between 10deg and 70deg and compared to flight estimates from the basic F-18 aircraft and to predictions from ground and wind tunnel tests. Unlike maneuvers of the basic F-18 aircraft, the HARV maneuvers were very precise and repeatable, resulting in tightly clustered estimates with small uncertainty levels. Significant differences were found between flight and prediction; however, some of these differences may be attributed to differences in the range of sideslip or input amplitude over which a given derivative was evaluated, and to differences between the HARV external configuration and that of the basic F-18 aircraft, upon which most of the prediction was based. Some HARV derivative fairings have been adjusted using basic F-18 derivatives (with low uncertainties) to help account for differences in variable ranges and the lack of HARV maneuvers at certain angles of attack.

  9. Using critical evaluation to reappraise plausibility judgments: A critical cognitive component of conceptual change

    NASA Astrophysics Data System (ADS)

    Lombardi, D.

    2011-12-01

    Plausibility judgments-although well represented in conceptual change theories (see, for example, Chi, 2005; diSessa, 1993; Dole & Sinatra, 1998; Posner et al., 1982)-have received little empirical attention until our recent work investigating teachers' and students' understanding of and perceptions about human-induced climate change (Lombardi & Sinatra, 2010, 2011). In our first study with undergraduate students, we found that greater plausibility perceptions of human-induced climate accounted for significantly greater understanding of weather and climate distinctions after instruction, even after accounting for students' prior knowledge (Lombardi & Sinatra, 2010). In a follow-up study with inservice science and preservice elementary teachers, we showed that anger about the topic of climate change and teaching about climate change was significantly related to implausible perceptions about human-induced climate change (Lombardi & Sinatra, 2011). Results from our recent studies helped to inform our development of a model of the role of plausibility judgments in conceptual change situations. The model applies to situations involving cognitive dissonance, where background knowledge conflicts with an incoming message. In such situations, we define plausibility as a judgment on the relative potential truthfulness of incoming information compared to one's existing mental representations (Rescher, 1976). Students may not consciously think when making plausibility judgments, expending only minimal mental effort in what is referred to as an automatic cognitive process (Stanovich, 2009). However, well-designed instruction could facilitate students' reappraisal of plausibility judgments in more effortful and conscious cognitive processing. Critical evaluation specifically may be one effective method to promote plausibility reappraisal in a classroom setting (Lombardi & Sinatra, in progress). In science education, critical evaluation involves the analysis of how evidentiary

  10. Plausible antioxidant biomechanics and anticonvulsant pharmacological activity of brain-targeted β-carotene nanoparticles

    PubMed Central

    Yusuf, Mohammad; Khan, Riaz A; Khan, Maria; Ahmed, Bahar

    2012-01-01

    increased in P-80-BCNP to 231.0 ± 16.30 seconds, as compared to PTZ (120.10 ± 4.50 seconds) and placebo control (120.30 ± 7.4 seconds). The results of this study demonstrate a plausible novel anticonvulsant activity of β-carotene at a low dose of 2 mg/kg, with brain-targeted nanodelivery, thus increasing its bioavailability and stability. PMID:22915852

  11. Properties of cationic monosubstituted tetraalkylammonium cyclodextrin derivatives – their stability, complexation ability in solution or when deposited on solid anionic surface

    PubMed Central

    Popr, Martin; Filippov, Sergey K; Matushkin, Nikolai; Dian, Juraj

    2015-01-01

    Summary The thermal stability of the monosubstituted cationic cyclodextrin (CD) derivatives PEMEDA-β-CD and PEMPDA-β-CD, which differ in their substituent linker length (ethylene and propylene, respectively), was studied via 1H NMR experiments. PEMPDA-β-CD exhibited higher resistance towards the Hofmann degradation and was chosen as a more suitable host molecule for further studies. Inclusion properties of PEMPDA-β-CD in solution with a series of simple aromatic guests (salicylic acid, p-methoxyphenol and p-nitroaniline) were determined by isothermal titration calorimetry (ITC) and compared to the native β-CD. Permanently charged cationic CD derivatives were successfully deposited on the anionic solid surface of polymeric Nafion® 117 membrane via electrostatic interactions. Deposition kinetics and coverage of the surface were determined by ELSD. Finally, the ability of the CD derivatives bound to the solid surface to encapsulate aromatic compounds from aqueous solution was measured by UV–vis spectroscopy. The obtained results are promising for future industrial applications of the monosubstituted β-CD derivatives, because the preparation of cationic CD derivatives is applicable in large scale, without the need of chromatographic purification. Their ionic deposition on a solid surface is simple, yet robust and a straightforward process as well. PMID:25815069

  12. N-substituted phenothiazine derivatives: how the stability of the neutral and radical cation forms affects overcharge performance in lithium-ion batteries.

    PubMed

    Narayana, Kishore Anand; Casselman, Matthew D; Elliott, Corrine F; Ergun, Selin; Parkin, Sean R; Risko, Chad; Odom, Susan A

    2015-04-27

    Phenothiazine and five N-substituted derivatives were evaluated as electrolyte additives for overcharge protection in LiFePO4 /synthetic graphite lithium-ion batteries. We report on the stability and reactivity of both the neutral and radical-cation forms of these six compounds. While three of the compounds show extensive overcharge protection, the remaining three last for only one to a few cycles. UV/Vis studies of redox shuttle stability in the radical cation form are consistent with the overcharge performance: redox shuttles with spectra that show little change over time exhibit extensive overcharge performance, whereas those with changing spectra have limited overcharge protection. In one case, we determined that a C-N bond cleaves upon oxidation, forming the phenothiazine radical cation and leading to premature overcharge protection failure; in another case, poor solubility appears to limit protection. PMID:25504135

  13. The Stability of Rankings Derived from Composite Indicators: Analysis of the "IL Sole 24 Ore" Quality of Life Report

    ERIC Educational Resources Information Center

    Lun, G.; Holzer, D.; Tappeiner, G.; Tappeiner, U.

    2006-01-01

    The calculation of composite indicators and the derivation of respective rankings is a common method used to benchmark countries or regions. However, although the statistical robustness of these rankings is often criticised, they often still spark off heated political debate. Here, we assess the sensitivity of the province ranking published by the…

  14. Comparative Molecular Field Analysis of fenoterol derivatives interacting with an agonist-stabilized form of the β2-adrenergic receptor

    PubMed Central

    Plazinska, Anita; Pajak, Karolina; Rutkowska, Ewelina; Jimenez, Lucita; Kozocas, Joseph; Koolpe, Gary; Tanga, Mary; Toll, Lawrence; Wainer, Irving W.; Jozwiak, Krzysztof

    2014-01-01

    The β2-adrenergic receptor (β2-AR) agonist [3H]-(R,R′)-methoxyfenoterol was employed as the marker ligand in displacement studies measuring the binding affinities (Ki values) of the stereoisomers of a series of 4′-methoxyfenoterol analogs in which the length of the alkyl substituent at α′ position was varied from 0 to 3 carbon atoms. The binding affinities of the compounds were additionally determined using the inverse agonist [3H]-CGP-12177 as the marker ligand and the ability of the compounds to stimulate cAMP accumulation, measured as EC50 values, were determined in HEK293 cells expressing the β2-AR. The data indicate that the highest binding affinities and functional activities were produced by methyl and ethyl substituents at the α′ position. The results also indicate that the Ki values obtained using [3H]-(R,R′)-methoxyfenoterol as the marker ligand modeled the EC50 values obtained from cAMP stimulation better than the data obtained using [3H]-CGP-12177 as the marker ligand. The data from this study was combined with data from previous studies and processed using the Comparative Molecular Field Analysis approach to produce a CoMFA model reflecting the binding to the β2-AR conformation probed by [3H]-(R,R′)-4′-methoxyfenoterol. The CoMFA model of the agonist-stabilized β2-AR suggests that the binding of the fenoterol analogs to an agonist-stabilized conformation of the β2-AR is governed to a greater extend by steric effects than binding to the [3H]-CGP-12177-stabilized conformation(s) in which electrostatic interactions play a more predominate role. PMID:24326276

  15. Visual saliency: a biologically plausible contourlet-like frequency domain approach

    PubMed Central

    Bian, Peng

    2010-01-01

    In this paper we propose a fast frequency domain saliency detection method that is also biologically plausible, referred to as frequency domain divisive normalization (FDN). We show that the initial feature extraction stage, common to all spatial domain approaches, can be simplified to a Fourier transform with a contourlet-like grouping of coefficients, and saliency detection can be achieved in frequency domain. Specifically, we show that divisive normalization, a model of cortical surround inhibition, can be conducted in frequency domain. Since Fourier coefficients are global in space, we extend to this model by conducting piecewise FDN (PFDN) using overlapping local patches to provide better biological plausibility. Not only do FDN and PFDN outperform current state-of-the-art methods in eye fixation prediction, they are also faster. Speed and simplicity are advantages of our frequency domain approach, and its biological plausibility is the main contribution of our paper. PMID:21886671

  16. Prediction of overall in vitro microsomal stability of drug candidates based on molecular modeling and support vector machines. Case study of novel arylpiperazines derivatives.

    PubMed

    Ulenberg, Szymon; Belka, Mariusz; Król, Marek; Herold, Franciszek; Hewelt-Belka, Weronika; Kot-Wasik, Agata; Bączek, Tomasz

    2015-01-01

    Other than efficacy of interaction with the molecular target, metabolic stability is the primary factor responsible for the failure or success of a compound in the drug development pipeline. The ideal drug candidate should be stable enough to reach its therapeutic site of action. Despite many recent excellent achievements in the field of computational methods supporting drug metabolism studies, a well-recognized procedure to model and predict metabolic stability quantitatively is still lacking. This study proposes a workflow for developing quantitative metabolic stability-structure relationships, taking a set of 30 arylpiperazine derivatives as an example. The metabolic stability of the compounds was assessed in in vitro incubations in the presence of human liver microsomes and NADPH and subsequently quantified by liquid chromatography-mass spectrometry (LC-MS). Density functional theory (DFT) calculations were used to obtain 30 models of the molecules, and Dragon software served as a source of structure-based molecular descriptors. For modeling structure-metabolic stability relationships, Support Vector Machines (SVM), a non-linear machine learning technique, were found to be more effective than a regression technique, based on the validation parameters obtained. Moreover, for the first time, general sites of metabolism for arylpiperazines bearing the 4-aryl-2H-pyrido[1,2-c]pyrimidine-1,3-dione system were defined by analysis of Q-TOF-MS/MS spectra. The results indicated that the application of one of the most advanced chemometric techniques combined with a simple and quick in vitro procedure and LC-MS analysis provides a novel and valuable tool for predicting metabolic half-life values. Given the reduced time and simplicity of analysis, together with the accuracy of the predictions obtained, this is a valid approach for predicting metabolic stability using structural data. The approach presented provides a novel, comprehensive and reliable tool for investigating

  17. Region of stability derived by center of mass acceleration better identifies individuals with difficulty in sit-to-stand movement.

    PubMed

    Fujimoto, Masahiro; Chou, Li-Shan

    2014-04-01

    Poor performance of sit-to-stand (STS) has been identified as one of the predictors of fall risk among elderly adults. This study examined differences in the whole body center of mass (COM) kinematic variables in relation to the regions of stability between elderly adults with difficulty in STS and healthy individuals. Whole body motion data while performing STS were collected from 10 young, 10 elderly and 10 elderly subjects with difficulty in STS. Young subjects were also asked to stand up with their trunk purposely bent forward. The regions of stability were defined with COM position at seat-off and its instantaneous velocity (ROSv) or peak acceleration (ROSa), using a single-link-plus-foot inverted pendulum model. Peak COM accelerations prior to seat-off differed significantly among groups; however, no significant differences were detected in its velocities at seat-off. The ROSa demonstrated a better ability to discriminate elderly adults with difficulty from healthy individuals. Although a similar COM momentum was observed at seat-off, how the momentum was controlled differed between healthy individuals and individuals with difficulty in STS. ROSa could provide insight into how the COM momentum is controlled prior to seat-off, which could be used to differentiate individuals with functional limitations from healthy individuals. PMID:24259008

  18. Physicochemical properties of peanut oil-based diacylglycerol and their derived oil-in-water emulsions stabilized by sodium caseinate.

    PubMed

    Long, Zhao; Zhao, Mouming; Liu, Ning; Liu, Daolin; Sun-Waterhouse, Dongxiao; Zhao, Qiangzhong

    2015-10-01

    High purity peanut oil-based diacylglycerol (PO-DAG) (94.95 wt%) was prepared via enzymatic glycerolysis from peanut oil (PO). The resulting dominance of DAGs was proven to greatly influence the properties of corresponding fresh or frozen-thawed emulsions. Stable fresh oil-in-water emulsions were produced using either PO-DAG or PO, with stability enhanced by increased concentrations of Na-CN. The lower equilibrium interfacial tension along with greater negative ζ-potential of PO revealed that Na-CN was preferentially adsorbed to the PO interface. Adding 0.05 mol/L NaCl to the PO emulsions minimized depletion flocculation caused by the unadsorbed Na-CN, but further NaCl addition increased oil droplet size and concomitant coalescence. For the PO-DAG emulsions, adding 0.2 mol/L NaCl did not significantly (p>0.05) affect their ζ-potential but adding 0.05 or 0.1 mol/L NaCl lowered ζ-potential, although NaCl at these concentrations increased oil droplet size and coalescence. Freezing-thawing process considerably weakened the stability of PO-DAG emulsions. PMID:25872432

  19. Flight-Determined Subsonic Longitudinal Stability and Control Derivatives of the F-18 High Angle of Attack Research Vehicle (HARV) with Thrust Vectoring

    NASA Technical Reports Server (NTRS)

    Iliff, Kenneth W.; Wang, Kon-Sheng Charles

    1997-01-01

    The subsonic longitudinal stability and control derivatives of the F-18 High Angle of Attack Research Vehicle (HARV) are extracted from dynamic flight data using a maximum likelihood parameter identification technique. The technique uses the linearized aircraft equations of motion in their continuous/discrete form and accounts for state and measurement noise as well as thrust-vectoring effects. State noise is used to model the uncommanded forcing function caused by unsteady aerodynamics over the aircraft, particularly at high angles of attack. Thrust vectoring was implemented using electrohydraulically-actuated nozzle postexit vanes and a specialized research flight control system. During maneuvers, a control system feature provided independent aerodynamic control surface inputs and independent thrust-vectoring vane inputs, thereby eliminating correlations between the aircraft states and controls. Substantial variations in control excitation and dynamic response were exhibited for maneuvers conducted at different angles of attack. Opposing vane interactions caused most thrust-vectoring inputs to experience some exhaust plume interference and thus reduced effectiveness. The estimated stability and control derivatives are plotted, and a discussion relates them to predicted values and maneuver quality.

  20. Formation and stabilization of the telomeric antiparallel G-quadruplex and inhibition of telomerase by novel benzothioxanthene derivatives with anti-tumor activity

    NASA Astrophysics Data System (ADS)

    Zhang, Wen; Chen, Min; Ling Wu, Yan; Tanaka, Yoshimasa; Juan Ji, Yan; Lin Zhang, Su; He Wei, Chuan; Xu, Yan

    2015-09-01

    G-quadruplexes formed in telomeric DNA sequences at human chromosome ends can be a novel target for the development of therapeutics for the treatment of cancer patients. Herein, we examined the ability of six novel benzothioxanthene derivatives S1-S6 to induce the formation of and stabilize an antiparallel G-quadruplex by EMSA, UV-melting and CD techniques and the influence of S1-S6 on A549 and SGC7901 cells through real-time cell analysis, wound healing, trap assay methods. Results show that six compounds could differentially induce 26 nt G-rich oligonucleotides to form the G-quadruplex with high selectivity vs C-rich DNA, mutated DNA and double-stranded DNA, stabilize it with high affinity, promote apoptosis and inhibit mobility and telomerase activity of A549 cells and SGC7901 cells. Especially, S1, S3, S4 displayed stronger abilities, of which S3 was the most optimal with the maximum ΔTm value being up to 29.8 °C for G-quadruplex, the minimum IC50 value being 0.53 μM and the maximum cell inhibitory rate being up to 97.2%. This study suggests that this type of compounds that induce the formation of and stabilize the telomeric antiparallel G-quadruplex, and consequently inhibit telomerase activity, leading to cell apoptosis, can be screened for the discovery of novel antitumor therapeutics.

  1. The Influence of Arginine on the Response of Enamel Matrix Derivative (EMD) Proteins to Thermal Stress: Towards Improving the Stability of EMD-Based Products.

    PubMed

    Apicella, Alessandra; Heunemann, Peggy; Bolisetty, Sreenath; Marascio, Matteo; Gemperli Graf, Anja; Garamszegi, Laszlo; Mezzenga, Raffaele; Fischer, Peter; Plummer, Christopher J; Månson, Jan-Anders

    2015-01-01

    In a current procedure for periodontal tissue regeneration, enamel matrix derivative (EMD), which is the active component, is mixed with a propylene glycol alginate (PGA) gel carrier and applied directly to the periodontal defect. Exposure of EMD to physiological conditions then causes it to precipitate. However, environmental changes during manufacture and storage may result in modifications to the conformation of the EMD proteins, and eventually premature phase separation of the gel and a loss in therapeutic effectiveness. The present work relates to efforts to improve the stability of EMD-based formulations such as Emdogain™ through the incorporation of arginine, a well-known protein stabilizer, but one that to our knowledge has not so far been considered for this purpose. Representative EMD-buffer solutions with and without arginine were analyzed by 3D-dynamic light scattering, UV-Vis spectroscopy, transmission electron microscopy and Fourier transform infrared spectroscopy at different acidic pH and temperatures, T, in order to simulate the effect of pH variations and thermal stress during manufacture and storage. The results provided evidence that arginine may indeed stabilize EMD against irreversible aggregation with respect to variations in pH and T under these conditions. Moreover, stopped-flow transmittance measurements indicated arginine addition not to suppress precipitation of EMD from either the buffers or the PGA gel carrier when the pH was raised to 7, a fundamental requirement for dental applications. PMID:26670810

  2. The Influence of Arginine on the Response of Enamel Matrix Derivative (EMD) Proteins to Thermal Stress: Towards Improving the Stability of EMD-Based Products

    PubMed Central

    Bolisetty, Sreenath; Marascio, Matteo; Gemperli Graf, Anja; Garamszegi, Laszlo; Mezzenga, Raffaele; Fischer, Peter; Månson, Jan-Anders

    2015-01-01

    In a current procedure for periodontal tissue regeneration, enamel matrix derivative (EMD), which is the active component, is mixed with a propylene glycol alginate (PGA) gel carrier and applied directly to the periodontal defect. Exposure of EMD to physiological conditions then causes it to precipitate. However, environmental changes during manufacture and storage may result in modifications to the conformation of the EMD proteins, and eventually premature phase separation of the gel and a loss in therapeutic effectiveness. The present work relates to efforts to improve the stability of EMD-based formulations such as Emdogain™ through the incorporation of arginine, a well-known protein stabilizer, but one that to our knowledge has not so far been considered for this purpose. Representative EMD-buffer solutions with and without arginine were analyzed by 3D-dynamic light scattering, UV-Vis spectroscopy, transmission electron microscopy and Fourier transform infrared spectroscopy at different acidic pH and temperatures, T, in order to simulate the effect of pH variations and thermal stress during manufacture and storage. The results provided evidence that arginine may indeed stabilize EMD against irreversible aggregation with respect to variations in pH and T under these conditions. Moreover, stopped-flow transmittance measurements indicated arginine addition not to suppress precipitation of EMD from either the buffers or the PGA gel carrier when the pH was raised to 7, a fundamental requirement for dental applications. PMID:26670810

  3. Formation and stabilization of the telomeric antiparallel G-quadruplex and inhibition of telomerase by novel benzothioxanthene derivatives with anti-tumor activity.

    PubMed

    Zhang, Wen; Chen, Min; Ling Wu, Yan; Tanaka, Yoshimasa; Juan Ji, Yan; Lin Zhang, Su; He Wei, Chuan; Xu, Yan

    2015-01-01

    G-quadruplexes formed in telomeric DNA sequences at human chromosome ends can be a novel target for the development of therapeutics for the treatment of cancer patients. Herein, we examined the ability of six novel benzothioxanthene derivatives S1-S6 to induce the formation of and stabilize an antiparallel G-quadruplex by EMSA, UV-melting and CD techniques and the influence of S1-S6 on A549 and SGC7901 cells through real-time cell analysis, wound healing, trap assay methods. Results show that six compounds could differentially induce 26 nt G-rich oligonucleotides to form the G-quadruplex with high selectivity vs C-rich DNA, mutated DNA and double-stranded DNA, stabilize it with high affinity, promote apoptosis and inhibit mobility and telomerase activity of A549 cells and SGC7901 cells. Especially, S1, S3, S4 displayed stronger abilities, of which S3 was the most optimal with the maximum ΔTm value being up to 29.8 °C for G-quadruplex, the minimum IC50 value being 0.53 μM and the maximum cell inhibitory rate being up to 97.2%. This study suggests that this type of compounds that induce the formation of and stabilize the telomeric antiparallel G-quadruplex, and consequently inhibit telomerase activity, leading to cell apoptosis, can be screened for the discovery of novel antitumor therapeutics. PMID:26329134

  4. Formation and stabilization of the telomeric antiparallel G-quadruplex and inhibition of telomerase by novel benzothioxanthene derivatives with anti-tumor activity

    PubMed Central

    Zhang, Wen; Chen, Min; Ling Wu, Yan; Tanaka, Yoshimasa; Juan Ji, Yan; Lin Zhang, Su; He Wei, Chuan; Xu, Yan

    2015-01-01

    G-quadruplexes formed in telomeric DNA sequences at human chromosome ends can be a novel target for the development of therapeutics for the treatment of cancer patients. Herein, we examined the ability of six novel benzothioxanthene derivatives S1–S6 to induce the formation of and stabilize an antiparallel G-quadruplex by EMSA, UV-melting and CD techniques and the influence of S1–S6 on A549 and SGC7901 cells through real-time cell analysis, wound healing, trap assay methods. Results show that six compounds could differentially induce 26 nt G-rich oligonucleotides to form the G-quadruplex with high selectivity vs C-rich DNA, mutated DNA and double-stranded DNA, stabilize it with high affinity, promote apoptosis and inhibit mobility and telomerase activity of A549 cells and SGC7901 cells. Especially, S1, S3, S4 displayed stronger abilities, of which S3 was the most optimal with the maximum ΔTm value being up to 29.8 °C for G-quadruplex, the minimum IC50 value being 0.53 μM and the maximum cell inhibitory rate being up to 97.2%. This study suggests that this type of compounds that induce the formation of and stabilize the telomeric antiparallel G-quadruplex, and consequently inhibit telomerase activity, leading to cell apoptosis, can be screened for the discovery of novel antitumor therapeutics. PMID:26329134

  5. Transfection of BmCPV genomic dsRNA in silkmoth-derived Bm5 cells: stability and interactions with the core RNAi machinery.

    PubMed

    Swevers, Luc; Kolliopoulou, Anna; Li, Zheng; Daskalaki, Maria; Verret, Frederic; Kalantidis, Kriton; Smagghe, Guy; Sun, Jingchen

    2014-05-01

    While several studies have been conducted to investigate the stability of dsRNA in the extracellular medium (hemolymph, gut content, saliva), little is known regarding the persistence of dsRNA once it has been introduced into the cell. Here, we investigate the stability of Bombyx mori cytoplasmic polyhedrosis virus (BmCPV) genomic dsRNA fragments after transfection into Bombyx-derived Bm5 cells. Using RT-PCR as a detection method, we found that dsRNA could persist for long periods (up to 8 days) in the intracellular environment. While the BmCPV genomic dsRNA was processed by the RNAi machinery, its presence had no effects on other RNAi processes, such as the silencing of a luciferase reporter by dsLuc. We also found that transfection of BmCPV genomic dsRNA could not establish a viral infection in the Bm5 cells, even when co-transfections were carried out with dsRNAs targeting Dicer and Argonaute genes, suggesting that the neutralization by RNAi does not play a role in the establishment of an in vitro culture system. The mechanism of the dsRNA stability in Bm5 cells is discussed, as well as the implications for the establishment for an in vitro culture system for BmCPV. PMID:24636911

  6. Stability, nutrient availability and hydrophobicity of biochars derived from manure, crop residues, and municipal solid waste for their use as soil amendments.

    PubMed

    Zornoza, R; Moreno-Barriga, F; Acosta, J A; Muñoz, M A; Faz, A

    2016-02-01

    We aimed to study the influence of feedstock properties, pyrolysis temperature and holding time on stability, nutrient contents and hydrophobicity of biochars derived from pig manure, crop residues and municipal solid waste. Biochars were prepared at 300 °C, 400 °C, 500 °C and 700 °C for 1 h, 2 h, 4 h and 5 h. All properties were influenced by feedstock except for pH and hydrophobicity. Temperature influenced all properties, whereas no effect of holding time was observed except for hydrophobicity and thermal stability. Increasing temperature increased aromatization and stability. Low temperatures provided higher cation exchange capacity and available nutrients, and lower salinity and alkalinity. Precipitation of phosphates and carbonates occurred with charring, explaining the decrease of available nutrients. Biochars produced at 300 °C showed high hydrophobity, which disappeared over 500 °C owing to the loss of labile aliphatic compounds. The high pH and carbonates contents at >500 °C resulted in suitable biochars for soil liming and decreasing soil metals availability. PMID:26347934

  7. Stabilization dynamics of root versus needle-derived 13C and 15N during 10 years in a temperate forest soil.

    NASA Astrophysics Data System (ADS)

    Bird, J. A.; Hatton, P. J.; Castanha, C.; Torn, M. S.

    2012-12-01

    Belowground plant carbon (C) allocation as fine roots can result in greater retention of C in soils compared with aboveground litter in temperate forest ecosystems. However, much of our understanding of the fate of fine root C and nitrogen (N) in soils comes from short-term studies, often lasting only a few months to a few years. In 2011, we concluded a 10-year field study that compared the fate of dual-labeled (13C/15N) Ponderosa pine fine roots (<2 mm diameter) with needles in a temperate forest soil of the Sierra Nevada, CA, USA. The 13C- and 15N-labeled fine roots or needles were added to mesocosms at two soil depths (top of O or A horizon) to compare C and N stabilization in mineral versus organic soil horizons. We will present data on retention of litter C and N in soil after 0.5, 1.5, 5 and 10 years in situ. For soil samples recovered after 5 years, litter-derived C and N recovered in the mineral soil was partitioned into several operationally-defined physical and chemical soil organic matter (SOM) fractions, which were also characterized by natural abundance 14C. In addition, we compared two fractionation methods (i.e., with and without occluded light fraction isolation) on the partitioning of litter-derived C and N in mineral soil. After 5 years in situ the retention of fine root C in soil (59.9±3.8%) was significantly greater than that of added needle C (38.4±2.0%); however the depth of litter placement in the soil did not affect total litter C or N recovery. Our results provide a direct, decade-scale measure of stabilization of above- and belowground plant inputs to soil, including a portrait of the dominant stabilization mechanisms.

  8. Characteristics and Stability of Empirically Derived Anorexia Nervosa Subtypes: Towards the Identification of Homogeneous Low-Weight Eating Disorder Phenotypes

    PubMed Central

    Wildes, Jennifer E.; Forbush, Kelsie T.; Markon, Kristian E.

    2013-01-01

    Anorexia nervosa (AN) is characterized by within-group heterogeneity in symptom presentation, which poses problems for research on etiology and treatment. This study sought to identify homogeneous subtypes of AN, and examine their short-term stability, using empirical methods. A treatment-seeking sample with AN (N = 194) was assessed at baseline and six- and 12-month follow-ups. Latent class analysis was used to identify homogeneous AN subgroups, and latent transition analysis was used to examine the stability of latent classes. Three low-weight eating disorder classes were identified: 1) fat-phobic restricting (AN-R-FP); 2) fat-phobic binge-eating/purging (AN-BP-FP); and 3) non-fat-phobic restricting (AN-R-NFP). Subtype membership was stable over follow-up, with .68 to .88 probabilities of remaining in the same class from baseline to six months, and .87 to 1.00 from six months to 12 months. The most common transition pattern was between AN-R-FP and AN-R-NFP (56.8% of transitions); the majority of these participants transitioned from AN-R-FP to AN-R-NFP (n = 20/21). Predictors of latent class membership included lifetime mood and substance use disorder comorbidities, negative temperament, illness duration, and body mass index at treatment presentation. Disinhibition (vs. constraint), history of overweight or obesity, and illness duration decreased the probability of latent transition. Findings support the presence of three low-weight eating disorder phenotypes that are highly stable over short-term follow-up. Identification of a stable non-fat-phobic AN phenotype is intriguing, and highlights the importance of studying mechanisms that differentiate fat-phobic and non-fat-phobic eating disorders. PMID:24364605

  9. A mesoscale gravity-wave event observed during CCOPE. IV - Stability analysis and Doppler-derived wave vertical structure

    NASA Technical Reports Server (NTRS)

    Koch, Steven E.; Einaudi, F.; Dorian, Paul B.; Lang, Stephen; Heymsfield, Gerald M.

    1993-01-01

    A summary of the results of a detailed study of the vertical structure of mesoscale gravity waves conducted during the Cooperative Convective Precipitation Experiment (CCOPE) is presented. Pressure perturbation fields derived from the Doppler wind fields are compared with the vertical structure of eigenfunctions resulting from a solution to the Taylor-Goldstein linear wave equation for an atmosphere whose mean state is described by vertical profiles obtained from a representative CCOPE sounding. An analysis of the potential for shear instability is also performed on all of the soundings taken on this day to assess the representativeness of the one chosen for the linear theoretical analysis.

  10. Native and Non-Native Processing of English "Wh-"Questions: Parsing Strategies and Plausibility Constraints.

    ERIC Educational Resources Information Center

    Williams, John N.; Mobius, Peter; Kim, Choonkyong

    2001-01-01

    Investigated processing of English wh-questions by native speakers of English and advanced Chinese, German, and Korean learners of English as a Second Language. Performance was evaluated in relation to parsing strategies and sensitivity to plausibility constraints. Results suggest native and nonnative speakers employ similar strategies in…

  11. Causality vs. Plausibility: Alternative Stances for Inquiry into Human Behavior. Draft.

    ERIC Educational Resources Information Center

    Guba, Egon G.; Lincoln, Yvonna S.

    Arguing that the concept of causality in human experience is archaic, unnecessary, and misleading, particularly in the social/behavioral sciences, a new plausibility approach is proposed for understanding relationships among entities. The epistemological history of causality includes positivist, deductive-nomological, essentialist, activity or…

  12. Preview Effects of Plausibility and Character Order in Reading Chinese Transposed Words: Evidence from Eye Movements

    ERIC Educational Resources Information Center

    Yang, Jinmian

    2013-01-01

    The current paper examined the role of plausibility information in the parafovea for Chinese readers by using two-character transposed words (in which the order of the component characters is reversed but are still words). In two eye-tracking experiments, readers received a preview of a target word that was (1) identical to the target word, (2) a…

  13. The Plausibility of Spiritual Intelligence: Spiritual Experience, Problem Solving and Neural Sites

    ERIC Educational Resources Information Center

    Hyde, Brendan

    2004-01-01

    Australian teachers in Church related schools have begun to use the term "spiritual intelligence" in their educational discourse. Is it accurate to describe spirituality as a form of intelligence? This paper explores whether the notion of spiritual intelligence is plausible. It addresses this firstly by discussing the notion of spiritual…

  14. The Utility of Cognitive Plausibility in Language Acquisition Modeling: Evidence from Word Segmentation

    ERIC Educational Resources Information Center

    Phillips, Lawrence; Pearl, Lisa

    2015-01-01

    The informativity of a computational model of language acquisition is directly related to how closely it approximates the actual acquisition task, sometimes referred to as the model's "cognitive plausibility." We suggest that though every computational model necessarily idealizes the modeled task, an informative language acquisition…

  15. Get Real: Effects of Repeated Simulation and Emotion on the Perceived Plausibility of Future Experiences

    ERIC Educational Resources Information Center

    Szpunar, Karl K.; Schacter, Daniel L.

    2013-01-01

    People frequently imagine specific interpersonal experiences that might occur in their futures. The present study used a novel experimental paradigm to examine the influence of repeated simulation of future interpersonal experiences on subjective assessments of plausibility for positive, negative, and neutral events. The results demonstrate that…

  16. The Collision of Plausibility with Reality: Lifting the Veil of the Ethical Neutrality of Technology

    ERIC Educational Resources Information Center

    Borgmann, Albert

    2012-01-01

    Technology, thought of as the ensemble of utilities and devices and of their impact on our lives, proceeds in steps, each of which seems plausible. This kind of development also encourages the view that technology is value-neutral. It always can be used both for good and ill, and we decide how to use it. The production of food and the development…

  17. Plausibility check of a redesigned rain-on-snow simulator (RASA)

    NASA Astrophysics Data System (ADS)

    Rössler, Ole; Probst, Sabine; Weingartner, Rolf

    2016-04-01

    Rain-on-snow events are fascinating but still not completely understood processes. Although, several studies and equations have been published since decades that describe past events and theoretical descriptions, empirical data of what is happening in the snow cover is far less available. A way to fill this gap of empirical data, rain-on-snow-simulators might be of help. In 2013, Juras et al. published their inspiring idea of a portable rain-on-snow simulator. The huge advantage of this devise - in contrast to other purely field-based experiments - are their fixed, and mostly standardized conditions and the possibility to measure all required data to monitor the water fluxes and melting processes at a time. Mounted in a convenient location, a large number of experiments are relatively easy conductible. We applied and further developed the original device and plausified the results of this redesigned version, called RASA. The principal design was borrowed from the original version being a frame with a sprinkler on top and a snow sample in a box at the bottom, from which the outflow is measured with a tipping gauge. We added a moving sprinkling plate to ensure a uniform distribution of raindrops on the snow, and - most importantly - we suspended the watered snow sampled on weighting cells. The latter enables to continuous measurement of the snow sample throughout the experiment and thus the indirect quantification of liquid water saturation, water holding capacity, and snowmelt amount via balance equations. As it is remains unclear if this device is capable to reproduce known processes, a hypothesis based plausibility check was accomplished. Thus, eight hypothesizes were derived from literature and tested in 28 experiments with the RASA mounted at 2000 m elevation. In general, we were able to reproduce most of the hypotheses. The RASA proved to be a very valuable device that can generate suitable results and has the potential to extend the empirical-experimental data

  18. Students' conceptions about climate change: Using critical evaluation to influence plausibility reappraisals and knowledge reconstruction

    NASA Astrophysics Data System (ADS)

    Lombardi, Douglas Adler

    The Intergovernmental Panel on Climate Change (2007) reported a greater than 90% chance that human activities are responsible for global temperature increases over the last 50 years, as well as other climatic changes. The scientific report also states that alternative explanations (e.g., increasing energy received from the Sun) are less plausible than human-induced climate change. These climate scientists have made their plausibility judgment---which I define as the relative potential truthfulness of alternative explanations---based on the evaluation and coordination of multiple lines evidence with competing theoretical perspectives. Climate change is a highly relevant and gravely serious topic; in an educational setting, climate change also presents an opportunity for students to learn about fundamental scientific principles and how scientists construct knowledge. However, students may be neither naturally evaluative when learning about controversial topics, such as climate change, nor reflective while engaging in judgments about knowledge and knowing (King & Kitchener, 2004), such as plausibility judgments. The purpose of this study was to examine how plausibility judgments and knowledge about human-induced climate change transform during instruction that promotes critical evaluation abilities. An instructional scaffold---called a model evidence link (MEL) diagram---was used in this study. The MEL allowed students to weigh the strength of connections between two alternative models of climate change (i.e., the scientifically accepted model of human-induced climate change and a popular skeptics' model that climate change is caused by increases in the Sun's energy). The results revealed that treatment group participants who used the MEL diagram experienced a significant shift in their plausibility judgments toward the scientifically accepted model. This shift was accompanied by significantly greater postinstructional knowledge of human-induced climate change, with

  19. A Novel Phytase Derived from an Acidic Peat-Soil Microbiome Showing High Stability under Acidic Plus Pepsin Conditions.

    PubMed

    Tan, Hao; Wu, Xiang; Xie, Liyuan; Huang, Zhongqian; Peng, Weihong; Gan, Bingcheng

    2016-01-01

    Four novel phytases of the histidine acid phosphatase family were identified in two publicly available metagenomic datasets of an acidic peat-soil microbiome in northeastern Bavaria, Germany. These enzymes have low similarity to all the reported phytases. They were overexpressed in Escherichia coli and purified. Catalytic efficacy in simulated gastric fluid was measured and compared among the four candidates. The phytase named rPhyPt4 was selected for its high activity. It is the first phytase identified from unculturable Acidobacteria. The phytase showed a longer half-life than all the gastric-stable phytases that have been reported to date, suggesting a strong resistance to low pH and pepsin. A wide pH profile was observed between pH 1.5 and 5.0. At the optimum pH (2.5) the activity was 2,790 μmol/min/mg at the physiological temperature of 37°C and 3,989 μmol/min/mg at the optimum temperature of 60°C. Due to the competent activity level as well as the high gastric stability, the phytase could be a potential candidate for practical use in livestock and poultry feeding. PMID:27336313

  20. Effect of polyethylene glycol conjugation on the circulatory stability of plasma-derived human butyrylcholinesterase in mice.

    PubMed

    Sun, Wei; Luo, Chunyuan; Tipparaju, Prasanthi; Doctor, Bhupendra P; Saxena, Ashima

    2013-03-25

    Exogenously administered human serum butyrylcholinesterase (Hu BChE) was demonstrated to function as a bioscavenger of highly toxic organophosphorus (OP) compounds in several animal species. Since the enzyme is isolated from human serum, it is currently the most suitable pretreatment for human use. A dose of 200-300 mg/70 kg human adult is projected to provide protection from 2 X LD(50) of soman. Due to the limited supply of Hu BChE, strategies aimed at reducing the dose of enzyme are being explored. In this study, we investigated the effect of modification with polyethylene glycol (PEG) on the in vivo stability of Hu BChE. Mice were given two injections of either Hu BChE or Hu BChE modified with PEG-5K or PEG-20K, six weeks apart. Pharmacokinetic parameters, such as mean residence time (MRT), maximal concentration (C(max)), elimination half-life (T(1/2)), and area under the plasma concentration time curve extrapolated to infinity (AUC), were determined. For the first injection, values for MRT, T(1/2), Cmax, and AUC for PEG-5K-Hu BChE and PEG-20K-Hu BChE were similar to those for Hu BChE. These values for the second injection of Hu BChE as well as PEG-Hu BChEs were lower as compared to those for the first injections, likely due to antibody-mediated clearance. PMID:23220586

  1. Bioactivity of a Rice Bran-Derived Peptide and its Sensory Evaluation and Storage Stability in Orange Juice.

    PubMed

    Graves, Amanda M; Hettiarachchy, Navam; Rayaprolu, Srinivas; Li, Ruiqi; Horax, Ronny; Seo, Han-Seok

    2016-04-01

    A pentapeptide prepared from rice bran demonstrated growth inhibition on human lung, liver, breast, and colon cancer cell lines. The objectives of this study were to evaluate the human prostate cancer growth inhibition by the pentapeptide and its 6-mo storage stability by incorporating spray-dried orange juice, and determining sensory acceptability. The pentapeptide showed inhibition of human prostate cancer cells by 45% at 460 μg/mL concentration. When incorporated in spray-dried orange juice, and reconstituted with water and tested, there was an approximately 10% degradation of the peptide at 620 μg/mL concentration under refrigerated conditions over a 6 mo storage period, whereas at ambient temperature the degradation was 30%. Larger degradation was observed when 240 or 460 μg/mL pentapeptide was used. Overall, consumer panelists liked sensory aspect of the reconstituted pentapeptide incorporated orange juice beverage. Also consumer panelists liked the color and mouthfeel attributes, their hedonic impression of flavor attribute was slightly low due to unpalatable bitter note caused by the presence of the peptide. Incorporation of the pentapeptide in spray-dried orange juice has the potential to serve as a functional food ingredient that can offer health benefits to consumers. It is possible that the structural instability can be minimized by encapsulation. PMID:26894442

  2. Convenient Preparation and Detailed Analysis of a Series of NHC-Stabilized Phosphorus(I) Dyes and Their Derivatives.

    PubMed

    Macdonald, Charles L B; Binder, Justin F; Swidan, Ala'aeddeen; Nguyen, Jennifer H; Kosnik, Stephanie C; Ellis, Bobby D

    2016-07-18

    A safe, convenient, and P-atom-efficient synthesis of N-heterocyclic-carbene- (NHC-) stabilized phosphorus(I) bromide salts is reported that involves P(+) transfer from an easily prepared triphosphenium precursor. The resulting family of phosphamethine cyanine dyes featuring N,N'-dialkyl-substituted 4,5-dimethylimidazole-2-ylidenes ((R)NHC(Me)) and benzimidazole-2-ylidenes ((R)NHC(B)) (R = Me, Et, iPr) have been fully characterized. We found that increasing N-alkyl group size causes increased twisting of the carbene fragments from the C-P-C plane, which decreases the magnitude of hyperconjugation between the π-type lone pair on phosphorus and the carbene fragments. This decrease is manifested as changes in the (31)P NMR chemical shifts, magnitudes of the P-C coupling constants, and electronic spectra of the cations. The reactivities of these ions toward various oxidants are reported: Oxidation by sulfur generates dithiophosphinium salts, protonation or methylation gives dicationic phosphines, and coordination to 1 or 2 equiv of gold(I) chloride results in mono or bimetallic complexes, respectively. PMID:27355235

  3. Did you witness demonic possession? A response time analysis of the relationship between event plausibility and autobiographical beliefs.

    PubMed

    Mazzoni, Gilana

    2007-04-01

    This study tested the hypothesis that the search for information pertinent to answering the question "Did event x happen to you?" is preceded by a preliminary plausibility assessment, the outcome of which affects the amount of effort invested in the search. Undergraduate students were asked to assess the plausibility of six events and subsequently to rate their belief that each event had happened to them before the age of 6. Unknown to them, response times (RTs) for answering the belief questions were also recorded. RTs for making belief judgments were more highly correlated with plausibility than with belief, and were significantly associated with plausibility even when belief ratings were controlled. As predicted, RTs were very short when the event was deemed highly implausible and increased sharply if the event was deemed at least somewhat plausible; significant but less pronounced increases in RTs followed as plausibility increased further. PMID:17694913

  4. Virucidal Properties of Bioceramic Derived from Chicken Feces pH 13 and its Stability in Harsh Environments.

    PubMed

    Thammakarn, Chanathip; Sangsriratanakul, Natthanan; Ishida, Yuki; Suguro, Atsushi; Yamada, Masashi; Toyofuku, Chiharu; Nakajima, Katsuhiro; Kitazawa, Minori; Ota, Mari; Hakim, Hakimullah; Alam, Md Shahin; Shoham, Dany; Takehara, Kazuaki

    2016-09-01

    Bioceramic derived from chicken feces (BCX) is a material produced by a sintering process for the purpose of use in animal farms to control livestock infectious diseases. In the present study, BCX at pH 13 was evaluated for the durability of its virucidal activity in simulated field conditions. First it was shown that BCX had activity toward Newcastle disease virus, infectious bursal disease virus, and goose parvovirus within 3 min and toward avian influenza virus (AIV) within 1 hr. BCX was further tested by keeping it under simulated harsh environmental conditions with sunlight for several weeks as well as by repeatedly soaking it with water and drying under sunlight many times. After sampling every 2 consecutive weeks and every 2 (of 9) consecutive resuspensions, BCX was evaluated for its efficacy against AIV. Evaluation under the harsh conditions illustrated that BCX could retain its satisfactory efficacy toward AIV throughout 7 wk and through 9 resuspensions. It is hence concluded that BCX is an excellent material for applying in livestock farming as a trapping disinfectant, due to its efficacy to inactivate various viruses, and that this efficacy is prolonged even under harsh environmental conditions. PMID:27610720

  5. A newly identified berberine derivative induces cancer cell senescence by stabilizing endogenous G-quadruplexes and sparking a DNA damage response at the telomere region

    PubMed Central

    Xiong, Yun-Xia; Su, Hua-Fei; Lv, Peng; Ma, Yan; Wang, Shi-Ke; Miao, Hui; Liu, Hui-Yun; Tan, Jia-Heng; Ou, Tian-Miao; Gu, Lian-Quan; Huang, Zhi-Shu

    2015-01-01

    The guanine-rich sequences are able to fold into G-quadruplexes in living cells, making these structures promising anti-cancer drug targets. In the current study, we identified a small molecule, Ber8, from a series of 9-substituted berberine derivatives and found that it could induce acute cell growth arrest and senescence in cancer cells, but not in normal fibroblasts. Further analysis revealed that the cell growth arrest was directly associated with apparent cell cycle arrest, cell senescence, and profound DNA damage at the telomere region. Significantly, our studies also provided evidence that Ber8 could stabilize endogenous telomeric G-quadruplexes structures in cells. Ber8 could then induce the delocalization of TRF1 and POT1 from the telomere accompanied by a rapid telomere uncapping. These results provide compelling insights into direct binding of telomeric G-quadruplexes and might contribute to the development of more selective, effective anticancer drugs. PMID:26462146

  6. Transmembrane Photoredox in Model Protocellular Systems. Polycyclic Aromatic Hydrocarbons as Plausible Light-harvesting/Electron Transfer Catalysts

    NASA Astrophysics Data System (ADS)

    Cape, J. L.; Monnard, P.-A.; Ziock, H.-J.; Boncella, J. M.

    2010-04-01

    Mechanistic studies of transmembrane photoredox in a model protocell system indicate a plausible role for membrane solublized PAH species as primitive ‘photosynthetic' energy transduction catalysts.

  7. Sintering Effects on Morphology, Thermal Stability and Surface Area of Sol-Gel Derived Nano-Hydroxyapatite Powder

    NASA Astrophysics Data System (ADS)

    Kapoor, Seema; Batra, Uma; Kohli, Suchita

    2011-12-01

    TEM showed that the nanopowder sintered at 600 °C is composed of hydroxyapatite nanoparticles (26.0-45.6 nm), which is well in agreement with the crystallite size calculated using XRD data. TGA study showed the thermal stability of the synthesized nano-HAP powder. The BET surface area decreased with increase in sintering temperature.

  8. Sintering Effects on Morphology, Thermal Stability and Surface Area of Sol-Gel Derived Nano-Hydroxyapatite Powder

    SciTech Connect

    Kapoor, Seema; Batra, Uma; Kohli, Suchita

    2011-12-12

    at 1200 deg. C. Photomicrograph of TEM showed that the nanopowder sintered at 600 deg. C is composed of hydroxyapatite nanoparticles (26.0-45.6 nm), which is well in agreement with the crystallite size calculated using XRD data. TGA study showed the thermal stability of the synthesized nano-HAP powder. The BET surface area decreased with increase in sintering temperature.

  9. Monitoring the biology stability of human umbilical cord-derived mesenchymal stem cells during long-term culture in serum-free medium.

    PubMed

    Chen, Gecai; Yue, Aihuan; Ruan, Zhongbao; Yin, Yigang; Wang, Ruzhu; Ren, Yin; Zhu, Li

    2014-12-01

    Mesenchymal stem cells (MSCs) are multipotent adult stem cells that have an immunosuppressive effect. The biological stability of MSCs in serum-free medium during long-term culture in vitro has not been elucidated clearly. The morphology, immunophenotype and multi-lineage potential were analyzed at passages 3, 5, 10, 15, 20, and 25 (P3, P5, P10, P15, P20, and P25, respectively). The cell cycle distribution, apoptosis, and karyotype of human umbilical cord-derived (hUC)-MSCs were analyzed at P3, P5, P10, P15, P20, and P25. From P3 to P25, the three defining biological properties of hUC-MSCs [adherence to plastic, specific surface antigen expression, multipotent differentiation potential] met the standards proposed by the International Society for Cellular Therapy for definition of MSCs. The cell cycle distribution analysis at the P25 showed that the percentage of cells at G0/G1 was increased, compared with the cells at P3 (P < 0.05). Cells at P25 displayed an increase in the apoptosis rate (to 183 %), compared to those at P3 (P < 0.01). Within subculture generations 3-20 (P3-P20), the differences between the cell apoptotic rates were not statistically significant (P > 0.05). There were no detectable chromosome eliminations, displacements, or chromosomal imbalances, as assessed by the karyotyping guidelines of the International System for Human Cytogenetic Nomenclature (ISCN, 2009). Long-term culture affects the biological stability of MSCs in serum-free MesenCult-XF medium. MSCs can be expanded up to the 25th passage without chromosomal changes by G-band. The best biological activity period and stability appeared between the third to 20th generations. PMID:24407613

  10. A model for triple helix formation on human telomerase reverse transcriptase (hTERT) promoter and stabilization by specific interactions with the water soluble perylene derivative, DAPER.

    PubMed

    Rossetti, Luigi; D'Isa, Giuliana; Mauriello, Clementina; Varra, Michela; De Santis, Pasquale; Mayol, Luciano; Savino, Maria

    2007-08-01

    The promoter of human telomerase reverse transcriptase (hTERT) gene, in the region from -1000 to +1, contains two homopurine-homopyrimidine sequences (-835/-814 and -108/-90), that can be considered as potential targets to triple helix forming oligonucleotides (TFOs) for applying antigene strategy. We have chosen the sequence (-108/-90) on the basis of its unfavorable chromatin organization, evaluated by theoretical nucleosome positioning and nuclease hypersensitive sites mapping. On this sequence, anti-parallel triplex with satisfactory thermodynamic stability is formed by two TFOs, having different lengths. Triplex stability is significantly increased by specific interactions with the perylene derivative N,N'-bis[3,3'-(dimethylamino) propylamine]-3,4,9,10-perylenetetracarboxylic diimide (DAPER). Since DAPER is a symmetric molecule, the induced Circular Dichroism (CD) spectra in the range 400-600 nm allows us to obtain information on drug binding to triplex and duplex DNA. The drug-induced ellipticity is significantly higher in the case of triplex with respect to duplex and, surprisingly, it increases at decreasing of DNA. A model is proposed where self-stacked DAPER binds to triplex or to duplex narrow grooves. PMID:17560709

  11. (212)Pb@C(60) and its water-soluble derivatives: synthesis, stability, and suitability for radioimmunotherapy.

    PubMed

    Diener, Michael D; Alford, John M; Kennel, Stephen J; Mirzadeh, Saed

    2007-04-25

    Fullerenes could potentially play a valuable role in radioimmunotherapy by more stably encapsulating radionuclides, especially where conventional chelation chemistry is inadequate due to the physical and/or chemical properties of the radionuclide. One of the therapeutically useful radionuclides that requires improved containment in vivo is 212Pb (tau1/2 = 10.6 h), the beta-emitting parent to alpha-emitting 212Bi (tau1/2 = 60.6 min). Myelotoxicity resulting from the accumulation of 212Pb in the bone marrow has limited the use of this radionuclide despite its favorable decay characteristics. In this work, 212Pb@C60 and its malonic ester derivatives were prepared for the first time by allowing the 212Pb to recoil into C60 following alpha-decay from its parent, 0.15-s 216Po, generated in situ from the decay of 224Ra (tau1/2 = 15 days). Repeated washing of the organic phase containing the 212Pb@C60 malonic esters with challenge solutions containing cold Pb2+ ions demonstrated that some of the 212Pb could not be exchanged and was apparently inside of the fullerenes. Malonic esters of endohedral alpha-emitting 213Bi (tau1/2 = 45 min) fullerenes were prepared by an analogous procedure. Following acidification of the esters, a preliminary biodistribution study in mice was performed with the untargeted water-soluble radiofullerenes. It was found that 212Pb did not accumulate in bone after being administered as an endohedral fullerene, in contrast to results with polyhydroxylated radiofullerenes and conventional polyaminocarboxylate chelators for 212Pb. The results indicate that 212Pb is held more tightly in the fullerene than in other methods and suggest that fullerenes may have an important role in the targeted delivery of 212Pb. PMID:17394315

  12. Submicron mineral structures control the stabilization of litter-derived organic matter in soils - A NanoSIMS study

    NASA Astrophysics Data System (ADS)

    Vogel, Cordula; Mueller, Carsten W.; Höschen, Carmen; Buegger, Franz; Heister, Katja; Schulz, Stefanie; Schloter, Michael; Kögel-Knabner, Ingrid

    2014-05-01

    The sequestration of carbon and nitrogen by clay-sized particles in soils is well established. However, in the most cases, the complex structure of the organo-mineral associations remain a black box due to the common measurements of soil fractions as a whole. By combining nano-scale secondary ion mass spectrometry (NanoSIMS) with isotopic tracing it is possible to study the formation and spatial heterogeneity of organo-mineral associations. NanoSIMS enables the detection of up to seven secondary ion species (e.g. 13C-, 12N15N-, 27Al16O-, 56Fe16O-) simultaneously, to generate a submicron-scale image of the elemental and isotopic composition (e.g. 13C, 15N, Al and Fe) down to a lateral resolution of ~150 nm. Therefore this technique can be used to study organo-mineral associations at the relevant scale. The aim of our study was to follow the formation of organo-mineral associations over different time steps and the distribution of C and N by imaging the complex arrangement between soil mineral surfaces and litter-derived organic matter (OM). Parallel to the determination of the isotopic N and C composition of bulk soil and soil fractions (combined density and particle size fractionation) using isotope ratio mass spectrometry (IRMS), the spatial distribution of the OM was investigated by NanoSIMS analysis of the clay-sized fraction. In our study we show that only some of the clay-sized surfaces bind OM. Surprisingly, less than 19% of the mineral areas visible by scanning electron microscopy and NanoSIMS show an OM attachment. We demonstrate that mineral clusters with rough surfaces exhibit the preferential binding spots for OM. By combining NanoSIMS and isotopic tracing, we distinguish between new labelled and pre-existing OM and show that new OM is preferentially attached to already present organo-mineral clusters. Vogel, C., Mueller, C.W., Höschen, C., Buegger, F., Heister, K., Schulz, S., Schloter, M., Kögel-Knabner, I., 2014. Submicron structures provide

  13. New synthesis of a high molecular weight ligand derived from dota; thermodynamic stability of the MRI contrast agent formed with gadolinium.

    PubMed

    Pierrard, Jean-Claude; Rimbault, Jean; Aplincourt, Michel; Le Greneur, Soizic; Port, Marc

    2008-01-01

    The new total synthesis in four steps of the compound P1041 is reported. This compound is a high molecular mass ligand (MW 6.32 kDa) derived from dota in which the four substituents are hydroxylated and contain amidic groups. The attribution of the nine protonation constants of P1041 is based on the comparison with the behaviour of the precursor ligands dota and tced, a tetracarboxylated derivative of dota. From these results, the studies of the systems P1041/Na(+) and P1041/Gd(3+) lead to the determination of the stability constants corresponding to the three species Na(P1041)H(h) (h = 0, 2 or 4) and to the five complexes Gd(P1041)H(h) (h = 0, 2, 3, 4 or 5). The complexing ability of P1041 towards Gd(3+) is compared with those of dota and tced. At physiological pH = 7.4, the very stable species Gd(P1041)H(4) (-) (currently named P792 in the literature) of this rapid clearance blood pool agent is predominant. PMID:19072772

  14. Anti-AIDS Agents 78 †. Design, Synthesis, Metabolic Stability Assessment, and Antiviral Evaluation of Novel Betulinic Acid Derivatives as Potent Anti-Human Immunodeficiency Virus (HIV) Agents

    PubMed Central

    Qian, Keduo; Yu, Donglei; Chen, Chin-Ho; Huang, Li; Morris-Natschke, Susan L.; Nitz, Theodore J.; Salzwedel, Karl; Reddick, Mary; Allaway, Graham P.; Lee, Kuo-Hsiung

    2009-01-01

    In a continuing study of potent anti-HIV agents, seventeen 28,30-disubstituted betulinic acid (BA, 1) derivatives, as well as seven novel 3,28-disubstituted BA analogs were designed, synthesized, and evaluated for in vitro antiviral activity. Among them, compound 21 showed an improved solubility and equal anti-HIV potency (EC50: 0.09 μM), when compared to HIV entry inhibitors 3b (IC9564) and 4 (A43-D). Using a cyclic secondary amine to form the C-28 amide bond increased the metabolic stability of the derivatives significantly in pooled human liver microsomes. The most potent compounds 47 and 48 displayed potent anti-HIV activity with EC50 values of 0.007 μM and 0.006 μM, respectively. These results are slightly better than that of bevirimat (2), which is currently in Phase IIb clinical trials. Compounds 47 and 48 should serve as attractive promising leads to develop next generation, metabolically stable, 3,28-disubstituted bifunctional HIV-1 inhibitors as clinical trials candidates. PMID:19388685

  15. Spelling in oral deaf and hearing dyslexic children: A comparison of phonologically plausible errors.

    PubMed

    Roy, P; Shergold, Z; Kyle, F E; Herman, R

    2014-11-01

    A written single word spelling to dictation test and a single word reading test were given to 68 severe-profoundly oral deaf 10-11-year-old children and 20 hearing children with a diagnosis of dyslexia. The literacy scores of the deaf children and the hearing children with dyslexia were lower than expected for children of their age and did not differ from each other. Three quarters of the spelling errors of hearing children with dyslexia compared with just over half the errors of the oral deaf group were phonologically plausible. Expressive vocabulary and speech intelligibility predicted the percentage of phonologically plausible errors in the deaf group only. Implications of findings for the phonological decoding self-teaching model and for supporting literacy development are discussed. PMID:25462488

  16. Identifying plausible genetic models based on association and linkage results: application to type 2 diabetes.

    PubMed

    Guan, Weihua; Boehnke, Michael; Pluzhnikov, Anna; Cox, Nancy J; Scott, Laura J

    2012-12-01

    When planning resequencing studies for complex diseases, previous association and linkage studies can constrain the range of plausible genetic models for a given locus. Here, we explore the combinations of causal risk allele frequency (RAFC ) and genotype relative risk (GRRC ) consistent with no or limited evidence for affected sibling pair (ASP) linkage and strong evidence for case-control association. We find that significant evidence for case-control association combined with no or moderate evidence for ASP linkage can define a lower bound for the plausible RAFC . Using data from large type 2 diabetes (T2D) linkage and genome-wide association study meta-analyses, we find that under reasonable model assumptions, 23 of 36 autosomal T2D risk loci are unlikely to be due to causal variants with combined RAFC < 0.005, and four of the 23 are unlikely to be due to causal variants with combined RAFC < 0.05. PMID:22865662

  17. Individual differences in syntactic ambiguity resolution: Readers vary in their use of plausibility information

    PubMed Central

    Long, Debra L.; Prat, Chantel S.

    2009-01-01

    Two experiments investigated the relation between individual differences in working memory capacity and differences in the efficiency of syntactic processing. In one experiment, readers comprehended sentences containing main-verb/reduced-relative ambiguities that all resolved to the reduced-relative interpretation. High-span (but not low-span) readers processed sentences more slowly when the sentences were biased to the preferred, main-verb interpretation than when they were biased to the reduced-relative interpretation. Moreover, high-span (but not low-span) readers used information about the plausibility of the different interpretations even though low-span readers appeared to possess the requisite knowledge. In Experiment 2, readers received intensive exposure to sentences with main-verb/reduced-relative ambiguities. Exposure enhanced low-span readers’ use of plausibility information. Moreover, the effect of exposure generalized to sentences that were not included in the training materials. PMID:18426067

  18. Effective Teacher Practice on the Plausibility of Human-Induced Climate Change

    NASA Astrophysics Data System (ADS)

    Niepold, F.; Sinatra, G. M.; Lombardi, D.

    2013-12-01

    Climate change education programs in the United States seek to promote a deeper understanding of the science of climate change, behavior change and stewardship, and support informed decision making by individuals, organizations, and institutions--all of which are summarized under the term 'climate literacy.' The ultimate goal of climate literacy is to enable actors to address climate change, both in terms of stabilizing and reducing emissions of greenhouse gases, but also an increased capacity to prepare for the consequences and opportunities of climate change. However, the long-term nature of climate change and the required societal response involve the changing students' ideas about controversial scientific issues which presents unique challenges for educators (Lombardi & Sinatra, 2010; Sinatra & Mason, 2008). This session will explore how the United States educational efforts focus on three distinct, but related, areas: the science of climate change, the human-climate interaction, and using climate education to promote informed decision making. Each of these approaches are represented in the Atlas of Science Literacy (American Association for the Advancement of Science, 2007) and in the conceptual framework for science education developed at the National Research Council (NRC) in 2012. Instruction to develop these fundamental thinking skills (e.g., critical evaluation and plausibility reappraisal) has been called for by the Next Generation Science Standards (NGSS) (Achieve, 2013), an innovative and research based way to address climate change education within the decentralized U.S. education system. However, the promise of the NGSS is that students will have more time to build mastery on the subjects, but the form of that instructional practice has been show to be critical. Research has show that effective instructional activities that promote evaluation of evidence improve students' understanding and acceptance toward the scientifically accepted model of human

  19. Why there was a useful plausible analogy between geodesic domes and spherical viruses.

    PubMed

    Morgan, Gregory J

    2006-01-01

    In 1962, Donald Caspar and Aaron Klug published their classic theory of virus structure. They developed their theory with an explicit analogy between spherical viruses and Buckminster Fuller's geodesic domes. In this paper, I use the spherical virus-geodesic dome case to develop an account of analogy and deductive analogical inference based on the notion of an isomorphism. I also consider under what conditions there is a good reason to claim an experimentally untested analogy is plausible. PMID:17702504

  20. What happened (and what didn’t): Discourse constraints on encoding of plausible alternatives

    PubMed Central

    Fraundorf, Scott H.; Benjamin, Aaron S.; Watson, Duane G.

    2013-01-01

    Three experiments investigated how font emphasis influences reading and remembering discourse. Although past work suggests that contrastive pitch contours benefit memory by promoting encoding of salient alternatives, it is unclear both whether this effect generalizes to other forms of linguistic prominence and how the set of alternatives is constrained. Participants read discourses in which some true propositions had salient alternatives (e.g., British scientists found the endangered monkey when the discourse also mentioned French scientists) and completed a recognition memory test. In Experiments 1 and 2, font emphasis in the initial presentation increased participants’ ability to later reject false statements about salient alternatives but not about unmentioned items (e.g., Portuguese scientists). In Experiment 3, font emphasis helped reject false statements about plausible alternatives, but not about less plausible alternatives that were nevertheless established in the discourse. These results suggest readers encode a narrow set of only those alternatives plausible in the particular discourse. They also indicate that multiple manipulations of linguistic prominence, not just prosody, can lead to consideration of alternatives. PMID:24014934

  1. THE EFFECT OF PLAUSIBILITY ON SENTENCE COMPREHENSION AMONG OLDER ADULTS AND ITS RELATION TO COGNITIVE FUNCTIONS

    PubMed Central

    Yoon, Jungmee; Campanelli, Luca; Goral, Mira; Marton, Klara; Eichorn, Naomi; Obler, Loraine K.

    2016-01-01

    Background/Study Context Older adults show age-related decline in complex-sentence comprehension. This has been attributed to a decrease in cognitive abilities that may support language processing, such as working memory (e.g., Caplan, DeDe, Waters, & Michaud, 2011,Psychology and Aging, 26, 439–450). The authors examined whether older adults have difficulty comprehending semantically implausible sentences and whether specific executive functions contribute to their comprehension performance. Methods Forty-two younger adults (aged 18–35) and 42 older adults (aged 55–75) were tested on two experimental tasks: a multiple negative comprehension task and an information processing battery. Results Both groups, older and younger adults, showed poorer performance for implausible sentences than for plausible sentences; however, no interaction was found between plausibility and age group. A regression analysis revealed that inhibition efficiency, as measured by a task that required resistance to proactive interference, predicted comprehension of implausible sentences in older adults only. Consistent with the compensation hypothesis, the older adults with better inhibition skills showed better comprehension than those with poor inhibition skills. Conclusion The findings suggest that semantic implausibility, along with syntactic complexity, increases linguistic and cognitive processing loads on auditory sentence comprehension. Moreover, the contribution of inhibitory control to the processing of semantic plausibility, particularly among older adults, suggests that the relationship between cognitive ability and language comprehension is strongly influenced by age. PMID:25978447

  2. Risk management for plausibly hormetic environmental carcinogens: the case of radon.

    PubMed

    Bogen, K T; Layton, D W

    1998-08-01

    Risk management typically involves efforts to reduce human exposures by establishing regulations that limit the concentration of the substance in environmental media. In cases where a substance is widely used in commerce or is naturally occurring in the environment, compliance costs can be substantial because of nationwide requirements to add expensive control technologies. Uncertainties in a dose-response function further impact risk management decisions because they may correspond to large differences in health benefit per unit exposure reduction. These problems are highlighted in the case of plausibly hormetic environmental carcinogens, for which a linear-no-threshold (LNT) dose-response model has been the traditional regulatory default assumption. In this case, model uncertainty is pivotal, and risk management is consequently inherently controversial. However, marginal cost functions that arise for plausibly hormetic carcinogens are expected to possess a common analytic feature that may be particularly useful for this type of risk management problem. Specifically, marginal cost functions in this context are expected to have roots reflecting contaminant concentration values above which regulatory goals may be optimally placed subject to cost constraints. Here we illustrate this heuristic feature in the case of residential radon, using both a LNT model and a biologically plausible hormetic model to predict associated risks of lung cancer mortality. PMID:9756142

  3. The Time Course of Plausibility Effects on Eye Movements in Reading: Evidence from Noun-Noun Compounds

    ERIC Educational Resources Information Center

    Staub, Adrian; Rayner, Keith; Pollatsek, Alexander; Hyona, Jukka; Majewski, Helen

    2007-01-01

    Readers' eye movements were monitored as they read sentences containing noun-noun compounds that varied in frequency (e.g., elevator mechanic, mountain lion). The left constituent of the compound was either plausible or implausible as a head noun at the point at which it appeared, whereas the compound as a whole was always plausible. When the head…

  4. Stability of a double inverted pendulum model during human quiet stance with continuous delay feedback control.

    PubMed

    Suzuki, Yasuyuki; Nomura, Taishin; Morasso, Pietro

    2011-01-01

    Recent debate about neural mechanisms for stabilizing human upright quiet stance focuses on whether the active and time delay neural feedback control generating muscle torque is continuous or intermittent. A single inverted pendulum controlled by the active torque actuating the ankle joint has often been used for the debate on the presumption of well-known ankle strategy hypothesis claiming that the upright quiet stance can be stabilized mostly by the ankle torque. However, detailed measurements are showing that the hip joint angle exhibits amount of fluctuations comparable with the ankle joint angle during natural postural sway. Here we analyze a double inverted pendulum model during human quiet stance to demonstrate that the conventional proportional and derivative delay feedback control, i.e., the continuous delay PD control with gains in the physiologically plausible range is far from adequate as the neural mechanism for stabilizing human upright quiet stance. PMID:22256061

  5. Mechanism of inhibition of human leucocyte elastase by beta-lactams. 2. Stability, reactivation kinetics, and products of beta-lactam-derived E-I complexes.

    PubMed

    Green, B G; Chabin, R; Mills, S; Underwood, D J; Shah, S K; Kuo, D; Gale, P; Maycock, A L; Liesch, J; Burgey, C S

    1995-11-01

    The monocyclic beta-lactams reported by Knight et al. [Knight, W. B., et al. (1992) Biochemistry 31, 8160; Chabin, R., et al. (1993) Biochemistry 32, 8970] as inhibitors of human leucocyte elastase (HLE) produce stable HLE-inhibitor complexes that slowly reactivate with half-lives ranging from less than 1 to 15 h at 37 degrees C. The complexes produced between PPE and two C-3 dimethyl-substituted beta-lactams are less stable than those produced between HLE and analogous C-3 diethyl-substituted lactams. The stability of the HLE-I complexes is governed primarily by the structure of the substituted urea portion of the inhibitors and not by the identity or presence of a leaving group at C-4 of the lactam ring. In some cases substitutions on the urea portion of the inhibitors yielded complexes that displayed biphasic reactivation kinetics. This suggests the presence of at least two different complexes. The stereochemistry of the leaving group at C-4 has a small effect on the stability of the final complex (1.3-2-fold); therefore, the identity of the final complex is dependent upon the initial stereochemistry at that position. The stability of the complexes was relatively insensitive to hydroxylamine, which suggests that the acyl-enzymes are protected from nucleophilic "rescue". The rate of reactivation of the complex derived from L-680,833,[S-R*,S*)]-4-[(1-(((1-(4- methylphenyl)butyl)amino)carbonyl)-3,3-diethyl-2-oxo-4-azetidinyl)ben zeneacetic acid, was pH independent, while the L-684,481, (R)-(1-(((1-(4-methylphenyl)butyl)amino)carbonyl)-3,3-diethyl-2-azeti din one generated complex displayed a pH-dependent reactivation rate. In the latter case, the increase in reactivation rate with pH displayed a pKa of 7.2. This is consistent with the requirement for base catalysis by the active site histidine to regenerate enzymatic activity. Reactivation of the L-680,833-derived complex produced different products as a function of pH, suggesting two different pH-dependent routes

  6. Stability of microsomal monooxygenases in murine liver S9 fractions derived from phenobarbital and beta-naphthoflavone induced animals under various long-term conditions of storage.

    PubMed

    Bauer, C; Corsi, C; Paolini, M

    1994-01-01

    The aim of this study was to define the long-term stability of metabolizing enzymes in activating preparations for short-term genotoxicity bioassays under various storage conditions. Expressions of cytochrome P450 content, NADPH-cytochrome (P450) c-reductase activity, and of the several monooxygenases, such as aminopyrine N-demethylase (class IIIA P450), p-nitroanisole O-demethylase (mixed), dinemorphan N-demethylase (IIB1), ethoxyresorufin O-deethylase (IA1), ethoxycoumarin O-deethylase (mixed), and pentoxyresorufin O-dealkylase (IIB1), were examined in S9 fractions derived from Na-phenobarbital (PB) plus beta-naphthoflavone (beta-NF) induced male and female mice, stored at -80 degrees C, or lyophilized and stored at -20 degrees C. Lipid peroxidation was also determined. Cytochrome P450 and the associated activities were decreased by 30-82% within 9 months of storage. The pattern and degree of relative stabilities were different for the various isoforms. The IA1-like activity, for example, was much more stable (approximately 49% loss) than IIB1-like activities (up to 82% loss). In general, lyophilized enzymes were less stable than directly frozen preparations. In addition, immediately after freeze-drying (lyophilization), a marked decrease in activity of up to 35% was observed. On the contrary, demethylation of aminopyrine and p-nitroanisole remains almost constant over 6 months storage at -196 degrees C. The results obtained indicate that either fresh, daily made S9 fractions or, alternatively, fractions stored in liquid nitrogen (up to 6 months) are recommended for mutagenesis studies. PMID:7910416

  7. Adipose derived stem cells: efficiency, toxicity, stability of BrdU labeling and effects on self-renewal and adipose differentiation.

    PubMed

    Lequeux, Charlotte; Oni, Georgette; Mojallal, Ali; Damour, Odile; Brown, Spencer A

    2011-05-01

    5-bromo-2-deoxyurudine (BrdU) can be used as a methodological tool for in vivo investigations following in vitro prelabeling of isolated stem cells for subsequent cell tracking within the recipient host. The objective of this study was to determine how useful BrdU may be as a labeling modality for adipose derived stem cells (ASC) by examining BrdU toxicity, BrdU intracellular stability, and potential effects on ASC differentiation. Porcine and human ASC (pASC and hASC, respectively) were labeled with BrdU at 5 or 10 μM for 2, 6, 24, and 48 h. BrdU toxicity and stability over time in monolayer cultures, in 3-D collagen scaffolds implanted to a porcine model and after thawing from long-term storage were evaluated by MTT assays and immunohistochemistry. ASC differentiation was evaluated by Oil Red O staining. BrdU was not cytotoxic at all tested concentrations and incubation times. BrdU color intensity within each cell and the number of ASC labeled with BrdU decreased as a function of both incubation time and BrdU concentrations. Labeling intensities decreased over time and were undetectable after 6 passages for pASC and 4 passages for hASC. In 3-D scaffolds, BrdU-labeled ASC were identifiable after 90 days of in vitro cultures and for 30 days in a porcine model. BrdU did not prevent preadipocyte differentiation and BrdU labeling was still detectable after subsequent thawing after long-term storage of ASC. BrdU is an excellent candidate reagent to label and track ASC that will allow distinction between BrdU-labeled donor cells and host cells. The data provides a foundation for conducting future tissue engineering projects using BrdU-labeled ASC. PMID:21246262

  8. Mass Spectrometry Based Identification of Geometric Isomers during Metabolic Stability Study of a New Cytotoxic Sulfonamide Derivatives Supported by Quantitative Structure-Retention Relationships

    PubMed Central

    Belka, Mariusz; Hewelt-Belka, Weronika; Sławiński, Jarosław; Bączek, Tomasz

    2014-01-01

    A set of 15 new sulphonamide derivatives, presenting antitumor activity have been subjected to a metabolic stability study. The results showed that besides products of biotransformation, some additional peaks occurred in chromatograms. Tandem mass spectrometry revealed the same mass and fragmentation pathway, suggesting that geometric isomerization occurred. Thus, to support this hypothesis, quantitative structure-retention relationships were applied. Human liver microsomes were used as an in vitro model of metabolism. The biotransformation reactions were tracked by liquid chromatography assay and additionally, fragmentation mass spectra were recorded. In silico molecular modeling at a semi-empirical level was conducted as a starting point for molecular descriptor calculations. A quantitative structure-retention relationship model was built applying multiple linear regression based on selected three-dimensional descriptors. The studied compounds revealed high metabolic stability, with a tendency to form hydroxylated biotransformation products. However, significant chemical instability in conditions simulating human body fluids was noticed. According to literature and MS data geometrical isomerization was suggested. The developed in sillico model was able to describe the relationship between the geometry of isomer pairs and their chromatographic retention properties, thus it supported the hypothesis that the observed pairs of peaks are most likely geometric isomers. However, extensive structural investigations are needed to fully identify isomers’ geometry. An effort to describe MS fragmentation pathways of novel chemical structures is often not enough to propose structures of potent metabolites and products of other chemical reactions that can be observed in compound solutions at early drug discovery studies. The results indicate that the relatively non-expensive and not time- and labor-consuming in sillico approach could be a good supportive tool assisting the

  9. Mass spectrometry based identification of geometric isomers during metabolic stability study of a new cytotoxic sulfonamide derivatives supported by quantitative structure-retention relationships.

    PubMed

    Belka, Mariusz; Hewelt-Belka, Weronika; Sławiński, Jarosław; Bączek, Tomasz

    2014-01-01

    A set of 15 new sulphonamide derivatives, presenting antitumor activity have been subjected to a metabolic stability study. The results showed that besides products of biotransformation, some additional peaks occurred in chromatograms. Tandem mass spectrometry revealed the same mass and fragmentation pathway, suggesting that geometric isomerization occurred. Thus, to support this hypothesis, quantitative structure-retention relationships were applied. Human liver microsomes were used as an in vitro model of metabolism. The biotransformation reactions were tracked by liquid chromatography assay and additionally, fragmentation mass spectra were recorded. In silico molecular modeling at a semi-empirical level was conducted as a starting point for molecular descriptor calculations. A quantitative structure-retention relationship model was built applying multiple linear regression based on selected three-dimensional descriptors. The studied compounds revealed high metabolic stability, with a tendency to form hydroxylated biotransformation products. However, significant chemical instability in conditions simulating human body fluids was noticed. According to literature and MS data geometrical isomerization was suggested. The developed in sillico model was able to describe the relationship between the geometry of isomer pairs and their chromatographic retention properties, thus it supported the hypothesis that the observed pairs of peaks are most likely geometric isomers. However, extensive structural investigations are needed to fully identify isomers' geometry. An effort to describe MS fragmentation pathways of novel chemical structures is often not enough to propose structures of potent metabolites and products of other chemical reactions that can be observed in compound solutions at early drug discovery studies. The results indicate that the relatively non-expensive and not time- and labor-consuming in sillico approach could be a good supportive tool assisting the

  10. Theoretical study of stability and charge-transport properties of coronene molecule and some of its halogenated derivatives: A path to ambipolar organic-based materials?

    SciTech Connect

    Sancho-García, J. C. Pérez-Jiménez, A. J.

    2014-10-07

    We have carefully investigated the structural and electronic properties of coronene and some of its fluorinated and chlorinated derivatives, including full periphery substitution, as well as the preferred orientation of the non-covalent dimer structures subsequently formed. We have paid particular attention to a set of methodological details, to first obtain single-molecule magnitudes as accurately as possible, including next the use of modern dispersion-corrected methods to tackle the corresponding non-covalently bound dimers. Generally speaking, this class of compounds is expected to self-assembly in neighboring π-stacks with dimer stabilization energies ranging from –20 to –30 kcal mol{sup −1} at close distances around 3.0–3.3 Å. Then, in a further step, we have also calculated hole and electron transfer rates of some suitable candidates for ambipolar materials, and corresponding charge mobility values, which are known to critically depend on the supramolecular organization of the samples. For coronene and per-fluorinated coronene, we have found high values for their hopping rates, although slightly smaller for the latter due to an increase (decrease) of the reorganization energies (electronic couplings)

  11. On the Electronic Spectroscopy of Closed Shell Cations Derived from Resonance Stabilized Radicals: Insights from Theory and Franck-Condon Analysis

    NASA Astrophysics Data System (ADS)

    Troy, Tyler P.; Kable, Scott H.; Schmidt, Timothy W.; Reid, Scott A.

    2012-06-01

    Recent attention has been directed on closed shell aromatic cations as potential carriers of the diffuse interstellar bands. The spectra of mass-selected, matrix-isolated benzylium and tropylium cations were recently reported [Nagy, A., Fulara, J., Garkusha, I. and Maier, J. P. (2011), Angew. Chem. Int. Ed., 50: 3022-3025]. The benzylium spectrum shows an extended progression in a low frequency (510 cm-1) ring distortion mode. Modeling of the benzylium spectrum using (TD)DFT and MCSCF-PT2 methods in concert with multidimensional Franck-Condon (FC) analysis is found to yield excellent agreement with the experimental spectrum. We extended this analysis to larger (2 and 3 ring) PAH cations derived from resonance stabilized radicals, which are predicted to show strong S0 → Sn transitions in the visible region. The FC progression is significantly quenched in the larger species, and our results for 1-napthylmethylium are in excellent agreement with very recent experiments [Nagy, A., Fulara, J., and Maier, J. P. (2011), J. Am. Chem. Soc., 133, 19796]. Since carriers of the DIBs should exhibit spectra dominated by a single vibronic transition, our results demonstrate that closed-shell cations may present spectra with the required properties. Furthermore, the calculated ionization energies of a range of CSCs were found to be in the 13-14 eV range, consistent with variations in behaviour of the DIB carriers with respect to various astrophysical environments.

  12. Theoretical study of stability and charge-transport properties of coronene molecule and some of its halogenated derivatives: a path to ambipolar organic-based materials?

    PubMed

    Sancho-García, J C; Pérez-Jiménez, A J

    2014-10-01

    We have carefully investigated the structural and electronic properties of coronene and some of its fluorinated and chlorinated derivatives, including full periphery substitution, as well as the preferred orientation of the non-covalent dimer structures subsequently formed. We have paid particular attention to a set of methodological details, to first obtain single-molecule magnitudes as accurately as possible, including next the use of modern dispersion-corrected methods to tackle the corresponding non-covalently bound dimers. Generally speaking, this class of compounds is expected to self-assembly in neighboring π-stacks with dimer stabilization energies ranging from -20 to -30 kcal mol(-1) at close distances around 3.0-3.3 Å. Then, in a further step, we have also calculated hole and electron transfer rates of some suitable candidates for ambipolar materials, and corresponding charge mobility values, which are known to critically depend on the supramolecular organization of the samples. For coronene and per-fluorinated coronene, we have found high values for their hopping rates, although slightly smaller for the latter due to an increase (decrease) of the reorganization energies (electronic couplings). PMID:25296829

  13. Theoretical study of stability and charge-transport properties of coronene molecule and some of its halogenated derivatives: A path to ambipolar organic-based materials?

    NASA Astrophysics Data System (ADS)

    Sancho-García, J. C.; Pérez-Jiménez, A. J.

    2014-10-01

    We have carefully investigated the structural and electronic properties of coronene and some of its fluorinated and chlorinated derivatives, including full periphery substitution, as well as the preferred orientation of the non-covalent dimer structures subsequently formed. We have paid particular attention to a set of methodological details, to first obtain single-molecule magnitudes as accurately as possible, including next the use of modern dispersion-corrected methods to tackle the corresponding non-covalently bound dimers. Generally speaking, this class of compounds is expected to self-assembly in neighboring π-stacks with dimer stabilization energies ranging from -20 to -30 kcal mol-1 at close distances around 3.0-3.3 Å. Then, in a further step, we have also calculated hole and electron transfer rates of some suitable candidates for ambipolar materials, and corresponding charge mobility values, which are known to critically depend on the supramolecular organization of the samples. For coronene and per-fluorinated coronene, we have found high values for their hopping rates, although slightly smaller for the latter due to an increase (decrease) of the reorganization energies (electronic couplings).

  14. Plausibility and the Theoreticians' Regress: Constructing the evolutionary fate of stars

    NASA Astrophysics Data System (ADS)

    Ipe, Alex Ike

    2002-10-01

    This project presents a case-study of a scientific controversy that occurred in theoretical astrophysics nearly seventy years ago following the conceptual discovery of a novel phenomenon relating to the evolution and structure of stellar matter, known as the limiting mass. The ensuing debate between the author of the finding, Subrahmanyan Chandrasekhar and his primary critic, Arthur Stanley Eddington, witnessed both scientists trying to convince one another, as well as the astrophysical community, that their respective positions on the issue was the correct one. Since there was no independent criterion—that is, no observational evidence—at the time of the dispute that could have been drawn upon to test the validity of the limiting mass concept, a logical, objective resolution to the controversy was not possible. In this respect, I argue that the dynamics of the Chandrasekhar-Eddington debate succinctly resonates with Kennefick's notion of the Theoreticians' Regress. However, whereas this model predicts that such a regress can be broken if both parties in a dispute come to agree on who was in error and collaborate on a calculation whose technical foundation can be agreed to, I argue that a more pragmatic path by which the Theoreticians' Regress is broken is when one side in a dispute is able to construct its argument as being more plausible than that of its opponent, and is so successful in doing so, that its opposition is subsequently forced to withdraw from the debate. In order to adequately deal with the construction of plausibility in the context of scientific controversies, I draw upon Harvey's Plausibility Model as well as Pickering's work on the role socio-cultural factors play in the resolution of intellectual disputes. It is believed that the ideas embedded in these social- relativist-constructivist perspectives provide the most parsimonious explanation as to the reasons for the genesis and ultimate closure of this particular scientific controversy.

  15. A BIOMASS-BASED MODEL TO ESTIMATE THE PLAUSIBILITY OF EXOPLANET BIOSIGNATURE GASES

    SciTech Connect

    Seager, S.; Bains, W.; Hu, R.

    2013-10-01

    Biosignature gas detection is one of the ultimate future goals for exoplanet atmosphere studies. We have created a framework for linking biosignature gas detectability to biomass estimates, including atmospheric photochemistry and biological thermodynamics. The new framework is intended to liberate predictive atmosphere models from requiring fixed, Earth-like biosignature gas source fluxes. New biosignature gases can be considered with a check that the biomass estimate is physically plausible. We have validated the models on terrestrial production of NO, H{sub 2}S, CH{sub 4}, CH{sub 3}Cl, and DMS. We have applied the models to propose NH{sub 3} as a biosignature gas on a 'cold Haber World', a planet with a N{sub 2}-H{sub 2} atmosphere, and to demonstrate why gases such as CH{sub 3}Cl must have too large of a biomass to be a plausible biosignature gas on planets with Earth or early-Earth-like atmospheres orbiting a Sun-like star. To construct the biomass models, we developed a functional classification of biosignature gases, and found that gases (such as CH{sub 4}, H{sub 2}S, and N{sub 2}O) produced from life that extracts energy from chemical potential energy gradients will always have false positives because geochemistry has the same gases to work with as life does, and gases (such as DMS and CH{sub 3}Cl) produced for secondary metabolic reasons are far less likely to have false positives but because of their highly specialized origin are more likely to be produced in small quantities. The biomass model estimates are valid to one or two orders of magnitude; the goal is an independent approach to testing whether a biosignature gas is plausible rather than a precise quantification of atmospheric biosignature gases and their corresponding biomasses.

  16. [The reliable and plausible conclusions in the decisions of the forensic medical experts].

    PubMed

    Kovalev, A V; Shmarov, L A; Ten'kov, A A

    2016-01-01

    The authors characterize in brief the conclusions drawn by the forensic medical experts in the course of their professional activities with special reference to their reliability and plausibility. The most common errors creeping into the conclusions are discussed together with the approaches to their prevention and/or correction. This article continues a series of publications of the same authors concerning the main logical errors encountered in the conclusions of the forensic medical experts. The results of a deeper analysis of such errors will be published elsewhere. PMID:27030098

  17. Exploring discrepancies between quantitative validation results and the geomorphic plausibility of statistical landslide susceptibility maps

    NASA Astrophysics Data System (ADS)

    Steger, Stefan; Brenning, Alexander; Bell, Rainer; Petschko, Helene; Glade, Thomas

    2016-06-01

    Empirical models are frequently applied to produce landslide susceptibility maps for large areas. Subsequent quantitative validation results are routinely used as the primary criteria to infer the validity and applicability of the final maps or to select one of several models. This study hypothesizes that such direct deductions can be misleading. The main objective was to explore discrepancies between the predictive performance of a landslide susceptibility model and the geomorphic plausibility of subsequent landslide susceptibility maps while a particular emphasis was placed on the influence of incomplete landslide inventories on modelling and validation results. The study was conducted within the Flysch Zone of Lower Austria (1,354 km2) which is known to be highly susceptible to landslides of the slide-type movement. Sixteen susceptibility models were generated by applying two statistical classifiers (logistic regression and generalized additive model) and two machine learning techniques (random forest and support vector machine) separately for two landslide inventories of differing completeness and two predictor sets. The results were validated quantitatively by estimating the area under the receiver operating characteristic curve (AUROC) with single holdout and spatial cross-validation technique. The heuristic evaluation of the geomorphic plausibility of the final results was supported by findings of an exploratory data analysis, an estimation of odds ratios and an evaluation of the spatial structure of the final maps. The results showed that maps generated by different inventories, classifiers and predictors appeared differently while holdout validation revealed similar high predictive performances. Spatial cross-validation proved useful to expose spatially varying inconsistencies of the modelling results while additionally providing evidence for slightly overfitted machine learning-based models. However, the highest predictive performances were obtained for

  18. Higher Data Quality by Online Data-Entry and Automated Plausibility Checks

    NASA Astrophysics Data System (ADS)

    Pietragalla, Barbara; Sigg, Christian; Güsewell, Sabine; Clot, Bernard

    2014-05-01

    Long-term phenological observations are now recognized as important indicators for climate change impact studies. With the increased need for phenological data, there is also an increased need for higher data quality. Since 1951 MeteoSwiss has been operating a national phenological observation network. Currently the network consists of about 150 active stations observing up to 69 different phenophases. An important aim of a running three years project at MeteoSwiss is a further increase of the quality of the collected data. The higher data quality will be achieved by an automated procedure performing plausibility checks on the data and by online data-entry. Further measures such as intensified observer instructions and collection of more detailed metadata also contribute to a high data quality standard. The plausibility checks include the natural order of the phenophases within a species and also between different species (with regard to possible natural deviation). Additionally it will be checked if the observed date differs by less than two standard deviations from the average for this phenophase at the altitude of the station. A value outside of these limits is not necessarily a false value, since occurrences of extreme values will be beyond these limits. Therefore, within this check of the limits, the timing of the season of the respective year will also be taken into account. In case of an implausible value a comparison with other stations of the same region and sea level is proposed. A further possibility of data quality control could be to model the different phenophases statistically and to use this model for estimating the likelihood of observed values. An overall exploratory data analysis is currently performed providing a solid basis to implement the best possible methods for the plausibility checks. Important advantages of online data-entry are the near real-time availability of the data as well as the avoidance of various kinds of typical mistakes

  19. Stochastic Dynamics Underlying Cognitive Stability and Flexibility

    PubMed Central

    Ueltzhöffer, Kai; Armbruster-Genç, Diana J. N.; Fiebach, Christian J.

    2015-01-01

    Cognitive stability and flexibility are core functions in the successful pursuit of behavioral goals. While there is evidence for a common frontoparietal network underlying both functions and for a key role of dopamine in the modulation of flexible versus stable behavior, the exact neurocomputational mechanisms underlying those executive functions and their adaptation to environmental demands are still unclear. In this work we study the neurocomputational mechanisms underlying cue based task switching (flexibility) and distractor inhibition (stability) in a paradigm specifically designed to probe both functions. We develop a physiologically plausible, explicit model of neural networks that maintain the currently active task rule in working memory and implement the decision process. We simplify the four-choice decision network to a nonlinear drift-diffusion process that we canonically derive from a generic winner-take-all network model. By fitting our model to the behavioral data of individual subjects, we can reproduce their full behavior in terms of decisions and reaction time distributions in baseline as well as distractor inhibition and switch conditions. Furthermore, we predict the individual hemodynamic response timecourse of the rule-representing network and localize it to a frontoparietal network including the inferior frontal junction area and the intraparietal sulcus, using functional magnetic resonance imaging. This refines the understanding of task-switch-related frontoparietal brain activity as reflecting attractor-like working memory representations of task rules. Finally, we estimate the subject-specific stability of the rule-representing attractor states in terms of the minimal action associated with a transition between different rule states in the phase-space of the fitted models. This stability measure correlates with switching-specific thalamocorticostriatal activation, i.e., with a system associated with flexible working memory updating and

  20. Stochastic Dynamics Underlying Cognitive Stability and Flexibility.

    PubMed

    Ueltzhöffer, Kai; Armbruster-Genç, Diana J N; Fiebach, Christian J

    2015-06-01

    Cognitive stability and flexibility are core functions in the successful pursuit of behavioral goals. While there is evidence for a common frontoparietal network underlying both functions and for a key role of dopamine in the modulation of flexible versus stable behavior, the exact neurocomputational mechanisms underlying those executive functions and their adaptation to environmental demands are still unclear. In this work we study the neurocomputational mechanisms underlying cue based task switching (flexibility) and distractor inhibition (stability) in a paradigm specifically designed to probe both functions. We develop a physiologically plausible, explicit model of neural networks that maintain the currently active task rule in working memory and implement the decision process. We simplify the four-choice decision network to a nonlinear drift-diffusion process that we canonically derive from a generic winner-take-all network model. By fitting our model to the behavioral data of individual subjects, we can reproduce their full behavior in terms of decisions and reaction time distributions in baseline as well as distractor inhibition and switch conditions. Furthermore, we predict the individual hemodynamic response timecourse of the rule-representing network and localize it to a frontoparietal network including the inferior frontal junction area and the intraparietal sulcus, using functional magnetic resonance imaging. This refines the understanding of task-switch-related frontoparietal brain activity as reflecting attractor-like working memory representations of task rules. Finally, we estimate the subject-specific stability of the rule-representing attractor states in terms of the minimal action associated with a transition between different rule states in the phase-space of the fitted models. This stability measure correlates with switching-specific thalamocorticostriatal activation, i.e., with a system associated with flexible working memory updating and

  1. iPSC-derived neurons as a higher-throughput readout for autism: Promises and pitfalls

    PubMed Central

    Prilutsky, Daria; Palmer, Nathan P.; Smedemark-Margulies, Niklas; Schlaeger, Thorsten M.; Margulies, David M.; Kohane, Isaac S.

    2014-01-01

    The elucidation of disease etiologies and establishment of robust, scalable, high-throughput screening assays for autism spectrum disorders (ASDs) have been impeded by both inaccessibility of disease-relevant neuronal tissue and the genetic heterogeneity of the disorder. Neuronal cells derived from induced pluripotent stem cells (iPSCs) from autism patients may circumvent these obstacles and serve as relevant cell models. To date, derived cells are characterized and screened by assessing their neuronal phenotypes. These characterizations are often etiology-specific or lack reproducibility and stability. In this manuscript, we present an overview of efforts to study iPSC-derived neurons as a model for autism, and we explore the plausibility of gene expression profiling as a reproducible and stable disease marker. PMID:24374161

  2. iPSC-derived neurons as a higher-throughput readout for autism: promises and pitfalls.

    PubMed

    Prilutsky, Daria; Palmer, Nathan P; Smedemark-Margulies, Niklas; Schlaeger, Thorsten M; Margulies, David M; Kohane, Isaac S

    2014-02-01

    The elucidation of disease etiologies and establishment of robust, scalable, high-throughput screening assays for autism spectrum disorders (ASDs) have been impeded by both inaccessibility of disease-relevant neuronal tissue and the genetic heterogeneity of the disorder. Neuronal cells derived from induced pluripotent stem cells (iPSCs) from autism patients may circumvent these obstacles and serve as relevant cell models. To date, derived cells are characterized and screened by assessing their neuronal phenotypes. These characterizations are often etiology-specific or lack reproducibility and stability. In this review, we present an overview of efforts to study iPSC-derived neurons as a model for autism, and we explore the plausibility of gene expression profiling as a reproducible and stable disease marker. PMID:24374161

  3. Temporal distribution of mantle-derived potassic rocks and carbonatites linked to stabilization of mantle lithosphere and redox states during subduction

    NASA Astrophysics Data System (ADS)

    Foley, S. F.

    2014-12-01

    Mantle-derived potassic igneous rocks and carbonatites first appear in the geological record in the late Archean, coinciding with major crust-forming events on most continents. The compositions of potassic rocks require sources including discrete ultramafic rocks with phlogopite and pyroxenes, whereas carbonatites and ultramafic lamprophyres (carbonate-rich potassic rocks) require oxidizing conditions in which carbonate is stable. The presence of these source rocks from this time is probably related to the stabilization of mantle lithosphere. If mantle lithosphere had not been stable for considerable periods of time, then melting would be restricted to peridotite, which is not a viable option for strongly potassic rocks. The phlogopite-rich source-rock assemblages that are necessary precursors for potassic melts could be introduced into the lithosphere by either subduction processes or by multiple stages of low-degree melting. Many modern examples involve subducted sedimentary material, which concentrates potassium by the stabilization of micas in subduction metamorphism. Subduction involves a great variety of redox states, but the bulk effect is the return of oxidized material from the surface into the mantle. However, we cannot apply uniformitarianism unthinkingly, because subduction processes at and before 2.7 Ga may have had different redox states. Before the Great Oxidation Event the distribution and abundances of geological formations such as banded iron formations, red beds, and uraninites indicate that geological reservoirs became gradually oxidized, preventing an earlier increase in atmospheric oxygen. This means that the function of the subduction process to oxidize the upper mantle by the return of oxidized rocks from the surface was much weaker in the early Earth. Early continental mantle lithosphere was, therefore, likely to accumulate carbon in reduced form, which would be more easily remobilized in melts through low-temperature redox melting much

  4. Self-Assembly of Phosphate Amphiphiles in Mixtures of Prebiotically Plausible Surfactants

    PubMed Central

    Albertsen, A.N.; Duffy, C.D.; Sutherland, J.D.

    2014-01-01

    Abstract The spontaneous formation of closed bilayer structures from prebiotically plausible amphiphiles is an essential requirement for the emergence of early cells on prebiotic Earth. The sources of amphiphiles could have been both endo- and exogenous (accretion of meteorite carbonaceous material or interstellar dust particles). Among all prebiotic possible amphiphile candidates, those containing phosphate are the least investigated species because their self-assembly occurs in a seemingly too narrow range of conditions. The self-assembly of simple phosphate amphiphiles should, however, be of great interest, as contemporary membranes predominantly contain phospholipids. In contrast to common expectations, we show that these amphiphiles can be easily synthesized under prebiotically plausible environmental conditions and can efficiently form bilayer structures in the presence of various co-surfactants across a large range of pH values. Vesiculation was even observed in crude reaction mixtures that contained 1-decanol as the amphiphile precursor. The two best co-surfactants promoted vesicle formation over the entire pH range in aqueous solutions. Expanding the pH range where bilayer membranes self-assemble and remain intact is a prerequisite for the emergence of early cell-like compartments and their preservation under fluctuating environmental conditions. These mixed bilayers also retained small charged solutes, such as dyes. These results demonstrate that alkyl phosphate amphiphiles might have played a significant role as early compartment building blocks. Key Words: Vesicles—Alkyl phosphate—Prebiotic synthesis—Amphiphile mixtures. Astrobiology 14, 462–472. PMID:24885934

  5. Particulate air pollution and increased mortality: Biological plausibility for causal relationship

    SciTech Connect

    Henderson, R.F.

    1995-02-01

    Recently, a number of epidemiological studies have concluded that ambient particulate exposure is associated with increased mortality and morbidity at PM concentrations well below those previously thought to affect human health. These studies have been conducted in several different geographical locations and have involved a range of populations. While the consistency of the findings and the presence of an apparent concentration response relationship provide a strong argument for causality, epidemiological studies can only conclude this based upon inference from statistical associations. The biological plausibility of a causal relationship between low concentrations of PM and daily mortality and morbidity rates is neither intuitively obvious nor expected based on past experimental studies on the toxicity of inhaled particles. Chronic toxicity from inhaled, poorly soluble particles has been observed based on the slow accumulation of large lung burdens of particles, not on small daily fluctuations in PM levels. Acute toxicity from inhaled particles is associated mainly with acidic particles and is observed at much higher concentrations than those observed in the epidemiology studies reporting an association between PM concentrations and morbidity/mortality. To approach the difficult problem of determining if the association between PM concentrations and daily morbidity and mortality is biologically plausible and causal, one must consider (1) the chemical and physical characteristics of the particles in the inhaled atmospheres, (2) the characteristics of the morbidity/mortality observed and the people who are affected, and (3) potential mechanisms that might link the two.

  6. Self-assembly of phosphate amphiphiles in mixtures of prebiotically plausible surfactants.

    PubMed

    Albertsen, A N; Duffy, C D; Sutherland, J D; Monnard, P-A

    2014-06-01

    The spontaneous formation of closed bilayer structures from prebiotically plausible amphiphiles is an essential requirement for the emergence of early cells on prebiotic Earth. The sources of amphiphiles could have been both endo- and exogenous (accretion of meteorite carbonaceous material or interstellar dust particles). Among all prebiotic possible amphiphile candidates, those containing phosphate are the least investigated species because their self-assembly occurs in a seemingly too narrow range of conditions. The self-assembly of simple phosphate amphiphiles should, however, be of great interest, as contemporary membranes predominantly contain phospholipids. In contrast to common expectations, we show that these amphiphiles can be easily synthesized under prebiotically plausible environmental conditions and can efficiently form bilayer structures in the presence of various co-surfactants across a large range of pH values. Vesiculation was even observed in crude reaction mixtures that contained 1-decanol as the amphiphile precursor. The two best co-surfactants promoted vesicle formation over the entire pH range in aqueous solutions. Expanding the pH range where bilayer membranes self-assemble and remain intact is a prerequisite for the emergence of early cell-like compartments and their preservation under fluctuating environmental conditions. These mixed bilayers also retained small charged solutes, such as dyes. These results demonstrate that alkyl phosphate amphiphiles might have played a significant role as early compartment building blocks. PMID:24885934

  7. Climate dynamics in deep time: Modeling the [snowball bifurcation] and assessing the plausibility of its occurrence

    NASA Astrophysics Data System (ADS)

    Peltier, W. R.; Tarasov, L.; Vettoretti, G.; Solheim, L. P.

    The apparently global scale glaciation events that occurred during the Neoproterozoic era, in the interval from 750 Ma to 550 Ma, represent a significant challenge to our understanding of climate system behavior. If these episodes of glaciation were truly of "snowball" type, with the continents covered by thick ice-sheets and the oceans entirely capped by sea ice, then special pleading is required to understand the Cambrian explosion of life that occurred subsequently. Detailed models of Neoproterozoic climate, however, suggest the plausibility of preference for "equatorial refugium" or "oasis" solutions in which significant regions of open water are able to persist at the equator. We describe further analyses of such solutions in this paper, using both simple EBM coupled ice sheet models and fully articulated atmosphere-ocean-sea ice coupled models of climate evolution. Recently published analyses of the dynamics of the Neoproterozoic carbon cycle, taken together with the predictions of the models discussed herein, are strongly supportive of the equatorial refugium solutions as the most plausible form of the Neoproterozoic cooling events.

  8. Morality Principles for Risk Modelling: Needs and Links with the Origins of Plausible Inference

    NASA Astrophysics Data System (ADS)

    Solana-Ortega, Alberto; Solana, Vicente

    2009-12-01

    In comparison with the foundations of probability calculus, the inescapable and controversial issue of how to assign probabilities has only recently become a matter of formal study. The introduction of information as a technical concept was a milestone, but the most promising entropic assignment methods still face unsolved difficulties, manifesting the incompleteness of plausible inference theory. In this paper we examine the situation faced by risk analysts in the critical field of extreme events modelling, where the former difficulties are especially visible, due to scarcity of observational data, the large impact of these phenomena and the obligation to assume professional responsibilities. To respond to the claim for a sound framework to deal with extremes, we propose a metafoundational approach to inference, based on a canon of extramathematical requirements. We highlight their strong moral content, and show how this emphasis in morality, far from being new, is connected with the historic origins of plausible inference. Special attention is paid to the contributions of Caramuel, a contemporary of Pascal, unfortunately ignored in the usual mathematical accounts of probability.

  9. Neural correlates of early-closure garden-path processing: Effects of prosody and plausibility.

    PubMed

    den Ouden, Dirk-Bart; Dickey, Michael Walsh; Anderson, Catherine; Christianson, Kiel

    2016-01-01

    Functional magnetic resonance imaging (fMRI) was used to investigate neural correlates of early-closure garden-path sentence processing and use of extrasyntactic information to resolve temporary syntactic ambiguities. Sixteen participants performed an auditory picture verification task on sentences presented with natural versus flat intonation. Stimuli included sentences in which the garden-path interpretation was plausible, implausible because of a late pragmatic cue, or implausible because of a semantic mismatch between an optionally transitive verb and the following noun. Natural sentence intonation was correlated with left-hemisphere temporal activation, but also with activation that suggests the allocation of more resources to interpretation when natural prosody is provided. Garden-path processing was associated with upregulation in bilateral inferior parietal and right-hemisphere dorsolateral prefrontal and inferior frontal cortex, while differences between the strength and type of plausibility cues were also reflected in activation patterns. Region of interest (ROI) analyses in regions associated with complex syntactic processing are consistent with a role for posterior temporal cortex supporting access to verb argument structure. Furthermore, ROI analyses within left-hemisphere inferior frontal gyrus suggest a division of labour, with the anterior-ventral part primarily involved in syntactic-semantic mismatch detection, the central part supporting structural reanalysis, and the posterior-dorsal part showing a general structural complexity effect. PMID:25801097

  10. The Sarrazin effect: the presence of absurd statements in conspiracy theories makes canonical information less plausible

    PubMed Central

    Raab, Marius Hans; Auer, Nikolas; Ortlieb, Stefan A.; Carbon, Claus-Christian

    2013-01-01

    Reptile prime ministers and flying Nazi saucers—extreme and sometimes off-wall conclusion are typical ingredients of conspiracy theories. While individual differences are a common research topic concerning conspiracy theories, the role of extreme statements in the process of acquiring and passing on conspiratorial stories has not been regarded in an experimental design so far. We identified six morphological components of conspiracy theories empirically. On the basis of these content categories a set of narrative elements for a 9/11 story was compiled. These elements varied systematically in terms of conspiratorial allegation, i.e., they contained official statements concerning the events of 9/11, statements alleging to a conspiracy limited in time and space as well as extreme statements indicating an all-encompassing cover-up. Using the method of narrative construction, 30 people were given a set of cards with these statements and asked to construct the course of events of 9/11 they deem most plausible. When extreme statements were present in the set, the resulting stories were more conspiratorial; the number of official statements included in the narrative dropped significantly, whereas the self-assessment of the story's plausibility did not differ between conditions. This indicates that blatant statements in a pool of information foster the synthesis of conspiracy theories on an individual level. By relating these findings to one of Germany's most successful (and controversial) non-fiction books, we refer to the real-world dangers of this effect. PMID:23882250

  11. A swarm intelligence framework for reconstructing gene networks: searching for biologically plausible architectures.

    PubMed

    Kentzoglanakis, Kyriakos; Poole, Matthew

    2012-01-01

    In this paper, we investigate the problem of reverse engineering the topology of gene regulatory networks from temporal gene expression data. We adopt a computational intelligence approach comprising swarm intelligence techniques, namely particle swarm optimization (PSO) and ant colony optimization (ACO). In addition, the recurrent neural network (RNN) formalism is employed for modeling the dynamical behavior of gene regulatory systems. More specifically, ACO is used for searching the discrete space of network architectures and PSO for searching the corresponding continuous space of RNN model parameters. We propose a novel solution construction process in the context of ACO for generating biologically plausible candidate architectures. The objective is to concentrate the search effort into areas of the structure space that contain architectures which are feasible in terms of their topological resemblance to real-world networks. The proposed framework is initially applied to the reconstruction of a small artificial network that has previously been studied in the context of gene network reverse engineering. Subsequently, we consider an artificial data set with added noise for reconstructing a subnetwork of the genetic interaction network of S. cerevisiae (yeast). Finally, the framework is applied to a real-world data set for reverse engineering the SOS response system of the bacterium Escherichia coli. Results demonstrate the relative advantage of utilizing problem-specific knowledge regarding biologically plausible structural properties of gene networks over conducting a problem-agnostic search in the vast space of network architectures. PMID:21576756

  12. The Sarrazin effect: the presence of absurd statements in conspiracy theories makes canonical information less plausible.

    PubMed

    Raab, Marius Hans; Auer, Nikolas; Ortlieb, Stefan A; Carbon, Claus-Christian

    2013-01-01

    Reptile prime ministers and flying Nazi saucers-extreme and sometimes off-wall conclusion are typical ingredients of conspiracy theories. While individual differences are a common research topic concerning conspiracy theories, the role of extreme statements in the process of acquiring and passing on conspiratorial stories has not been regarded in an experimental design so far. We identified six morphological components of conspiracy theories empirically. On the basis of these content categories a set of narrative elements for a 9/11 story was compiled. These elements varied systematically in terms of conspiratorial allegation, i.e., they contained official statements concerning the events of 9/11, statements alleging to a conspiracy limited in time and space as well as extreme statements indicating an all-encompassing cover-up. Using the method of narrative construction, 30 people were given a set of cards with these statements and asked to construct the course of events of 9/11 they deem most plausible. When extreme statements were present in the set, the resulting stories were more conspiratorial; the number of official statements included in the narrative dropped significantly, whereas the self-assessment of the story's plausibility did not differ between conditions. This indicates that blatant statements in a pool of information foster the synthesis of conspiracy theories on an individual level. By relating these findings to one of Germany's most successful (and controversial) non-fiction books, we refer to the real-world dangers of this effect. PMID:23882250

  13. Optimized Blanching Reduces the Host Cell Protein Content and Substantially Enhances the Recovery and Stability of Two Plant-Derived Malaria Vaccine Candidates

    PubMed Central

    Menzel, Stephan; Holland, Tanja; Boes, Alexander; Spiegel, Holger; Bolzenius, Johanna; Fischer, Rainer; Buyel, Johannes F.

    2016-01-01

    Plants provide an advantageous expression platform for biopharmaceutical proteins because of their low pathogen burden and potential for inexpensive, large-scale production. However, the purification of target proteins can be challenging due to issues with extraction, the removal of host cell proteins (HCPs), and low expression levels. The heat treatment of crude extracts can reduce the quantity of HCPs by precipitation thus increasing the purity of the target protein and streamlining downstream purification. In the overall context of downstream process (DSP) development for plant-derived malaria vaccine candidates, we applied a design-of-experiments approach to enhance HCP precipitation from Nicotiana benthamiana extracts generated after transient expression, using temperatures in the 20–80°C range, pH values of 3.0–8.0 and incubation times of 0–60 min. We also investigated the recovery of two protein-based malaria vaccine candidates under these conditions and determined their stability in the heat-treated extract while it was maintained at room temperature for 24 h. The heat precipitation of HCPs was also carried out by blanching intact plants in water or buffer prior to extraction in a blender. Our data show that all the heat precipitation methods reduced the amount of HCP in the crude plant extracts by more than 80%, simplifying the subsequent DSP steps. Furthermore, when the heat treatment was performed at 80°C rather than 65°C, both malaria vaccine candidates were more stable after extraction and the recovery of both proteins increased by more than 30%. PMID:26925077

  14. Bipolar tetraether lipids derived from thermoacidophilic archaeon Sulfolobus acidocaldarius for membrane stabilization of chlorin e6 based liposomes for photodynamic therapy.

    PubMed

    Mahmoud, Gihan; Jedelská, Jarmila; Strehlow, Boris; Bakowsky, Udo

    2015-09-01

    The initial burst release of water-soluble photosensitizers is one of the major problems encountered the development of controlled release formulations. In this study, the freely water soluble chlorin e6 (Ce6) was assembled with cationic lipid 1,2-dioleoyl-3-trimethylammonium-propane (DOTAP) to improve its loading efficiency in the liposomal bilayer. Tetraether lipids (TELs) derived from Sulfolobus acidocaldarius were added to DOTAP:Ce6 assembly in a concentration range of 2.5×10(-4)-1.6×10(-3)M to stabilize the membrane rigidity of the liposomes and to provide controlled release system. From the comparative spectroscopic experiments, it has been shown that the assembled DOTAP:Ce6 along with addition of TELs have improved the loading efficiency of Ce6 in TELs-liposomes and obviously modified the release profile of Ce6. The in vitro cell viability of Ce6 in mouse neuro-blastoma (Neuro-2a) and ovarian cell carcinoma (SK-OV-3) confirmed neglected dark cytotoxicity and presented potential photo-induced cytotoxicity with the effect was being more pronounced in Neuro 2a than in SK-OV-3. In-situ IV-injection of chick chorioallantoic membrane (CAM) showed hemorrhage and necrosis 30 min post irradiation at 1.8 mol% TELs (19.9J/cm(2)). Higher TELs of 2.2 and 3.7 mol% in particular demonstrated localized vascular destruction within the irradiated area. Our results suggest that TELs favored slower release rates of Ce6. This, in turn, tetraether lipids can be considered as a versatile class of lipids for photodynamic modality for destruction of cancer cells and tumor vasculature while sparing the quiescent ones. PMID:25936859

  15. Optimized Blanching Reduces the Host Cell Protein Content and Substantially Enhances the Recovery and Stability of Two Plant-Derived Malaria Vaccine Candidates.

    PubMed

    Menzel, Stephan; Holland, Tanja; Boes, Alexander; Spiegel, Holger; Bolzenius, Johanna; Fischer, Rainer; Buyel, Johannes F

    2016-01-01

    Plants provide an advantageous expression platform for biopharmaceutical proteins because of their low pathogen burden and potential for inexpensive, large-scale production. However, the purification of target proteins can be challenging due to issues with extraction, the removal of host cell proteins (HCPs), and low expression levels. The heat treatment of crude extracts can reduce the quantity of HCPs by precipitation thus increasing the purity of the target protein and streamlining downstream purification. In the overall context of downstream process (DSP) development for plant-derived malaria vaccine candidates, we applied a design-of-experiments approach to enhance HCP precipitation from Nicotiana benthamiana extracts generated after transient expression, using temperatures in the 20-80°C range, pH values of 3.0-8.0 and incubation times of 0-60 min. We also investigated the recovery of two protein-based malaria vaccine candidates under these conditions and determined their stability in the heat-treated extract while it was maintained at room temperature for 24 h. The heat precipitation of HCPs was also carried out by blanching intact plants in water or buffer prior to extraction in a blender. Our data show that all the heat precipitation methods reduced the amount of HCP in the crude plant extracts by more than 80%, simplifying the subsequent DSP steps. Furthermore, when the heat treatment was performed at 80°C rather than 65°C, both malaria vaccine candidates were more stable after extraction and the recovery of both proteins increased by more than 30%. PMID:26925077

  16. In Silico Structure Prediction of Human Fatty Acid Synthase–Dehydratase: A Plausible Model for Understanding Active Site Interactions

    PubMed Central

    John, Arun; Umashankar, Vetrivel; Samdani, A.; Sangeetha, Manoharan; Krishnakumar, Subramanian; Deepa, Perinkulam Ravi

    2016-01-01

    Fatty acid synthase (FASN, UniProt ID: P49327) is a multienzyme dimer complex that plays a critical role in lipogenesis. Consequently, this lipogenic enzyme has gained tremendous biomedical importance. The role of FASN and its inhibition is being extensively researched in several clinical conditions, such as cancers, obesity, and diabetes. X-ray crystallographic structures of some of its domains, such as β-ketoacyl synthase, acetyl transacylase, malonyl transacylase, enoyl reductase, β-ketoacyl reductase, and thioesterase, (TE) are already reported. Here, we have attempted an in silico elucidation of the uncrystallized dehydratase (DH) catalytic domain of human FASN. This theoretical model for DH domain was predicted using comparative modeling methods. Different stand-alone tools and servers were used to validate and check the reliability of the predicted models, which suggested it to be a highly plausible model. The stereochemical analysis showed 92.0% residues in favorable region of Ramachandran plot. The initial physiological substrate β-hydroxybutyryl group was docked into active site of DH domain using Glide. The molecular dynamics simulations carried out for 20 ns in apo and holo states indicated the stability and accuracy of the predicted structure in solvated condition. The predicted model provided useful biochemical insights into the substrate–active site binding mechanisms. This model was then used for identifying potential FASN inhibitors using high-throughput virtual screening of the National Cancer Institute database of chemical ligands. The inhibitory efficacy of the top hit ligands was validated by performing molecular dynamics simulation for 20 ns, where in the ligand NSC71039 exhibited good enzyme inhibition characteristics and exhibited dose-dependent anticancer cytotoxicity in retinoblastoma cancer cells in vitro. PMID:27559295

  17. In Silico Structure Prediction of Human Fatty Acid Synthase-Dehydratase: A Plausible Model for Understanding Active Site Interactions.

    PubMed

    John, Arun; Umashankar, Vetrivel; Samdani, A; Sangeetha, Manoharan; Krishnakumar, Subramanian; Deepa, Perinkulam Ravi

    2016-01-01

    Fatty acid synthase (FASN, UniProt ID: P49327) is a multienzyme dimer complex that plays a critical role in lipogenesis. Consequently, this lipogenic enzyme has gained tremendous biomedical importance. The role of FASN and its inhibition is being extensively researched in several clinical conditions, such as cancers, obesity, and diabetes. X-ray crystallographic structures of some of its domains, such as β-ketoacyl synthase, acetyl transacylase, malonyl transacylase, enoyl reductase, β-ketoacyl reductase, and thioesterase, (TE) are already reported. Here, we have attempted an in silico elucidation of the uncrystallized dehydratase (DH) catalytic domain of human FASN. This theoretical model for DH domain was predicted using comparative modeling methods. Different stand-alone tools and servers were used to validate and check the reliability of the predicted models, which suggested it to be a highly plausible model. The stereochemical analysis showed 92.0% residues in favorable region of Ramachandran plot. The initial physiological substrate β-hydroxybutyryl group was docked into active site of DH domain using Glide. The molecular dynamics simulations carried out for 20 ns in apo and holo states indicated the stability and accuracy of the predicted structure in solvated condition. The predicted model provided useful biochemical insights into the substrate-active site binding mechanisms. This model was then used for identifying potential FASN inhibitors using high-throughput virtual screening of the National Cancer Institute database of chemical ligands. The inhibitory efficacy of the top hit ligands was validated by performing molecular dynamics simulation for 20 ns, where in the ligand NSC71039 exhibited good enzyme inhibition characteristics and exhibited dose-dependent anticancer cytotoxicity in retinoblastoma cancer cells in vitro. PMID:27559295

  18. Low-Speed Investigation of the Effects of Frequency and Amplitude of Oscillation in Sideslip on the Lateral Stability Derivatives of a 60 deg Delta Wing, a 45 deg Sweptback Wing and an Unswept Wing

    NASA Technical Reports Server (NTRS)

    Lichtenstein, Jacob H.; Williams, James L.

    1961-01-01

    A low-speed investigation has been conducted in the Langley stability tunnel to study the effects of frequency and amplitude of sideslipping motion on the lateral stability derivatives of a 60 deg. delta wing, a 45 deg. sweptback wing, and an unswept wing. The investigation was made for values of the reduced-frequency parameter of 0.066 and 0.218 and for a range of amplitudes from +/- 2 to +/- 6 deg. The results of the investigation indicated that increasing the frequency of the oscillation generally produced an appreciable change in magnitude of the lateral oscillatory stability derivatives in the higher angle-of-attack range. This effect was greatest for the 60 deg. delta wing and smallest for the unswept wing and generally resulted in a more linear variation of these derivatives with angle of attack. For the relatively high frequency at which the amplitude was varied, there appeared to be little effect on the measured derivatives as a result of the change in amplitude of the oscillation.

  19. Theoretical and Analog Studies of the Effects of Nonlinear Stability Derivatives on the Longitudinal Motions of an Aircraft in Response to Step Control Deflections and to the Influence of Proportional Automatic Control

    NASA Technical Reports Server (NTRS)

    Curfman, Howard J , Jr

    1955-01-01

    Through theoretical and analog results the effects of two nonlinear stability derivatives on the longitudinal motions of an aircraft have been investigated. Nonlinear functions of pitching-moment and lift coefficients with angle of attack were considered. Analog results of aircraft motions in response to step elevator deflections and to the action of the proportional control systems are presented. The occurrence of continuous hunting oscillations was predicted and demonstrated for the attitude stabilization system with proportional control for certain nonlinear pitching-moment variations and autopilot adjustments.

  20. A plausible mechanism for the antimalarial activity of artemisinin: A computational approach

    PubMed Central

    Shandilya, Ashutosh; Chacko, Sajeev; Jayaram, B.; Ghosh, Indira

    2013-01-01

    Artemisinin constitutes the frontline treatment to aid rapid clearance of parasitaemia and quick resolution of malarial symptoms. However, the widespread promiscuity about its mechanism of action is baffling. There is no consensus about the biochemical target of artemisinin but recent studies implicate haem and PfATP6 (a calcium pump). We investigated the role of iron and artemisinin on PfATP6, in search of a plausible mechanism of action, via density functional theory calculations, docking and molecular dynamics simulations. Results suggest that artemisinin gets activated by iron which in turn inhibits PfATP6 by closing the phosphorylation, nucleotide binding and actuator domains leading to loss of function of PfATP6 of the parasite and its death. The mechanism elucidated here should help in the design of novel antimalarials. PMID:23985481

  1. Spontaneous formation and base pairing of plausible prebiotic nucleotides in water.

    PubMed

    Cafferty, Brian J; Fialho, David M; Khanam, Jaheda; Krishnamurthy, Ramanarayanan; Hud, Nicholas V

    2016-01-01

    The RNA World hypothesis presupposes that abiotic reactions originally produced nucleotides, the monomers of RNA and universal constituents of metabolism. However, compatible prebiotic reactions for the synthesis of complementary (that is, base pairing) nucleotides and mechanisms for their mutual selection within a complex chemical environment have not been reported. Here we show that two plausible prebiotic heterocycles, melamine and barbituric acid, form glycosidic linkages with ribose and ribose-5-phosphate in water to produce nucleosides and nucleotides in good yields. Even without purification, these nucleotides base pair in aqueous solution to create linear supramolecular assemblies containing thousands of ordered nucleotides. Nucleotide anomerization and supramolecular assemblies favour the biologically relevant β-anomer form of these ribonucleotides, revealing abiotic mechanisms by which nucleotide structure and configuration could have been originally favoured. These findings indicate that nucleotide formation and selection may have been robust processes on the prebiotic Earth, if other nucleobases preceded those of extant life. PMID:27108699

  2. Reciprocity-Based Reasons for Benefiting Research Participants: Most Fail, the Most Plausible is Problematic

    PubMed Central

    Sofaer, Neema

    2014-01-01

    A common reason for giving research participants post-trial access (PTA) to the trial intervention appeals to reciprocity, the principle, stated most generally, that if one person benefits a second, the second should reciprocate: benefit the first in return. Many authors consider it obvious that reciprocity supports PTA. Yet their reciprocity principles differ, with many authors apparently unaware of alternative versions. This article is the first to gather the range of reciprocity principles. It finds that: (1) most are false. (2) The most plausible principle, which is also problematic, applies only when participants experience significant net risks or burdens. (3) Seldom does reciprocity support PTA for participants or give researchers stronger reason to benefit participants than equally needy non-participants. (4) Reciprocity fails to explain the common view that it is bad when participants in a successful trial have benefited from the trial intervention but lack PTA to it. PMID:24602060

  3. Spontaneous formation and base pairing of plausible prebiotic nucleotides in water

    PubMed Central

    Cafferty, Brian J.; Fialho, David M.; Khanam, Jaheda; Krishnamurthy, Ramanarayanan; Hud, Nicholas V.

    2016-01-01

    The RNA World hypothesis presupposes that abiotic reactions originally produced nucleotides, the monomers of RNA and universal constituents of metabolism. However, compatible prebiotic reactions for the synthesis of complementary (that is, base pairing) nucleotides and mechanisms for their mutual selection within a complex chemical environment have not been reported. Here we show that two plausible prebiotic heterocycles, melamine and barbituric acid, form glycosidic linkages with ribose and ribose-5-phosphate in water to produce nucleosides and nucleotides in good yields. Even without purification, these nucleotides base pair in aqueous solution to create linear supramolecular assemblies containing thousands of ordered nucleotides. Nucleotide anomerization and supramolecular assemblies favour the biologically relevant β-anomer form of these ribonucleotides, revealing abiotic mechanisms by which nucleotide structure and configuration could have been originally favoured. These findings indicate that nucleotide formation and selection may have been robust processes on the prebiotic Earth, if other nucleobases preceded those of extant life. PMID:27108699

  4. Plausible authentication of manuka honey and related products by measuring leptosperin with methyl syringate.

    PubMed

    Kato, Yoji; Fujinaka, Rie; Ishisaka, Akari; Nitta, Yoko; Kitamoto, Noritoshi; Takimoto, Yosuke

    2014-07-01

    Manuka honey, obtained from Leptospermum scoparium flowers in New Zealand, has strong antibacterial properties. In this study, plausible authentication of the manuka honey was inspected by measuring leptosperin, methyl syringate 4-O-β-D-gentiobiose, along with methyl syringate. Despite a gradual decrease in methyl syringate content over 30 days at 50 °C, even at moderate 37 °C, leptosperin remained stable. A considerable correlation between nonperoxide antibacterial activity and leptosperin content was observed in 20 certified manuka honey samples. Leptosperin and methyl syringate in manuka honey and related products were analyzed using HPLC connected with mass spectrometry. One noncertified brand displayed significant variations in the leptosperin and methyl syringate contents between two samples obtained from different regions. Therefore, certification is clearly required to protect consumers from disguised and/or low-quality honey. Because leptosperin is stable during storage and specific to manuka honey, its measurement may be applicable for manuka honey authentication. PMID:24941263

  5. Quantum theory as plausible reasoning applied to data obtained by robust experiments.

    PubMed

    De Raedt, H; Katsnelson, M I; Michielsen, K

    2016-05-28

    We review recent work that employs the framework of logical inference to establish a bridge between data gathered through experiments and their objective description in terms of human-made concepts. It is shown that logical inference applied to experiments for which the observed events are independent and for which the frequency distribution of these events is robust with respect to small changes of the conditions under which the experiments are carried out yields, without introducing any concept of quantum theory, the quantum theoretical description in terms of the Schrödinger or the Pauli equation, the Stern-Gerlach or Einstein-Podolsky-Rosen-Bohm experiments. The extraordinary descriptive power of quantum theory then follows from the fact that it is plausible reasoning, that is common sense, applied to reproducible and robust experimental data. PMID:27091169

  6. Oxidation of cefazolin by potassium permanganate: Transformation products and plausible pathways.

    PubMed

    Li, Liping; Wei, Dongbin; Wei, Guohua; Du, Yuguo

    2016-04-01

    Cefazolin was demonstrated to exert high reactivity toward permanganate (Mn(VII)), a common oxidant in water pre-oxidation treatment. In this study, five transformation products were found to be classified into three categories according to the contained characteristic functional groups: three (di-)sulfoxide products, one sulfone product and one di-ketone product. Products analyses showed that two kinds of reactions including oxidation of thioether and the cleavage of unsaturated CC double bond occurred during transformation of cefazolin by Mn(VII). Subsequently, the plausible transformation pathways under different pH conditions were proposed based on the identified products and chemical reaction principles. More importantly, the simulation with real surface water matrix indicated that the proposed transformation pathways of cefazolin could be replayed in real water treatment practices. PMID:26872071

  7. A Neurally Plausible Parallel Distributed Processing Model of Event-Related Potential Word Reading Data

    PubMed Central

    Laszlo, Sarah; Plaut, David C.

    2011-01-01

    The Parallel Distributed Processing (PDP) framework has significant potential for producing models of cognitive tasks that approximate how the brain performs the same tasks. To date, however, there has been relatively little contact between PDP modeling and data from cognitive neuroscience. In an attempt to advance the relationship between explicit, computational models and physiological data collected during the performance of cognitive tasks, we developed a PDP model of visual word recognition which simulates key results from the ERP reading literature, while simultaneously being able to successfully perform lexical decision—a benchmark task for reading models. Simulations reveal that the model’s success depends on the implementation of several neurally plausible features in its architecture which are sufficiently domain-general to be relevant to cognitive modeling more generally. PMID:21945392

  8. A neurally plausible parallel distributed processing model of event-related potential word reading data.

    PubMed

    Laszlo, Sarah; Plaut, David C

    2012-03-01

    The Parallel Distributed Processing (PDP) framework has significant potential for producing models of cognitive tasks that approximate how the brain performs the same tasks. To date, however, there has been relatively little contact between PDP modeling and data from cognitive neuroscience. In an attempt to advance the relationship between explicit, computational models and physiological data collected during the performance of cognitive tasks, we developed a PDP model of visual word recognition which simulates key results from the ERP reading literature, while simultaneously being able to successfully perform lexical decision-a benchmark task for reading models. Simulations reveal that the model's success depends on the implementation of several neurally plausible features in its architecture which are sufficiently domain-general to be relevant to cognitive modeling more generally. PMID:21945392

  9. A simple plausible path from QCD to successful prediction of e+e- → hadronization data

    NASA Astrophysics Data System (ADS)

    Chun, SeBong; Buchanan, Charles

    1998-01-01

    We find a remarkably simple path emerging which begins with QCD and ends with rather accurate predictions of detailed hadronic production data (flavors, distributions, correlations) in electron-positron interactions, the cleanest situation in which to study such hadronization phenomena. This path involves relatively few significant parameters and many plausible physical ideas. The predictions are especially clean (only two ‘ natural’ parameters and no ‘ ad hoc’ ones) and accurate for the production of various flavored light-quark mesons, the most fundamental and elementary tests of colorfield behavior. This appears to improve our understanding of the physics of the meson formation process and forms a foundation for further development of other more complex areas (e.g., baryon production, PT effects) which we currently predict adequately, but where we must employ a small number of ‘ ad hoc’ parameters. The physics of our approach resembles that of a relativistic string and, in fact, historically is a spin-off from the very successful Lund modeling. However, our model's conceptual basis represents a paradigm shift away from emphasizing intermediate stages in an event and toward an emphasis on the total transition from the e+e- initial state to the entire set of final state hadrons. The model's central feature is a simple Event Weight Function incorporating a QCD-motivated space-time area law which, on the one hand, leads with very few assumptions to predictions agreeing remarkably well with e+e- → hadronization data, and, on the other hand, can also be plausibly related to strong-coupling soft QCD and can form a ‘ target’ for non-perturbative calculational approaches. Our approach avoids most of the parameters employed by traditional relativistic string models.

  10. Establishing medical plausibility in the context of orphan medicines designation in the European Union.

    PubMed

    Tsigkos, Stelios; Mariz, Segundo; Llinares, Jordi; Fregonese, Laura; Aarum, Stiina; Naumann-Winter, Frauke; Frauke, Naumann-Winter; Westermark, Kerstin; Sepodes, Bruno

    2014-01-01

    In the European Union, sponsors have the responsibility to demonstrate the "intention to diagnose, prevent or treat" a serious and rare condition before the Committee of Orphan Medicinal Products (COMP), for a medicinal product to meet the criteria for Orphan Designation. This requirement is commonly referred to as "medical plausibility" and the justification of this intention is assessed on the merits of each application by the COMP, which deliberates over the scientific evaluation of the evidence submitted. The scientific assessment of the applications for orphan designation by the Committee is based on the review of non-clinical (such as in vitro and in vivo) and/or clinical data submitted by the sponsor. Several challenges regarding the evidence provided emerge when the sponsor is applying for a designation at an early stage of development. Herein we discuss specific examples from the experience of the COMP, in order to elaborate on the type and level of evidence generally considered necessary for the purpose of justification of the intention to treat an orphan condition. Importantly, it is pointed out that bridging of data from other products, irrespectively of how comparable they may be, or from settings not directly associated with the condition as applied for designation, is by and large not a successful exercise and may only be exceptionally considered. It is further exemplified that, as reflected in the updated 'Guideline on the format and context of the applications for designation' and the guidance document 'Recommendation on elements required to support the medical plausibility and the assumption of significant benefit for an orphan designation' available on the EMA website, the sponsor should provide data with the specific product as applied for in specific models of the condition or in patients affected by the same condition subject of each application. PMID:25475155

  11. Plasmalogen enrichment in exosomes secreted by a nematode parasite versus those derived from its mouse host: implications for exosome stability and biology.

    PubMed

    Simbari, Fabio; McCaskill, Jana; Coakley, Gillian; Millar, Marissa; Maizels, Rick M; Fabriás, Gemma; Casas, Josefina; Buck, Amy H

    2016-01-01

    Extracellular vesicles (EVs) mediate communication between cells and organisms across all 3 kingdoms of life. Several reports have demonstrated that EVs can transfer molecules between phylogenetically diverse species and can be used by parasites to alter the properties of the host environment. Whilst the concept of vesicle secretion and uptake is broad reaching, the molecular composition of these complexes is expected to be diverse based on the physiology and environmental niche of different organisms. Exosomes are one class of EVs originally defined based on their endocytic origin, as these derive from multivesicular bodies that then fuse with the plasma membrane releasing them into the extracellular environment. The term exosome has also been used to describe any small EVs recovered by high-speed ultracentrifugation, irrespective of origin since this is not always well characterized. Here, we use comparative global lipidomic analysis to examine the composition of EVs, which we term exosomes, that are secreted by the gastrointestinal nematode, Heligmosomoides polygyrus, in relation to exosomes secreted by cells of its murine host. Ultra-performance liquid chromatography - tandem mass spectrometry (UPLC-MS/MS) analysis reveals a 9- to 62-fold enrichment of plasmalogens, as well as other classes of ether glycerophospholipids, along with a relative lack of cholesterol and sphingomyelin (SM) in the nematode exosomes compared with those secreted by murine cells. Biophysical analyses of the membrane dynamics of these exosomes demonstrate increased rigidity in those from the nematode, and parallel studies with synthetic vesicles support a role of plasmalogens in stabilizing the membrane structure. These results suggest that nematodes can maintain exosome membrane structure and integrity through increased plasmalogens, compensating for diminished levels of other lipids, including cholesterol and SM. This work also illuminates the prevalence of plasmalogens in some EVs

  12. Plasmalogen enrichment in exosomes secreted by a nematode parasite versus those derived from its mouse host: implications for exosome stability and biology

    PubMed Central

    Simbari, Fabio; McCaskill, Jana; Coakley, Gillian; Millar, Marissa; Maizels, Rick M.; Fabriás, Gemma; Casas, Josefina; Buck, Amy H.

    2016-01-01

    Extracellular vesicles (EVs) mediate communication between cells and organisms across all 3 kingdoms of life. Several reports have demonstrated that EVs can transfer molecules between phylogenetically diverse species and can be used by parasites to alter the properties of the host environment. Whilst the concept of vesicle secretion and uptake is broad reaching, the molecular composition of these complexes is expected to be diverse based on the physiology and environmental niche of different organisms. Exosomes are one class of EVs originally defined based on their endocytic origin, as these derive from multivesicular bodies that then fuse with the plasma membrane releasing them into the extracellular environment. The term exosome has also been used to describe any small EVs recovered by high-speed ultracentrifugation, irrespective of origin since this is not always well characterized. Here, we use comparative global lipidomic analysis to examine the composition of EVs, which we term exosomes, that are secreted by the gastrointestinal nematode, Heligmosomoides polygyrus, in relation to exosomes secreted by cells of its murine host. Ultra-performance liquid chromatography – tandem mass spectrometry (UPLC-MS/MS) analysis reveals a 9- to 62-fold enrichment of plasmalogens, as well as other classes of ether glycerophospholipids, along with a relative lack of cholesterol and sphingomyelin (SM) in the nematode exosomes compared with those secreted by murine cells. Biophysical analyses of the membrane dynamics of these exosomes demonstrate increased rigidity in those from the nematode, and parallel studies with synthetic vesicles support a role of plasmalogens in stabilizing the membrane structure. These results suggest that nematodes can maintain exosome membrane structure and integrity through increased plasmalogens, compensating for diminished levels of other lipids, including cholesterol and SM. This work also illuminates the prevalence of plasmalogens in some EVs

  13. Biochemical stability of organic matter in soils amended with organic slow N-release fertilizer derived from charred plant residues and ammonoxidized lignin

    NASA Astrophysics Data System (ADS)

    Knicker, Heike; de la Rosa, José Maria; López Martín, María; Clemente Barragan, Reyes; Liebner, Falk

    2013-04-01

    As an important plant nutrient, N that has been removed from the soil by plant growth is replaced mainly by the use of synthetic fertilizers. Although this practice has dramatically increased food production, the unintended costs to the environment and human health due to surplus and inefficient application have also been substantial. Major losses of N to the environment can be minimized if "sustainable" agricultural practices are combined with reasonable fertilization. The latter can be achieved by applying slow N-release fertilizers. Here, the N is incorporated into an organic matrix, which after its amendment to soils, slowly decompose, allowing the liberation of the nutrient. Deriving from organic waste, such an amendment helps to efficiently recycle resources and increases the C sequestration potential of soils. However, in order to turn this approach into a successful strategy, the material has to be bioavailable but still sufficiently recalcitrant to ensure slow and controlled N-release. In the present study, we tested potential slow N-release fertilizers recycled from organic waste for their biochemical stability in soils. They comprised N-rich charred grass residues and N-lignin derived from waste of the pulp and paper industry and enriched in N by ammonoxidation. The substrates were mixed with soil of an Histic Humaquept and subsequently subjected to microbial degradation at 28°C in a Respicond IV Apparatus for 10 weeks. Additionally, soil material without organic amendment and soils mixed with lignin or charcoal both with and without KNO3 were included into the experiment. During the degradation experiment the CO2 production was determined on an hourly base. The degradation rate constants and the mean residence times were calculated using a double exponential decay model (pools with fast and slow turnover). Alterations of the chemical composition of the organic matter during degradation were studied by solid-state 13C NMR spectroscopy. First results

  14. Structural Stabilities of β-Ti Alloys Studied Using a New Mo Equivalent Derived from [ β/( α + β)] Phase-Boundary Slopes

    NASA Astrophysics Data System (ADS)

    Wang, Qing; Dong, Chuang; Liaw, Peter K.

    2015-08-01

    Structural stabilities of β-Ti alloys are generally investigated by an empirical Mo equivalent, which quantifies the stability contribution of each alloying element, M, in comparison to that of the major β-Ti stabilizer, Mo. In the present work, a new Mo equivalent (Moeq)Q is proposed, which uses the slopes of the boundary lines between the β and ( α + β) phase zones in binary Ti-M phase diagrams. This (Moeq)Q reflects a simple fact that the β-Ti stability is enhanced, when the β phase zone is enlarged by a β-Ti stabilizer. It is expressed as (Moeq)Q = 1.0 Mo + 0.74 V + 1.01 W + 0.23 Nb + 0.30 Ta + 1.23 Fe + 1.10 Cr + 1.09 Cu + 1.67 Ni + 1.81 Co + 1.42 Mn + 0.38 Sn + 0.34 Zr + 0.99 Si - 0.57 Al (at. pct), where the equivalent coefficient of each element is the slope ratio of the [ β/( α + β)] boundary line of the binary Ti-M phase diagram to that of the Ti-Mo. This (Moeq)Q is shown to reliably characterize the critical stability limit of multi-component β-Ti alloys with low Young's moduli, where the critical lower limit for β stabilization is (Moeq)Q = 6.25 at. pct or 11.8 wt pct Mo.

  15. Wind-Tunnel Investigation at Subsonic and Supersonic Speeds of the Static and Dynamic Stability Derivatives of an Airplane Model with an Unswept Wing and a High Horizontal Tail

    NASA Technical Reports Server (NTRS)

    Lessing, Henry C.; Butler, James K.

    1959-01-01

    Results are presented of a wind-tunnel investigation to evaluate the static and dynamic stability derivatives of a model with a low-aspect-ratio unswept wing and a high horizontal tail. In addition to results for the complete model, results were also obtained of the body alone, body and wing, and body and tail. Data were obtained in the Mach number range from 0.65 to 2.2, at a Reynolds number of 2 million based on the wing mean aerodynamic chord. The angle-of-attack range for most of the data was -11.5 deg to 18 deg. A limited amount of data was obtained with fixed transition. A correspondence between the damping in pitch and the static stability, previously noted in other investigations, was also observed in the present results. The effect observed was that a decrease (or increase) in the static stability was accompanied by an increase (or decrease) in the damping in pitch. A similar correspondence was observed between the damping in yaw and the static-directional stability. Results from similar tests of the same model configuration in two other facilities over different speed ranges are presented for comparison. It was found that most of the results from the three investigations correlated reasonably well. Estimates of the rotary derivatives were made using available procedures. Comparison with the experimental results indicates the need for development of more precise estimation procedures.

  16. Why a high statistical performance cannot be equated with a high plausibility of landslide susceptibility maps

    NASA Astrophysics Data System (ADS)

    Steger, Stefan; Brenning, Alexander; Bell, Rainer; Petschko, Helene; Glade, Thomas

    2015-04-01

    Statistical landslide susceptibility maps express a relative estimate of where landslides are more likely to occur in the future due to a set of geo-environmental conditions. Their predictive capability is regularly deduced by interpreting threshold independent performance measures like the area under the receiver operating characteristic curve (AUROC). These quantitative estimates frequently serve as a decision tool to favour a certain classifier over another and/or to select a suitable combination of predictors. Literature exposes that many authors consider their final maps as a valuable instrument for spatial planners and decision makers. However, most often the susceptibility maps are selected by solely interpreting such quantitative estimates. We assume that a high statistical quality is necessary but not sufficient in order to produce plausible landslide susceptibility maps. This assumption was tested by quantitatively and qualitatively validating 16 susceptibility models for a study area (1354 km²) located in Lower Austria. The models were generated by applying two statistical and two machine learning classifiers separately for two landslide inventories and two sets of predictors. Quantitative validation was conducted by estimating the AUROC with non spatial hold-out validation and a repeated spatial cross validation technique. The spatial differentiation of the final maps was evaluated at different scales by interpreting semivariograms. Maps of the location of major variations illustrate the spatial structure of the final susceptibility maps and allowed to deduce the most influential predictors and predictor classes. According to the hold-out validation, all 16 susceptibility models performed similarly well. However, spatial cross validation revealed considerable differences between models generated by different landslide inventories. Semivariograms exposed that the predicted landslide susceptibility pattern differs substantially between maps generated by

  17. On the biological plausibility of grandmother cells: implications for neural network theories in psychology and neuroscience.

    PubMed

    Bowers, Jeffrey S

    2009-01-01

    A fundamental claim associated with parallel distributed processing (PDP) theories of cognition is that knowledge is coded in a distributed manner in mind and brain. This approach rejects the claim that knowledge is coded in a localist fashion, with words, objects, and simple concepts (e.g. "dog"), that is, coded with their own dedicated representations. One of the putative advantages of this approach is that the theories are biologically plausible. Indeed, advocates of the PDP approach often highlight the close parallels between distributed representations learned in connectionist models and neural coding in brain and often dismiss localist (grandmother cell) theories as biologically implausible. The author reviews a range a data that strongly challenge this claim and shows that localist models provide a better account of single-cell recording studies. The author also contrast local and alternative distributed coding schemes (sparse and coarse coding) and argues that common rejection of grandmother cell theories in neuroscience is due to a misunderstanding about how localist models behave. The author concludes that the localist representations embedded in theories of perception and cognition are consistent with neuroscience; biology only calls into question the distributed representations often learned in PDP models. PMID:19159155

  18. Event-based Plausibility Immediately Influences On-line Language Comprehension

    PubMed Central

    Matsuki, Kazunaga; Chow, Tracy; Hare, Mary; Elman, Jeffrey L.; Scheepers, Christoph; McRae, Ken

    2011-01-01

    In some theories of sentence comprehension, linguistically-relevant lexical knowledge such as selectional restrictions is privileged in terms of the time-course of its access and influence. We examined whether event knowledge computed by combining multiple concepts can rapidly influence language understanding even in the absence of selectional restriction violations. Specifically, we investigated whether instruments can combine with actions to influence comprehension of ensuing patients. Instrument-verb-patient triplets were created in a norming study designed to tap directly into event knowledge. In self-paced reading (Experiment 1), participants were faster to read patient nouns such as hair when they were typical of the instrument-action pair (Donna used the shampoo to wash vs. the hose to wash). Experiment 2 showed that these results were not due to direct instrument-patient relations. Experiment 3 replicated Experiment 1 using eyetracking, with effects of event typicality observed in first fixation and gaze durations on the patient noun. This research demonstrates that conceptual event-based expectations are computed and used rapidly and dynamically during on-line language comprehension. We discuss relationships among plausibility and predictability, as well as their implications. We conclude that selectional restrictions may be best considered as event-based conceptual knowledge, rather than lexical-grammatical knowledge. PMID:21517222

  19. A plausible mechanism of biosorption in dual symbioses by vesicular-arbuscular mycorrhizal in plants.

    PubMed

    Azmat, Rafia; Hamid, Neelofer

    2015-03-01

    Dual symbioses of vesicular-arbuscular mycorrhizal (VAM) fungi with growth of Momordica charantia were elucidated in terms of plausible mechanism of biosorption in this article. The experiment was conducted in green house and mixed inoculum of the VAM fungi was used in the three replicates. Results demonstrated that the starch contents were the main source of C for the VAM to builds their hyphae. The increased plant height and leaves surface area were explained in relation with an increase in the photosynthetic rates to produce rapid sugar contents for the survival of plants. A decreased in protein, and amino acid contents and increased proline and protease activity in VAM plants suggested that these contents were the main bio-indicators of the plants under biotic stress. The decline in protein may be due to the degradation of these contents, which later on converted into dextrose where it can easily be absorbed by for the period of symbioses. A mechanism of C chemisorption in relation with physiology and morphology of plant was discussed. PMID:25730809

  20. Event-based plausibility immediately influences on-line language comprehension.

    PubMed

    Matsuki, Kazunaga; Chow, Tracy; Hare, Mary; Elman, Jeffrey L; Scheepers, Christoph; McRae, Ken

    2011-07-01

    In some theories of sentence comprehension, linguistically relevant lexical knowledge, such as selectional restrictions, is privileged in terms of the time-course of its access and influence. We examined whether event knowledge computed by combining multiple concepts can rapidly influence language understanding even in the absence of selectional restriction violations. Specifically, we investigated whether instruments can combine with actions to influence comprehension of ensuing patients of (as in Rayner, Warren, Juhuasz, & Liversedge, 2004; Warren & McConnell, 2007). Instrument-verb-patient triplets were created in a norming study designed to tap directly into event knowledge. In self-paced reading (Experiment 1), participants were faster to read patient nouns, such as hair, when they were typical of the instrument-action pair (Donna used the shampoo to wash vs. the hose to wash). Experiment 2 showed that these results were not due to direct instrument-patient relations. Experiment 3 replicated Experiment 1 using eyetracking, with effects of event typicality observed in first fixation and gaze durations on the patient noun. This research demonstrates that conceptual event-based expectations are computed and used rapidly and dynamically during on-line language comprehension. We discuss relationships among plausibility and predictability, as well as their implications. We conclude that selectional restrictions may be best considered as event-based conceptual knowledge rather than lexical-grammatical knowledge. PMID:21517222

  1. Medical concepts related to individual risk are better explained with "plausibility" rather than "probability"

    PubMed Central

    Grossi, Enzo

    2005-01-01

    Background The concept of risk has pervaded medical literature in the last decades and has become a familiar topic, and the concept of probability, linked to binary logic approach, is commonly applied in epidemiology and clinical medicine. The application of probability theory to groups of individuals is quite straightforward but can pose communication challenges at individual level. Few articles by the way have tried to focus the concept of "risk" at the individual subject level rather than at population level. Discussion The author has reviewed the conceptual framework which has led to the use of probability theory in the medical field in a time when the principal causes of death were represented by acute disease often of infective origin. In the present scenario, in which chronic degenerative disease dominate and there are smooth transitions between health and disease the use of fuzzy logic rather than binary logic would be more appropriate. The use of fuzzy logic in which more than two possible truth-value assignments are allowed overcomes the trap of probability theory when dealing with uncertain outcomes, thereby making the meaning of a certain prognostic statement easier to understand by the patient. Summary At individual subject level the recourse to the term plausibility, related to fuzzy logic, would help the physician to communicate to the patient more efficiently in comparison with the term probability, related to binary logic. This would represent an evident advantage for the transfer of medical evidences to individual subjects. PMID:16188041

  2. Pulmonary phthalate exposure and asthma - is PPAR a plausible mechanistic link?

    PubMed Central

    Kocbach Bølling, Anette; Holme, Jørn A; Bornehag, Carl Gustaf; Nygaard, Unni C; Bertelsen, Randi J; Nånberg, Eewa; Bodin, Johanna; Sakhi, Amrit Kaur; Thomsen, Cathrine; Becher, Rune

    2013-01-01

    Due to their extensive use as plasticisers in numerous consumer products, phthalates have become ubiquitous environmental contaminants. An increasing number of epidemiological studies suggest that exposure to phthalates may be associated with worsening or development of airway diseases. Peroxisome Proliferation Activated Receptors (PPAR)s, identified as important targets for phthalates in early studies in rodent liver, have been suggested as a possible mechanistic link. In this review we discuss the likelihood of an involvement of PPARs in asthma development and exacerbation due to pulmonary phthalate exposure. First, we go through the literature on indoor air levels of phthalates and pulmonary phthalate kinetics. These data are then used to estimate the pulmonary phthalate levels due to inhalation exposure. Secondly, the literature on phthalate-induced activation or modulation of PPARs is summarized. Based on these data, we discuss whether pulmonary phthalate exposure is likely to cause PPAR activation, and if this is a plausible mechanism for adverse effects of phthalates in the lung. It is concluded that the pulmonary concentrations of some phthalates may be sufficient to cause a direct activation of PPARs. Since PPARs mainly mediate anti-inflammatory effects in the lungs, a direct activation is not a likely molecular mechanism for adverse effects of phthalates. However, possible modulatory effects of phthalates on PPARs deserve further investigation, including partial antagonist effects and/or cross talk with other signalling pathways. Moreover other mechanisms, including interactions between phthalates and other receptors, could also contribute to possible adverse pulmonary effects of phthalates. PMID:26622216

  3. Plausible ergogenic effects of vitamin D on athletic performance and recovery.

    PubMed

    Dahlquist, Dylan T; Dieter, Brad P; Koehle, Michael S

    2015-01-01

    The purpose of this review is to examine vitamin D in the context of sport nutrition and its potential role in optimizing athletic performance. Vitamin D receptors (VDR) and vitamin D response elements (VDREs) are located in almost every tissue within the human body including skeletal muscle. The hormonally-active form of vitamin D, 1,25-dihydroxyvitamin D, has been shown to play critical roles in the human body and regulates over 900 gene variants. Based on the literature presented, it is plausible that vitamin D levels above the normal reference range (up to 100 nmol/L) might increase skeletal muscle function, decrease recovery time from training, increase both force and power production, and increase testosterone production, each of which could potentiate athletic performance. Therefore, maintaining higher levels of vitamin D could prove beneficial for athletic performance. Despite this situation, large portions of athletic populations are vitamin D deficient. Currently, the research is inconclusive with regards to the optimal intake of vitamin D, the specific forms of vitamin D one should ingest, and the distinct nutrient-nutrient interactions of vitamin D with vitamin K that affect arterial calcification and hypervitaminosis. Furthermore, it is possible that dosages exceeding the recommendations for vitamin D (i.e. dosages up to 4000-5000 IU/day), in combination with 50 to 1000 mcg/day of vitamin K1 and K2 could aid athletic performance. This review will investigate these topics, and specifically their relevance to athletic performance. PMID:26288575

  4. One plausible reason for the change in ENSO characteristics in the 2000s

    NASA Astrophysics Data System (ADS)

    Stepanov, V. N.

    2013-07-01

    It is well known that El Niño Southern Oscillation (ENSO) causes floods, droughts and the collapse of fisheries, therefore forecasting of ENSO is an important task in climate researches. Variations in the equatorial warm water volume of the tropical Pacific and wind variability in the western equatorial Pacific has been considered to be a good ENSO predictor. However, in the 2000s, the interrelationship between these two characteristics and ENSO onsets became weak. This article attempts to find some plausible explanation for this. The results presented here demonstrate a possible link between the variability of atmospheric conditions over the Southern Ocean and their impact on the ocean circulation leading to the amplifying/triggering of ENSO events. It is shown that the variability of the atmospheric conditions upstream of Drake Passage can strongly influence ENSO events. The interrelationship between ENSO and variability in the equatorial warm water volume of the equatorial Pacific, together with wind variability in the western equatorial Pacific has recently weakened. It can be explained by the fact that the process occurred in the Southern Ocean recently became a major contributor amplifying ENSO events (in comparison with the processes of interaction between the atmosphere and the ocean in the tropics of the Pacific). Likely it is due to a warmer ocean state observed from the end of the 1990s that led to smaller atmospheric variability in the tropics and insignificant their changes in the Southern Ocean.

  5. One plausible reason for the change in ENSO characteristics in the 2000s

    NASA Astrophysics Data System (ADS)

    Stepanov, V. N.

    2014-03-01

    It is well known that El Niño Southern Oscillation (ENSO) causes floods, droughts in different regions of the Earth and the collapse of fisheries in the tropical Pacific, therefore forecasting of ENSO is an important task in climate researches. Variations in the equatorial warm water volume of the tropical Pacific and wind variability in the western equatorial Pacific has been considered to be a good ENSO predictor. However, in the 2000s, the interrelationship between these two characteristics and ENSO onsets became weak. This article attempts to find some plausible explanation for this. The results presented here demonstrate a possible link between the variability of atmospheric conditions over the Southern Ocean and their impact on the ocean circulation leading to the amplifying of ENSO events. It is shown that the variability of the atmospheric conditions upstream of Drake Passage can strongly influence ENSO events. The interrelationship between ENSO and variability in the equatorial warm water volume of the equatorial Pacific, together with wind variability in the western equatorial Pacific has recently weakened. It can be explained by the fact that the process occurred in the Southern Ocean recently became a major contributor amplifying ENSO events (in comparison with the processes of interaction between the atmosphere and the ocean in the tropics of the Pacific). Likely it is due to a warmer ocean state observed from the end of the 1990s that led to smaller atmospheric variability in the tropics and insignificant their changes in the Southern Ocean.

  6. Mindfulness and Cardiovascular Disease Risk: State of the Evidence, Plausible Mechanisms, and Theoretical Framework.

    PubMed

    Loucks, Eric B; Schuman-Olivier, Zev; Britton, Willoughby B; Fresco, David M; Desbordes, Gaelle; Brewer, Judson A; Fulwiler, Carl

    2015-12-01

    The purpose of this review is to provide (1) a synopsis on relations of mindfulness with cardiovascular disease (CVD) and major CVD risk factors, and (2) an initial consensus-based overview of mechanisms and theoretical framework by which mindfulness might influence CVD. Initial evidence, often of limited methodological quality, suggests possible impacts of mindfulness on CVD risk factors including physical activity, smoking, diet, obesity, blood pressure, and diabetes regulation. Plausible mechanisms include (1) improved attention control (e.g., ability to hold attention on experiences related to CVD risk, such as smoking, diet, physical activity, and medication adherence), (2) emotion regulation (e.g., improved stress response, self-efficacy, and skills to manage craving for cigarettes, palatable foods, and sedentary activities), and (3) self-awareness (e.g., self-referential processing and awareness of physical sensations due to CVD risk factors). Understanding mechanisms and theoretical framework should improve etiologic knowledge, providing customized mindfulness intervention targets that could enable greater mindfulness intervention efficacy. PMID:26482755

  7. Place illusion and plausibility can lead to realistic behaviour in immersive virtual environments

    PubMed Central

    Slater, Mel

    2009-01-01

    In this paper, I address the question as to why participants tend to respond realistically to situations and events portrayed within an immersive virtual reality system. The idea is put forward, based on the experience of a large number of experimental studies, that there are two orthogonal components that contribute to this realistic response. The first is ‘being there’, often called ‘presence’, the qualia of having a sensation of being in a real place. We call this place illusion (PI). Second, plausibility illusion (Psi) refers to the illusion that the scenario being depicted is actually occurring. In the case of both PI and Psi the participant knows for sure that they are not ‘there’ and that the events are not occurring. PI is constrained by the sensorimotor contingencies afforded by the virtual reality system. Psi is determined by the extent to which the system can produce events that directly relate to the participant, the overall credibility of the scenario being depicted in comparison with expectations. We argue that when both PI and Psi occur, participants will respond realistically to the virtual reality. PMID:19884149

  8. Plausible explanation for the {Delta}{sub 5/2}{sup +}(2000) puzzle

    SciTech Connect

    Xie Jujun; Martinez Torres, A.; Oset, E.; Gonzalez, P.

    2011-05-15

    From a Faddeev calculation for the {pi}-({Delta}{rho}){sub N{sub 5/2}{sup -}{sub (1675)}} system we show the plausible existence of three dynamically generated I(J{sup P})=3/2(5/2{sup +}) baryon states below 2.3 GeV, whereas only two resonances, {Delta}{sub 5/2{sup +}}(1905)(****) and {Delta}{sub 5/2{sup +}}(2000)(**), are cataloged in the Particle Data Book Review. Our results give theoretical support to data analyses extracting two distinctive resonances, {Delta}{sub 5/2{sup +}}({approx}1740) and {Delta}{sub 5/2{sup +}}({approx}2200), from which the mass of {Delta}{sub 5/2{sup +}}(2000)(**) is estimated. We propose that these two resonances should be cataloged instead of {Delta}{sub 5/2{sup +}}(2000). This proposal gets further support from the possible assignment of the other baryon states found in the approach in the I=1/2,3/2 with J{sup P}=1/2{sup +},3/2{sup +},5/2{sup +} sectors to known baryonic resonances. In particular, {Delta}{sub 1/2{sup +}}(1750)(*) is naturally interpreted as a {pi}N{sub 1/2{sup -}}(1650) bound state.

  9. CD25 signaling regulates the function and stability of peripheral Foxp3+ regulatory T cells derived from the spleen and lymph nodes of mice.

    PubMed

    Wang, Kunpeng; Gu, Jian; Ni, Xuhao; Ding, Zheng; Wang, Qi; Zhou, Haoming; Zheng, SongGuo; Li, Bin; Lu, Ling

    2016-08-01

    Regulatory T cells (Tregs) play a critical role in sustaining immune tolerance and maintaining immune balance to alloantigen after transplatation. However, the functions of peripheral Tregs in different organs have not been fully characterized. Here, we showed that spleen-derived Tregs exhibited higher expression of Foxp3, greater suppressive capacity, and lower levels of IL-17A secretion than lymph node-derived Tregs in vitro in the presence or absence of inflammatory cytokines, such as IL-6. We found a higher percentage of CD25(bright) Tregs among spleen-derived Tregs than among lymph node-derived Tregs. Additionally, in vivo experiments demonstrated that adoptive transfer of spleen-derived Tregs, but not lymph node-derived Tregs, alleviated ischemia-reperfusion injury. These results reveal novel functions of Tregs derived from peripheral organs. In particular, spleen-derived Tregs, primarily consisting of CD25(bright) cells, may provide a more significant contribution to the suppression of immune-mediated autoimmune and inflammatory disease. PMID:27344615

  10. Conformational and Thermal Stability Improvements for the Large-Scale Production of Yeast-Derived Rabbit Hemorrhagic Disease Virus-Like Particles as Multipurpose Vaccine

    PubMed Central

    Méndez, Lídice; González, Nemecio; Parra, Francisco; Martín-Alonso, José M.; Limonta, Miladys; Sánchez, Kosara; Cabrales, Ania; Estrada, Mario P.; Rodríguez-Mallón, Alina; Farnós, Omar

    2013-01-01

    Recombinant virus-like particles (VLP) antigenically similar to rabbit hemorrhagic disease virus (RHDV) were recently expressed at high levels inside Pichia pastoris cells. Based on the potential of RHDV VLP as platform for diverse vaccination purposes we undertook the design, development and scale-up of a production process. Conformational and stability issues were addressed to improve process control and optimization. Analyses on the structure, morphology and antigenicity of these multimers were carried out at different pH values during cell disruption and purification by size-exclusion chromatography. Process steps and environmental stresses in which aggregation or conformational instability can be detected were included. These analyses revealed higher stability and recoveries of properly assembled high-purity capsids at acidic and neutral pH in phosphate buffer. The use of stabilizers during long-term storage in solution showed that sucrose, sorbitol, trehalose and glycerol acted as useful aggregation-reducing agents. The VLP emulsified in an oil-based adjuvant were subjected to accelerated thermal stress treatments. None to slight variations were detected in the stability of formulations and in the structure of recovered capsids. A comprehensive analysis on scale-up strategies was accomplished and a nine steps large-scale production process was established. VLP produced after chromatographic separation protected rabbits against a lethal challenge. The minimum protective dose was identified. Stabilized particles were ultimately assayed as carriers of a foreign viral epitope from another pathogen affecting a larger animal species. For that purpose, a linear protective B-cell epitope from Classical Swine Fever Virus (CSFV) E2 envelope protein was chemically coupled to RHDV VLP. Conjugates were able to present the E2 peptide fragment for immune recognition and significantly enhanced the peptide-specific antibody response in vaccinated pigs. Overall these results

  11. Effects of Reading Span and Plausibility in the Reanalysis of "Wh"-Gaps by Chinese-English Second Language Speakers

    ERIC Educational Resources Information Center

    Dussias, Paola E.; Pinar, Pilar

    2010-01-01

    This study utilizes a moving window technique to investigate how individual cognitive resources (operationalized in terms of reading span scores) might modulate the extent to which native English speakers and Chinese second language (L2) learners of English utilize plausibility information to recover from an initial misparse in the processing of…

  12. Evaporative water loss is a plausible explanation for mortality of bats from white-nose syndrome.

    PubMed

    Willis, Craig K R; Menzies, Allyson K; Boyles, Justin G; Wojciechowski, Michal S

    2011-09-01

    White-nose syndrome (WNS) has caused alarming declines of North American bat populations in the 5 years since its discovery. Affected bats appear to starve during hibernation, possibly because of disruption of normal cycles of torpor and arousal. The importance of hydration state and evaporative water loss (EWL) for influencing the duration of torpor bouts in hibernating mammals recently led to "the dehydration hypothesis," that cutaneous infection of the wing membranes of bats with the fungus Geomyces destructans causes dehydration which in turn, increases arousal frequency during hibernation. This hypothesis predicts that uninfected individuals of species most susceptible to WNS, like little brown bats (Myotis lucifugus), exhibit high rates of EWL compared to less susceptible species. We tested the feasibility of this prediction using data from the literature and new data quantifying EWL in Natterer's bats (Myotis nattereri), a species that is, like other European bats, sympatric with G. destructans but does not appear to suffer significant mortality from WNS. We found that little brown bats exhibited significantly higher rates of normothermic EWL than did other bat species for which comparable EWL data are available. We also found that Natterer's bats exhibited significantly lower rates of EWL, in both wet and dry air, compared with values predicted for little brown bats exposed to identical relative humidity (RH). We used a population model to show that the increase in EWL required to cause the pattern of mortality observed for WNS-affected little brown bats was small, equivalent to a solitary bat hibernating exposed to RH of ∼95%, or clusters hibernating in ∼87% RH, as opposed to typical near-saturation conditions. Both of these results suggest the dehydration hypothesis is plausible and worth pursuing as a possible explanation for mortality of bats from WNS. PMID:21742778

  13. Assessment of data uncertainty and plausibility over the Nam Co Region, Tibet

    NASA Astrophysics Data System (ADS)

    Biskop, S.; Krause, P.; Helmschrot, J.; Fink, M.; Flügel, W.-A.

    2012-07-01

    One of the major challenges for water balance studies in the remote and mostly ungauged region of the Tibetan Plateau is the lack of suitable and reliable climate data to drive hydrological models. Ground observations are rare in the high-mountainous region of the Nam Co basin and only global and regional gridded climate products are available as model input data, but these data sets need to be carefully analysed if used as driving force for hydrological modelling. In this study, various global and regional gridded data products for temperature and precipitation were compared to assess spatio-temporal deviations between several data sets. For the comparison absolute and relative differences of annual and seasonal long-term means were calculated. Climatic trends were analysed by using the non-parametric Mann-Kendall trend test. In addition, gridded climate data sets were compared to meteorological observations in order to evaluate their plausibility. The comparative statistical analysis showed significant differences in the magnitude, the seasonality, the spatial pattern and the trend behaviour of the analysed climate variables, in particular for precipitation data. The identified inconsistencies underpin the necessity to quantify the uncertainty of such climate data. Moreover, the presented study highlights the importance of further research efforts to develop regional climate data sets with finer resolutions to reduce the model's uncertainty resulting from climate input data. Such higher resolution is needed for a sufficient representation of regional topographic and orographic effects in order to simulate important hydrological processes in mountainous areas like snow accumulation and melting.

  14. Evaluation designs for adequacy, plausibility and probability of public health programme performance and impact.

    PubMed

    Habicht, J P; Victora, C G; Vaughan, J P

    1999-02-01

    The question of why to evaluate a programme is seldom discussed in the literature. The present paper argues that the answer to this question is essential for choosing an appropriate evaluation design. The discussion is centered on summative evaluations of large-scale programme effectiveness, drawing upon examples from the fields of health and nutrition but the findings may be applicable to other subject areas. The main objective of an evaluation is to influence decisions. How complex and precise the evaluation must be depends on who the decision maker is and on what types of decisions will be taken as a consequence of the findings. Different decision makers demand not only different types of information but also vary in their requirements of how informative and precise the findings must be. Both complex and simple evaluations, however, should be equally rigorous in relating the design to the decisions. Based on the types of decisions that may be taken, a framework is proposed for deciding upon appropriate evaluation designs. Its first axis concerns the indicators of interest, whether these refer to provision or utilization of services, coverage or impact measures. The second axis refers to the type of inference to be made, whether this is a statement of adequacy, plausibility or probability. In addition to the above framework, other factors affect the choice of an evaluation design, including the efficacy of the intervention, the field of knowledge, timing and costs. Regarding the latter, decision makers should be made aware that evaluation costs increase rapidly with complexity so that often a compromise must be reached. Examples are given of how to use the two classification axes, as well as these additional factors, for helping decision makers and evaluators translate the need for evaluation--the why--into the appropriate design--the how. PMID:10195658

  15. Identifying plausible adverse drug reactions using knowledge extracted from the literature.

    PubMed

    Shang, Ning; Xu, Hua; Rindflesch, Thomas C; Cohen, Trevor

    2014-12-01

    Pharmacovigilance involves continually monitoring drug safety after drugs are put to market. To aid this process; algorithms for the identification of strongly correlated drug/adverse drug reaction (ADR) pairs from data sources such as adverse event reporting systems or Electronic Health Records have been developed. These methods are generally statistical in nature, and do not draw upon the large volumes of knowledge embedded in the biomedical literature. In this paper, we investigate the ability of scalable Literature Based Discovery (LBD) methods to identify side effects of pharmaceutical agents. The advantage of LBD methods is that they can provide evidence from the literature to support the plausibility of a drug/ADR association, thereby assisting human review to validate the signal, which is an essential component of pharmacovigilance. To do so, we draw upon vast repositories of knowledge that has been extracted from the biomedical literature by two Natural Language Processing tools, MetaMap and SemRep. We evaluate two LBD methods that scale comfortably to the volume of knowledge available in these repositories. Specifically, we evaluate Reflective Random Indexing (RRI), a model based on concept-level co-occurrence, and Predication-based Semantic Indexing (PSI), a model that encodes the nature of the relationship between concepts to support reasoning analogically about drug-effect relationships. An evaluation set was constructed from the Side Effect Resource 2 (SIDER2), which contains known drug/ADR relations, and models were evaluated for their ability to "rediscover" these relations. In this paper, we demonstrate that both RRI and PSI can recover known drug-adverse event associations. However, PSI performed better overall, and has the additional advantage of being able to recover the literature underlying the reasoning pathways it used to make its predictions. PMID:25046831

  16. Identifying plausible adverse drug reactions using knowledge extracted from the literature

    PubMed Central

    Shang, Ning; Xu, Hua; Rindflesch, Thomas C.; Cohen, Trevor

    2014-01-01

    Pharmacovigilance involves continually monitoring drug safety after drugs are put to market. To aid this process; algorithms for the identification of strongly correlated drug/adverse drug reaction (ADR) pairs from data sources such as adverse event reporting systems or Electronic Health Records have been developed. These methods are generally statistical in nature, and do not draw upon the large volumes of knowledge embedded in the biomedical literature. In this paper, we investigate the ability of scalable Literature Based Discovery (LBD) methods to identify side effects of pharmaceutical agents. The advantage of LBD methods is that they can provide evidence from the literature to support the plausibility of a drug/ ADR association, thereby assisting human review to validate the signal, which is an essential component of pharmacovigilance. To do so, we draw upon vast repositories of knowledge that has been extracted from the biomedical literature by two Natural Language Processing tools, MetaMap and SemRep. We evaluate two LBD methods that scale comfortably to the volume of knowledge available in these repositories. Specifically, we evaluate Reflective Random Indexing (RRI), a model based on concept-level co-occurrence, and Predication-based Semantic Indexing (PSI), a model that encodes the nature of the relationship between concepts to support reasoning analogically about drug-effect relationships. An evaluation set was constructed from the Side Effect Resource 2 (SIDER2), which contains known drug/ADR relations, and models were evaluated for their ability to “rediscover” these relations. In this paper, we demonstrate that both RRI and PSI can recover known drug-adverse event associations. However, PSI performed better overall, and has the additional advantage of being able to recover the literature underlying the reasoning pathways it used to make its predictions. PMID:25046831

  17. Constructing a 'plausible narrative of progress' for nursing: a neopragmatist suggestion.

    PubMed

    Mason, Walter H

    2009-01-01

    Identity, difference, and the associated subject of cultural diversity pose challenges for nursing. As the demographics of the world change, demands are rising for nurses to provide sensitive, individualized care to people living in our ever-changing global community. Issues concerning gender, sexuality, disability, age, language, economic and occupational status, multiculturalism, and ethnicity are made more complex because many of these topics strike a personal chord for individual nurses. In order for nursing to provide appropriate care to the world's people and to meet future challenges, nursing must define itself in new ways. Kikuchi and Simmons have stated that the best way for nursing to approach this task is through the development of a 'sound' philosophy of nursing that will 'accommodate diversity in nursing thought'. They contend that before we can establish a philosophy of nursing, nurses will have to agree upon the nature of reality, human beings, truth, and knowledge. This paper will suggest that neopragmatism, as described by Richard Rorty, is a way to assure diversity of thought in nursing. However, I will argue against the requirement for this philosophy to be 'sound' in the sense that Kikuchi and Simmons use this term. In place of their call for 'truth and unity in nursing thought'. I will attempt to demonstrate how neopragmatic ideas relate to the construction of what Rorty called a unifying 'plausible narrative of progress'. This change will allow nursing to abandon the dead end debate over epistemologies and instead focus on more important issues related to improving nursing practice. PMID:19154292

  18. Multiple Solutions to the Same Problem: Utilization of Plausibility and Syntax in Sentence Comprehension by Older Adults with Impaired Hearing

    PubMed Central

    Amichetti, Nicole M.; White, Alison G.; Wingfield, Arthur

    2016-01-01

    A fundamental question in psycholinguistic theory is whether equivalent success in sentence comprehension may come about by different underlying operations. Of special interest is whether adult aging, especially when accompanied by reduced hearing acuity, may shift the balance of reliance on formal syntax vs. plausibility in determining sentence meaning. In two experiments participants were asked to identify the thematic roles in grammatical sentences that contained either plausible or implausible semantic relations. Comprehension of sentence meanings was indexed by the ability to correctly name the agent or the recipient of an action represented in the sentence. In Experiment 1 young and older adults’ comprehension was tested for plausible and implausible sentences with the meaning expressed with either an active-declarative or a passive syntactic form. In Experiment 2 comprehension performance was examined for young adults with age-normal hearing, older adults with good hearing acuity, and age-matched older adults with mild-to-moderate hearing loss for plausible or implausible sentences with meaning expressed with either a subject-relative (SR) or an object-relative (OR) syntactic structure. Experiment 1 showed that the likelihood of interpreting a sentence according to its literal meaning was reduced when that meaning expressed an implausible relationship. Experiment 2 showed that this likelihood was further decreased for OR as compared to SR sentences, and especially so for older adults whose hearing impairment added to the perceptual challenge. Experiment 2 also showed that working memory capacity as measured with a letter-number sequencing task contributed to the likelihood that listeners would base their comprehension responses on the literal syntax even when this processing scheme yielded an implausible meaning. Taken together, the results of both experiments support the postulate that listeners may use more than a single uniform processing strategy for

  19. Wind-Tunnel Investigation at Low Speed of the Rolling Stability Derivatives of a 1/9-Scale Powered Model of the Convair XFY-1 Vertically Rising Airplane, TED No. NACA DE 373

    NASA Technical Reports Server (NTRS)

    Queijo, M. J.; Wolhart, Walter D.; Fletcher, H. S.

    1953-01-01

    An experimental investigation has been conducted in the Langley stability tunnel at low speed to determine the rolling stability derivatives of a 1/9-scale powered model of the Convair XFY-1 vertically rising airplane. Effects of thrust coefficient were investigated for the complete model and for certain components of the model. Effects of control deflections and of propeller blade angle were investigated for the complete model. Most of the tests were made through an angle-of-attack range from about -4deg to 29deg, and the thrust coefficient range was from 0 to 0.7. In order to expedite distribution of these data, no analysis of the data has been prepared for this paper.

  20. Silver Ions in Non-canonical DNA Base Pairs: Metal-Mediated Mismatch Stabilization of 2'-Deoxyadenosine and 7-Deazapurine Derivatives with 2'-Deoxycytidine and 2'-Deoxyguanosine.

    PubMed

    Yang, Haozhe; Seela, Frank

    2016-09-01

    Novel silver-mediated dA-dC, dA*-dC, and dA*-dG base pairs were formed in a natural DNA double helix environment (dA* denotes 7-deaza-dA, 7-deaza-7-iodo-dA, and 7-cyclopropyl-7-deaza-dA). 7-Deazapurine nucleosides enforce silver ion binding and direct metal-mediated base pair formation to their Watson-Crick face. New phosphoramidites were prepared from 7-deaza-dA, 7-deaza-7-iodo-dA, and 7-cyclopropyl-7-deaza-dA, which contain labile isobutyryl protecting groups. Solid-phase synthesis furnished oligonucleotides that contain mismatches in near central positions. Increased thermal stabilities (higher Tm values) were observed for oligonucleotide duplexes with non-canonical dA*-dC and dA-dC pairs in the presence of silver ions. The stability of the silver-mediated base pairs was pH dependent. Silver ion binding was not observed for the dA-dG mismatch but took place when mismatches were formed between 7-deazaadenine and guanine. The specific binding of silver ions was confirmed by stoichiometric UV titration experiments, which proved that one silver ion is captured by one mismatch. The stability increase of canonical DNA mismatches might have an impact on cellular DNA repair. PMID:27492501

  1. Long-term rice cultivation stabilizes soil organic carbon and promotes soil microbial activity in a salt marsh derived soil chronosequence

    NASA Astrophysics Data System (ADS)

    Wang, Ping; Liu, Yalong; Li, Lianqing; Cheng, Kun; Zheng, Jufeng; Zhang, Xuhui; Zheng, Jinwei; Joseph, Stephen; Pan, Genxing

    2015-10-01

    Soil organic carbon (SOC) sequestration with enhanced stable carbon storage has been widely accepted as a very important ecosystem property. Yet, the link between carbon stability and bio-activity for ecosystem functioning with OC accumulation in field soils has not been characterized. We assessed the changes in microbial activity versus carbon stability along a paddy soil chronosequence shifting from salt marsh in East China. We used mean weight diameter, normalized enzyme activity (NEA) and carbon gain from straw amendment for addressing soil aggregation, microbial biochemical activity and potential C sequestration, respectively. In addition, a response ratio was employed to infer the changes in all analyzed parameters with prolonged rice cultivation. While stable carbon pools varied with total SOC accumulation, soil respiration and both bacterial and fungal diversity were relatively constant in the rice soils. Bacterial abundance and NEA were positively but highly correlated to total SOC accumulation, indicating an enhanced bio-activity with carbon stabilization. This could be linked to an enhancement of particulate organic carbon pool due to physical protection with enhanced soil aggregation in the rice soils under long-term rice cultivation. However, the mechanism underpinning these changes should be explored in future studies in rice soils where dynamic redox conditions exist.

  2. Long-term rice cultivation stabilizes soil organic carbon and promotes soil microbial activity in a salt marsh derived soil chronosequence

    PubMed Central

    Wang, Ping; Liu, Yalong; Li, Lianqing; Cheng, Kun; Zheng, Jufeng; Zhang, Xuhui; Zheng, Jinwei; Joseph, Stephen; Pan, Genxing

    2015-01-01

    Soil organic carbon (SOC) sequestration with enhanced stable carbon storage has been widely accepted as a very important ecosystem property. Yet, the link between carbon stability and bio-activity for ecosystem functioning with OC accumulation in field soils has not been characterized. We assessed the changes in microbial activity versus carbon stability along a paddy soil chronosequence shifting from salt marsh in East China. We used mean weight diameter, normalized enzyme activity (NEA) and carbon gain from straw amendment for addressing soil aggregation, microbial biochemical activity and potential C sequestration, respectively. In addition, a response ratio was employed to infer the changes in all analyzed parameters with prolonged rice cultivation. While stable carbon pools varied with total SOC accumulation, soil respiration and both bacterial and fungal diversity were relatively constant in the rice soils. Bacterial abundance and NEA were positively but highly correlated to total SOC accumulation, indicating an enhanced bio-activity with carbon stabilization. This could be linked to an enhancement of particulate organic carbon pool due to physical protection with enhanced soil aggregation in the rice soils under long-term rice cultivation. However, the mechanism underpinning these changes should be explored in future studies in rice soils where dynamic redox conditions exist. PMID:26503629

  3. Long-term rice cultivation stabilizes soil organic carbon and promotes soil microbial activity in a salt marsh derived soil chronosequence.

    PubMed

    Wang, Ping; Liu, Yalong; Li, Lianqing; Cheng, Kun; Zheng, Jufeng; Zhang, Xuhui; Zheng, Jinwei; Joseph, Stephen; Pan, Genxing

    2015-01-01

    Soil organic carbon (SOC) sequestration with enhanced stable carbon storage has been widely accepted as a very important ecosystem property. Yet, the link between carbon stability and bio-activity for ecosystem functioning with OC accumulation in field soils has not been characterized. We assessed the changes in microbial activity versus carbon stability along a paddy soil chronosequence shifting from salt marsh in East China. We used mean weight diameter, normalized enzyme activity (NEA) and carbon gain from straw amendment for addressing soil aggregation, microbial biochemical activity and potential C sequestration, respectively. In addition, a response ratio was employed to infer the changes in all analyzed parameters with prolonged rice cultivation. While stable carbon pools varied with total SOC accumulation, soil respiration and both bacterial and fungal diversity were relatively constant in the rice soils. Bacterial abundance and NEA were positively but highly correlated to total SOC accumulation, indicating an enhanced bio-activity with carbon stabilization. This could be linked to an enhancement of particulate organic carbon pool due to physical protection with enhanced soil aggregation in the rice soils under long-term rice cultivation. However, the mechanism underpinning these changes should be explored in future studies in rice soils where dynamic redox conditions exist. PMID:26503629

  4. Exploring apposite therapeutic target for apoptosis in filarial parasite: a plausible hypothesis.

    PubMed

    Hande, Sneha; Goswami, Kalyan; Jena, Lingaraj; Reddy, Maryada Venkata Rami

    2014-03-01

    Human lymphatic filariasis is a parasitic disease with profound socioeconomic encumbrance owing to its associated disability, affecting predominantly but not limited to the developing nations of tropics and subtropics. There are several technical issues like poor therapeutic and preventive repertoire as well as administrative and infrastructural limitations which jeopardize the salvage measures and further complicate the plight. Therefore, considering the gravity of the problem, WHO has mandated (under tropical disease research scheme) for placing emphasis on validation of novel therapeutic targets against this disease with the unfortunate tag of 'neglected tropical disease'. However, dearth of knowledge of parasite biology viciously coupled with difficulty of access to parasitic material from suitable animal model along with growing cost burden of high end research poses formidable challenge. Based on the recent research evidences, here we propose a premise with targeted apoptotic impact as a novel rationale to be exploited towards anti-parasitic drug development. The new era of bioinformatics ushers in new optimism with a wide range of genomic and proteomic database in public domain. Such platform might offer wonders for drug research, but needs highly selective criterion specificity. In order to test our hypothesis presumptively, we deployed a scheme for identification of target proteins from filarial parasitic origin through wide database search with precise criteria of non-homology against the host along with functional essentiality for the parasite. Further screening for proteins with growth potential from such list of essential non-homologous proteins was undertaken to mine out suitable representative target for ensuing apoptotic impact though effective inhibitors. A unique protein enzyme, RNA dependent RNA polymerase, which besides its vital role in RNA virus is believed to have regulatory role in gene expression, emerged as a plausible target. This protein

  5. Robustness and adaptation reveal plausible cell cycle controlling subnetwork in Saccharomyces cerevisiae.

    PubMed

    Huang, Jiun-Yan; Huang, Chi-Wei; Kao, Kuo-Ching; Lai, Pik-Yin

    2013-04-10

    signal stimulus entries of check points into the cell cycle, which are consistent with experimental findings. This evolution strategy method can be applied adequately to extract the plausible yeast cell cycle subnetworks from the whole network. Connections between modules in the obtained cell cycle subnetworks reveal significant cell cycle control mechanisms. This method can also be useful when applied to other biological systems at various temporal and spatial scales for example, the gene transcription networks, and biological systems from mesoscopic scale, e.g cortical network in brain, to subcellular molecular networks. PMID:23274654

  6. TECHNICAL BASIS FOR DOE STANDARD 3013 EQUIVALENCY SUPPORTING REDUCED TEMPERATURE STABILIZATION OF OXALATE-DERIVED PLUTONIUM OXIDE PRODUCED BY THE HB-LINE FACILITY AT SAVANNAH RIVER SITE

    SciTech Connect

    Duffey, J.; Livingston, R.; Berg, J.; Veirs, D.

    2012-07-02

    The HB-Line (HBL) facility at the Savannah River Site (SRS) is designed to produce high-purity plutonium dioxide (PuO{sub 2}) which is suitable for future use in production of Mixed Oxide (MOX) fuel. The MOX Fuel Fabrication Facility (MFFF) requires PuO{sub 2} feed to be packaged per the U.S. Department of Energy (DOE) Standard 3013 (DOE-STD-3013) to comply with the facility's safety basis. The stabilization conditions imposed by DOE-STD-3013 for PuO{sub 2} (i.e., 950 C for 2 hours) preclude use of the HBL PuO{sub 2} in direct fuel fabrication and reduce the value of the HBL product as MFFF feedstock. Consequently, HBL initiated a technical evaluation to define acceptable operating conditions for production of high-purity PuO{sub 2} that fulfills the DOE-STD-3013 criteria for safe storage. The purpose of this document is to demonstrate that within the defined operating conditions, the HBL process will be equivalent for meeting the requirements of the DOE-STD-3013 stabilization process for plutonium-bearing materials from the DOE complex. The proposed 3013 equivalency reduces the prescribed stabilization temperature for high-purity PuO{sub 2} from oxalate precipitation processes from 950 C to 640 C and places a limit of 60% on the relative humidity (RH) at the lowest material temperature. The equivalency is limited to material produced using the HBL established flow sheet, for example, nitric acid anion exchange and Pu(IV) direct strike oxalate precipitation with stabilization at a minimum temperature of 640 C for four hours (h). The product purity must meet the MFFF acceptance criteria of 23,600 {micro}g/g Pu (i.e., 2.1 wt %) total impurities and chloride content less than 250 {micro}g/g of Pu. All other stabilization and packaging criteria identified by DOE-STD-3013-2012 or earlier revisions of the standard apply. Based on the evaluation of test data discussed in this document, the expert judgment of the authors supports packaging the HBL product under a 3013

  7. Apoptotic cell-derived sphingosine-1-phosphate promotes HuR-dependent cyclooxygenase-2 mRNA stabilization and protein expression.

    PubMed

    Johann, Axel M; Weigert, Andreas; Eberhardt, Wolfgang; Kuhn, Anne-Marie; Barra, Vera; von Knethen, Andreas; Pfeilschifter, Josef M; Brüne, Bernhard

    2008-01-15

    Removal of apoptotic cells by phagocytes is considered a pivotal immune regulatory process. Although considerable knowledge has been obtained on the postphagocytic macrophage phenotype, there is little information on molecular mechanisms, which provoke macrophage polarization. In this study, we show that human apoptotic Jurkat cells (AC) or AC-conditioned medium (CM) rapidly induces cyclooxygenase-2 (COX-2) expression in mouse RAW264.7 macrophages via sphingosine-1-phosphate (S1P). Pharmacological inhibition of S1P release from AC or using CM from cells with a knockdown of sphingosine kinase 2 in human MCF-7 cells abrogates this effect. Expression of COX-2 resulted from an increase in mRNA stability via its 3'-untranslated region (UTR), shown by COX-2-3'-UTR and AU-rich element-driven reporter assays. Western analysis corroborated increased nucleocytoplasmic shuttling of the RNA-binding protein HuR after CM treatment. RNA EMSA analysis revealed an S1P- and CM-mediated increase in HuR-RNA binding to a COX-2-specific UTR, whereas HuR knockdown pointed to its importance for S1P in CM-induced COX-2 expression. Immunofluorescence microscopy of phospholipase A2 (PLA2) and ELISA analysis of PGE2 revealed activation of PLA2 and production of PGE2 in response to CM but not S1P. S1P, released from AC, uses HuR to stabilize COX-2 mRNA and thus to increase COX-2 protein expression. However, only CM also activates PLA2 to provide the substrate for COX-2. Our data underscore the importance of S1P in AC-mediated immune regulation, by stabilizing COX-2 mRNA in macrophages, a prerequisite for PGE2 formation. PMID:18178864

  8. Investigations on the Stability, Oscillation, and Stress Conditions of Airplanes with Tab Control: First Partial Report. Derivation of the Equations of Motion and their General Solutions

    NASA Technical Reports Server (NTRS)

    Filzek, B.

    1949-01-01

    For the design and the construction of airplanes the control is of special significance, not only with regard to the flight mechhnical properties but also for the proportional arrangement of wing unit, fuselage, and tail unit. whereas these problems may be regarded as solved for direct control of airplane motions, that is, for immediate operation of the control surfaces, they are not clarified as to oscimtions, stability, and stress phenomena occurring in flight motions with Indirect control, ss realized for instance in tab control. Its modus operandi is based on the activation of a tab hinged to the trailing edge & the main control surface. Due to lift and drag variations, mcments originate about the axis of rotation of the main contnol surface which cause an up-or--down floating of the main control surface and thus a change in the direction of the airplane. Since this tab control means flying with free control surface , the treatment of this problem should provide the basis on which to judge stability, oscilhtton, and stress data.The present report is to represent a contribution toward the clarification of the problems arising and, to treat the longitudinal motion of an airplane.

  9. Stability and cellular studies of [rac-1,2-bis(4-fluorophenyl)-ethylenediamine][cyclobutane-1,1- dicarboxylato]platinum(II), a novel, highly active carboplatin derivative.

    PubMed

    Gust, R; Schnurr, B; Krauser, R; Bernhardt, G; Koch, M; Schmid, B; Hummel, E; Schönenberger, H

    1998-01-01

    The synthesis of the diastereomeric [1,2-bis(4-fluorophenyl)ethylenediamine][cyclobutane-1, 1-dicarboxylato]platinum(II) complexes, rac- and meso-4F-Pt(CBDC), the evaluation of their structures, their tumor-inhibiting properties and their stability in physiological environment are described (reference complexes: the dichloro- and sulfatoplatinum(II) analogues, carboplatin and cisplatin). The most interesting diastereomer, rac-4F-Pt(CBDC), equals cisplatin and surpasses carboplatin in its effect on human breast cancer cell lines (MCF-7 and MDA-MB-231). Rac-4F-Pt(CBDC) is largely insensitive against attack of nucleophiles e.g. Cl-, a prerequisite for sufficient stability in vivo and for fewer side effects. In accordance with this, in vitro studies on the binding of rac-4F-Pt(CBDC) to albumin, the main plasma protein, show that the free, non-protein-bound fraction is relatively high, coming close to that of carboplatin. These properties are of importance for the transferability of the promising effects found in the cell culture experiments to in vivo conditions. The distinctly better anti-breast cancer activity of rac-4F-Pt(CBDC) than of carboplatin has been attributed to its ability to accumulate in the tumor cells. The human ovarian cancer cell line NIH-OVCAR-3 is also strongly inhibited by rac-4F-Pt(CBDC). PMID:9860287

  10. Microtubule-stabilizing properties of the avocado-derived toxins (+)-(R)-persin and (+)-(R)-tetrahydropersin in cancer cells and activity of related synthetic analogs.

    PubMed

    Field, Jessica J; Kanakkanthara, Arun; Brooke, Darby G; Sinha, Saptarshi; Pillai, Sushila D; Denny, William A; Butt, Alison J; Miller, John H

    2016-06-01

    The avocado toxin (+)-R-persin (persin) is active at low micromolar concentrations against breast cancer cells and synergizes with the estrogen receptor modulator 4-hydroxytamoxifen. Previous studies in the estrogen receptor-positive breast cancer cell line MCF-7 indicate that persin acts as a microtubule-stabilizing agent. In the present study, we further characterize the properties of persin and several new synthetic analogues in human ovarian cancer cells. Persin and tetrahydropersin cause G2M cell cycle arrest and increase intracellular microtubule polymerization. One analog (4-nitrophenyl)-deshydroxypersin prevents cell proliferation and blocks cells in G1 of the cell cycle rather than G2M, suggesting an additional mode of action of these compounds independent of microtubules. Persin can synergize with other microtubule-stabilizing agents, and is active against cancer cells that overexpress the P-glycoprotein drug efflux pump. Evidence from Flutax-1 competition experiments suggests that while the persin binding site on β-tubulin overlaps the classical taxoid site where paclitaxel and epothilone bind, persin retains activity in cell lines with single amino acid mutations that affect these other taxoid site ligands. This implies the existence of a unique binding location for persin at the taxoid site. PMID:26968704

  11. Enhancing the Stability of CH3NH3PbBr3 Quantum Dots by Embedding in Silica Spheres Derived from Tetramethyl Orthosilicate in "Waterless" Toluene.

    PubMed

    Huang, Shouqiang; Li, Zhichun; Kong, Long; Zhu, Nanwen; Shan, Aidang; Li, Liang

    2016-05-11

    Methylammonium lead halide perovskites suffer from poor stability because of their high sensitivity to moisture. Inorganic material coatings of SiO2 are preferred for coupling with perovskites to improve their stability, whereas the conventional SiO2 formation method is unsuitable because it requires water. Here, a simple SiO2 generation method based on the high hydrolysis rate of tetramethyl orthosilicate in analytical-grade toluene was developed to avoid the addition of water and catalyst. As a result, SiO2-encapsulated CH3NH3PbBr3 quantum dots (MAPB-QDs/SiO2) were fabricated without decreasing the quantum yield. Photostability tests indicated that the MAPB-QDs/SiO2 samples were markedly more stable than the unencapsulated MAPB-QDs. The photoluminescence (PL) of the MAPB-QDs/SiO2 powders was maintained at 94.10% after 470 nm LED illumination for 7 h, which was much higher than the remnant PL (38.36%) of the pure MAPB-QD sample under a relative humidity of 60%. Similar test results were observed when the MAPB-QDs/SiO2 powders were incorporated into the poly(methyl methacrylate) films. The enhanced photostability is ascribed to the SiO2 barriers protecting the MAPB-QDs from degradation. PMID:27100461

  12. Effects of phospholipase A2 and its products on structural stability of human LDL: relevance to formation of LDL-derived lipid droplets[S

    PubMed Central

    Jayaraman, Shobini; Gantz, Donald L.; Gursky, Olga

    2011-01-01

    Hydrolysis and oxidation of LDL stimulate LDL entrapment in the arterial wall and promote inflammation and atherosclerosis via various mechanisms including lipoprotein fusion and lipid droplet formation. To determine the effects of FFA on these transitions, we hydrolyzed LDL by phospholipase A2 (PLA2), removed FFA by albumin, and analyzed structural stability of the modified lipoproteins. Earlier, we showed that heating induces LDL remodeling, rupture, and coalescence into lipid droplets resembling those found in atherosclerotic lesions. Here, we report how FFA affect these transitions. Circular dichroism showed that mild LDL lipolysis induces partial β-sheet unfolding in apolipoprotein B. Electron microscopy, turbidity, and differential scanning calorimetry showed that mild lipolysis promotes LDL coalescence into lipid droplets. FFA removal by albumin restores LDL stability but not the protein conformation. Consequently, FFA enhance LDL coalescence into lipid droplets. Similar effects of FFA were observed in minimally oxidized LDL, in LDL enriched with exogenous FFA, and in HDL and VLDL. Our results imply that FFA promote lipoprotein coalescence into lipid droplets and explain why LDL oxidation enhances such coalescence in vivo but hampers it in vitro. Such lipid droplet formation potentially contributes to the pro-atherogenic effects of FFA. PMID:21220788

  13. Stability of the resistance to the thiosemicarbazone derived from 5,6-dimethoxy-1-indanone, a non-nucleoside polymerase inhibitor of bovine viral diarrhea virus.

    PubMed

    Castro, Eliana F; Campos, Rodolfo H; Cavallaro, Lucía V

    2014-01-01

    Bovine viral diarrhea virus (BVDV) is the prototype Pestivirus. BVDV infection is distributed worldwide and causes serious problems for the livestock industry. The thiosemicarbazone of 5,6-dimethoxy-1-indanone (TSC) is a non-nucleoside polymerase inhibitor (NNI) of BVDV. All TSC-resistant BVDV variants (BVDV-TSCr T1-5) present an N264D mutation in the NS5B gene (RdRp) whereas the variant BVDV-TSCr T1 also presents an NS5B A392E mutation. In the present study, we carried out twenty passages of BVDV-TSCr T1-5 in MDBK cells in the absence of TSC to evaluate the stability of the resistance. The viral populations obtained (BVDV R1-5) remained resistant to the antiviral compound and conserved the mutations in NS5B associated with this phenotype. Along the passages, BVDV R2, R3 and R5 presented a delay in the production of cytopathic effect that correlated with a decrease in cell apoptosis and intracellular accumulation of viral RNA. The complete genome sequences that encode for NS2 to NS5B, Npro and Erns were analyzed. Additional mutations were detected in the NS5B of BVDV R1, R3 and R4. In both BVDV R2 and R3, most of the mutations found were localized in NS5A, whereas in BVDV R5, the only mutation fixed was NS5A V177A. These results suggest that mutations in NS5A could alter BVDV cytopathogenicity. In conclusion, the stability of the resistance to TSC may be due to the fixation of different compensatory mutations in each BVDV-TSCr. During their replication in a TSC-free medium, some virus populations presented a kind of interaction with the host cell that resembled a persistent infection: decreased cytopathogenicity and viral genome synthesis. This is the first report on the stability of antiviral resistance and on the evolution of NNI-resistant BVDV variants. The results obtained for BVDV-TSCr could also be applied for other NNIs. PMID:24950191

  14. Stability of the Resistance to the Thiosemicarbazone Derived from 5,6-Dimethoxy-1-Indanone, a Non-Nucleoside Polymerase Inhibitor of Bovine Viral Diarrhea Virus

    PubMed Central

    Castro, Eliana F.; Campos, Rodolfo H.; Cavallaro, Lucía V.

    2014-01-01

    Bovine viral diarrhea virus (BVDV) is the prototype Pestivirus. BVDV infection is distributed worldwide and causes serious problems for the livestock industry. The thiosemicarbazone of 5,6-dimethoxy-1-indanone (TSC) is a non-nucleoside polymerase inhibitor (NNI) of BVDV. All TSC-resistant BVDV variants (BVDV-TSCr T1–5) present an N264D mutation in the NS5B gene (RdRp) whereas the variant BVDV-TSCr T1 also presents an NS5B A392E mutation. In the present study, we carried out twenty passages of BVDV-TSCr T1–5 in MDBK cells in the absence of TSC to evaluate the stability of the resistance. The viral populations obtained (BVDV R1–5) remained resistant to the antiviral compound and conserved the mutations in NS5B associated with this phenotype. Along the passages, BVDV R2, R3 and R5 presented a delay in the production of cytopathic effect that correlated with a decrease in cell apoptosis and intracellular accumulation of viral RNA. The complete genome sequences that encode for NS2 to NS5B, Npro and Erns were analyzed. Additional mutations were detected in the NS5B of BVDV R1, R3 and R4. In both BVDV R2 and R3, most of the mutations found were localized in NS5A, whereas in BVDV R5, the only mutation fixed was NS5A V177A. These results suggest that mutations in NS5A could alter BVDV cytopathogenicity. In conclusion, the stability of the resistance to TSC may be due to the fixation of different compensatory mutations in each BVDV-TSCr. During their replication in a TSC-free medium, some virus populations presented a kind of interaction with the host cell that resembled a persistent infection: decreased cytopathogenicity and viral genome synthesis. This is the first report on the stability of antiviral resistance and on the evolution of NNI-resistant BVDV variants. The results obtained for BVDV-TSCr could also be applied for other NNIs. PMID:24950191

  15. Ternary inclusion complex formation and stabilization of limaprost, a prostaglandin E1 derivative, in the presence of α- and β-cyclodextrins in the solid state.

    PubMed

    Inoue, Yasuo; Iohara, Daisuke; Sekiya, Noboru; Yamamoto, Masanobu; Ishida, Hiroyuki; Sakiyama, Yoko; Hirayama, Fumitoshi; Arima, Hidetoshi; Uekama, Kaneto

    2016-07-25

    Limaprost/α-cyclodextrin (CD)/β-CD ternary inclusion complex was prepared by freeze-drying a solution containing all three components. Under humid conditions, limaprost was more stable in the ternary α-/β-CD inclusion complex than in the binary α- or β-CD complex. Specifically, during storage at 30°C/75% relative humidity (R.H.) for 4 weeks, about 19% of limaprost degraded into 17S,20-dimethyl-trans-Δ(2)-prostaglandin A1 (referred as 11-deoxy-Δ(10)) in the β-CD complex, 8.1% degraded in the α-CD complex, and only 2.2% degraded in the α-/β-CD complex. The mechanism of limaprost stabilization in the presence of both CDs was investigated by Raman and solid-state NMR spectroscopy and powder X-ray diffractometry. The fast degradation of limaprost to 11-deoxy-Δ(10) in the β-CD complex was due to the rapid crystallization of β-CD from the complex, liberating the free amorphous drug, which is susceptible to degradation. The dissociation and crystallization of β-CD from the inclusion complex were suppressed by freeze-drying limaprost in the presence of both α- and β-CDs. In addition, the interaction between limaprost and the two CDs was reinforced by inclusion of different moieties of limaprost: α-CD predominantly included the alkyl ω-chain, whereas β-CD included the five-membered ring. Thus, a stable ternary inclusion complex was formed that included limaprost, maintaining the amorphous state of the complex and dramatically stabilizing the drug under humid conditions. PMID:27286633

  16. Thermal stabilization of bicelles by a bile-salt-derived detergent: a combined ³¹P and ²H nuclear magnetic resonance study.

    PubMed

    Morales, Hannah Hazel; Saleem, Qasim; Macdonald, Peter M

    2014-12-23

    The properties of bicelles composed of mixtures of long-chain lipids dimyristoylphosphatidylcholine (DMPC) and dimyristoylphosphatidylglycerol (DMPG), stabilized by zwitterionic bile salt analogue 3-[(3-cholamidopropyl)dimethyl-d6-ammonio]-2-hydroxy-1-propanesulfonate (CHAPSO-d6), deuterated at both amino methyls, were investigated by a combination of (31)P and (2)H NMR, focusing on the behavior of CHAPSO as a function of temperature. For compositions of molar ratio q = [DMPC + DMPG]/[CHAPSO] = 3, R = [DMPG]/[DMPC + DMPG] = 0, 0.01 and 0.10 and lipid concentration CL = 25 wt % lipid at temperatures of between 30 and 60 °C, magnetic alignment was readily achieved as assessed via both (31)P NMR of the phospholipids and (2)H NMR of CHAPSO-d6. Increasing temperature yielded higher values for the chemical shift anisotropy of the former and the quadrupole splitting of the latter, consistent with the progressive migration of CHAPSO from edge regions into planar regions of the bicellar assemblies. However, relative to dihexadecyl phosphatidylcholine (DHPC), CHAPSO exhibited lower miscibility with DMPC, although the presence of DMPG enhanced this miscibility. At 65 °C, thermal instability became evident in the appearance of a separate isotropic component in both (31)P and (2)H NMR spectra. This isotropic phase was CHAPSO-enriched but less so as a function of increasing DMPG. These findings indicate that the enhanced thermal stability of CHAPSO- versus DHPC-containing bicelles arises from a combination of the larger surface area that edge CHAPSO is able to mask, mole for mole, and its relative preference for edge regions, plus, possibly, specific interactions with DMPG. PMID:25426518

  17. Determination of stability and control derivatives from the NASA F/A-18 HARV from flight data using the maximum likelihood method

    NASA Technical Reports Server (NTRS)

    Napolitano, Marcello R.

    1995-01-01

    This report is a compilation of PID (Proportional Integral Derivative) results for both longitudinal and lateral directional analysis that was completed during Fall 1994. It had earlier established that the maneuvers available for PID containing independent control surface inputs from OBES were not well suited for extracting the cross-coupling static (i.e., C(sub N beta)) or dynamic (i.e., C(sub Npf)) derivatives. This was due to the fact that these maneuvers were designed with the goal of minimizing any lateral directional motion during longitudinal maneuvers and vice-versa. This allows for greater simplification in the aerodynamic model as far as coupling between longitudinal and lateral directions is concerned. As a result, efforts were made to reanalyze this data and extract static and dynamic derivatives for the F/A-18 HARV (High Angle of Attack Research Vehicle) without the inclusion of the cross-coupling terms such that more accurate estimates of classical model terms could be acquired. Four longitudinal flights containing static PID maneuvers were examined. The classical state equations already available in pEst for alphadot, qdot and thetadot were used. Three lateral directional flights of PID static maneuvers were also examined. The classical state equations already available in pEst for betadot, p dot, rdot and phi dot were used. Enclosed with this document are the full set of longitudinal and lateral directional parameter estimate plots showing coefficient estimates along with Cramer-Rao bounds. In addition, a representative time history match for each type of meneuver tested at each angle of attack is also enclosed.

  18. High Genetic and Epigenetic Stability in Coffea arabica Plants Derived from Embryogenic Suspensions and Secondary Embryogenesis as Revealed by AFLP, MSAP and the Phenotypic Variation Rate

    PubMed Central

    Bobadilla Landey, Roberto; Cenci, Alberto; Georget, Frédéric; Bertrand, Benoît; Camayo, Gloria; Dechamp, Eveline; Herrera, Juan Carlos; Santoni, Sylvain; Lashermes, Philippe; Simpson, June; Etienne, Hervé

    2013-01-01

    Embryogenic suspensions that involve extensive cell division are risky in respect to genome and epigenome instability. Elevated frequencies of somaclonal variation in embryogenic suspension-derived plants were reported in many species, including coffee. This problem could be overcome by using culture conditions that allow moderate cell proliferation. In view of true-to-type large-scale propagation of C. arabica hybrids, suspension protocols based on low 2,4-D concentrations and short proliferation periods were developed. As mechanisms leading to somaclonal variation are often complex, the phenotypic, genetic and epigenetic changes were jointly assessed so as to accurately evaluate the conformity of suspension-derived plants. The effects of embryogenic suspensions and secondary embryogenesis, used as proliferation systems, on the genetic conformity of somatic embryogenesis-derived plants (emblings) were assessed in two hybrids. When applied over a 6 month period, both systems ensured very low somaclonal variation rates, as observed through massive phenotypic observations in field plots (0.74% from 200 000 plant). Molecular AFLP and MSAP analyses performed on 145 three year-old emblings showed that polymorphism between mother plants and emblings was extremely low, i.e. ranges of 0–0.003% and 0.07–0.18% respectively, with no significant difference between the proliferation systems for the two hybrids. No embling was found to cumulate more than three methylation polymorphisms. No relation was established between the variant phenotype (27 variants studied) and a particular MSAP pattern. Chromosome counting showed that 7 of the 11 variant emblings analyzed were characterized by the loss of 1–3 chromosomes. This work showed that both embryogenic suspensions and secondary embryogenesis are reliable for true-to-type propagation of elite material. Molecular analyses revealed that genetic and epigenetic alterations are particularly limited during coffee somatic

  19. Two-dimensional titanium carbonitrides and their hydroxylated derivatives: Structural, electronic properties and stability of MXenes Ti{sub 3}C{sub 2−x}N{sub x}(OH){sub 2} from DFTB calculations

    SciTech Connect

    Enyashin, A.N.; Ivanovskii, A.L.

    2013-11-15

    The structural, electronic properties and stability of the new MXene compounds—two-dimensional pristine carbonitrides Ti{sub 3}C{sub 2−x}N{sub x} and their hydroxylated derivatives Ti{sub 3}C{sub 2−x}N{sub x}(OH){sub 2} are studied by means of DFTB calculations. The genesis of the properties is discussed in the sequence: binary MXenes Ti{sub 3}C{sub 2} (Ti{sub 3}N{sub 2})→hydroxylated forms Ti{sub 3}C{sub 2}(OH){sub 2} (Ti{sub 3}N{sub 2}(OH){sub 2})→pristine MXene Ti{sub 3}C{sub 2−x}N{sub x}→hydroxylated Ti{sub 3}C{sub 2−x}N{sub x}(OH){sub 2}. All examined materials are metallic-like. The most favorable type of OH-covering is presented by the occupation of the hollow sites between three neighboring carbon (nitrogen) atoms. Two-dimensional MXene carbonitrides with random distribution of C and N atoms are found to be thermodynamically more favorable. - Graphical abstract: The side views of the optimized atomic structures of some examined hydroxylated derivatives of MXene Ti{sub 3}CN and their electronic band structures. Display Omitted - Highlights: • Very recently 2D titanium carbonitrides have been synthesized. • Structural, electronic properties and stability for these materials were evaluated. • The hydroxylated derivatives of 2D titanium carbonitrides are examined.

  20. Epithelial cell-derived periostin functions as a tumor suppressor in gastric cancer through stabilizing p53 and E-cadherin proteins via the Rb/E2F1/p14ARF/Mdm2 signaling pathway.

    PubMed

    Lv, Hongjun; Liu, Rui; Fu, Jiao; Yang, Qi; Shi, Jing; Chen, Pu; Ji, Meiju; Shi, Bingyin; Hou, Peng

    2014-01-01

    Periostin is usually considered as an oncogene in diverse human cancers, including breast, prostate, colon, esophagus, and pancreas cancers, whereas it acts as a tumor suppressor in bladder cancer. In gastric cancer, it has been demonstrated that periglandular periostin expression is decreased whereas stromal periostin expression is significantly increased as compared with normal gastric tissues. Moreover, periostin produced by stromal myofibroblasts markedly promotes gastric cancer cell growth. These observations suggest that periostin derived from different types of cells may play distinct biological roles in gastric tumorigenesis. The aim of this study was to explore the biological functions and related molecular mechanisms of epithelial cell-derived periostin in gastric cancer. Our data showed that periglandular periostin was significantly down-regulated in gastric cancer tissues as compared with matched normal gastric mucosa. In addition, its expression in metastatic lymph nodes was significantly lower than that in their primary cancer tissues. Our data also demonstrated that periglandular periostin expression was negatively associated with tumor stage. More importantly, restoration of periostin expression in gastric cancer cells dramatically suppressed cell growth and invasiveness. Elucidation of the mechanisms involved revealed that periostin restoration enhanced Rb phosphorylation and sequentially activated the transcription of E2F1 target gene p14(ARF), leading to Mdm2 inactivation and the stabilization of p53 and E-cadherin proteins. Strikingly, these effects of periostin were abolished upon Rb deletion. Collectively, we have for the first time demonstrated that epithelial cell-derived periostin exerts tumor-suppressor activities in gastric cancer through stabilizing p53 and E-cadherin proteins via the Rb/E2F1/p14(ARF)/Mdm2 signaling pathway. PMID:25486483

  1. Silica-deposited phospholipid nanotubules as a plausible drug targeting system.

    PubMed

    Kim, Il; Park, Yun Hwan; Rey, Diego A; Batt, Carl A

    2008-11-01

    An aqueous dispersion of self-organized phospholipid tubules has been utilized as the template for silica-deposited nanotubules (approximately 0.5 microm thick and >10 microm long) by a sol-gel method. The formation of the hybrid tubules was mechanistically investigated by controlled sol-gel reaction. The incorporation of silica increases the mechanical and thermal stability of tubule geometry. After bioconjugating Ni(2+)-nitrilotriacetic acid (Ni-NTA) to the surface of chemically modified tubules containing primary amine groups, green fluorescent protein (GFP)-6 His and A33scFv-6 His were further bioconjugated in order to investigate a potential application of these hollow silica tubules as vehicle for targeted controlled release. The resulting tubules bound and internalized to SW1222 endothelial human colon carcinoma cells that express the A33 cell-surface glycoprotein more specifically than HT29 cells that do not express this antigen. PMID:18982520

  2. Borophosphates and silicophosphates as plausible contributors to the emergence of life.

    PubMed

    da Silva, José A L; Holm, Nils G

    2014-10-01

    Scientific explanations for the origin of life are incomplete and may differ on some issues. Here, we argue that some prebiological steps have occurred in environments with borophosphates and/or silicophosphates in the form of hydrogels, on the basis of their chemical groups and structural properties. These could have decreased the diffusion rate of some prebiotic molecules, stabilized molecules with vicinal cis-diol groups, reduced the hydrolytic activity of water and inserted catalytic metal ions into their networks. Additionally, these hydrogels could have acted as reaction media, supplied a phosphate source for phosphorylations and produced crystals that may have permitted enantiomeric enrichment of prebiotic molecules, thus providing conditions for the emergence of protocells. PMID:24674693

  3. The Reference Ability Neural Network Study: Life-time stability of reference-ability neural networks derived from task maps of young adults.

    PubMed

    Habeck, C; Gazes, Y; Razlighi, Q; Steffener, J; Brickman, A; Barulli, D; Salthouse, T; Stern, Y

    2016-01-15

    Analyses of large test batteries administered to individuals ranging from young to old have consistently yielded a set of latent variables representing reference abilities (RAs) that capture the majority of the variance in age-related cognitive change: Episodic Memory, Fluid Reasoning, Perceptual Processing Speed, and Vocabulary. In a previous paper (Stern et al., 2014), we introduced the Reference Ability Neural Network Study, which administers 12 cognitive neuroimaging tasks (3 for each RA) to healthy adults age 20-80 in order to derive unique neural networks underlying these 4 RAs and investigate how these networks may be affected by aging. We used a multivariate approach, linear indicator regression, to derive a unique covariance pattern or Reference Ability Neural Network (RANN) for each of the 4 RAs. The RANNs were derived from the neural task data of 64 younger adults of age 30 and below. We then prospectively applied the RANNs to fMRI data from the remaining sample of 227 adults of age 31 and above in order to classify each subject-task map into one of the 4 possible reference domains. Overall classification accuracy across subjects in the sample age 31 and above was 0.80±0.18. Classification accuracy by RA domain was also good, but variable; memory: 0.72±0.32; reasoning: 0.75±0.35; speed: 0.79±0.31; vocabulary: 0.94±0.16. Classification accuracy was not associated with cross-sectional age, suggesting that these networks, and their specificity to the respective reference domain, might remain intact throughout the age range. Higher mean brain volume was correlated with increased overall classification accuracy; better overall performance on the tasks in the scanner was also associated with classification accuracy. For the RANN network scores, we observed for each RANN that a higher score was associated with a higher corresponding classification accuracy for that reference ability. Despite the absence of behavioral performance information in the

  4. Protein Dynamics and Stability: The Distribution of Atomic Fluctuations in Thermophilic and Mesophilic Dihydrofolate Reductase Derived Using Elastic Incoherent Neutron Scattering

    SciTech Connect

    Meinhold, Lars; Clement, David; Tehei, M; Daniel, R. M.; Finney, J.L.; Smith, Jeremy C

    2008-11-01

    The temperature dependence of the dynamics of mesophilic and thermophilic dihydrofolate reductase is examined using elastic incoherent neutron scattering. It is demonstrated that the distribution of atomic displacement amplitudes can be derived from the elastic scattering data by assuming a (Weibull) functional form that resembles distributions seen in molecular dynamics simulations. The thermophilic enzyme has a significantly broader distribution than its mesophilic counterpart. Furthermore, although the rate of increase with temperature of the atomic mean-square displacements extracted from the dynamic structure factor is found to be comparable for both enzymes, the amplitudes are found to be slightly larger for the thermophilic enzyme. Therefore, these results imply that the thermophilic enzyme is the more flexible of the two.

  5. Increases thermal stability and cellulose-binding capacity of Cryptococcus sp. S-2 lipase by fusion of cellulose binding domain derived from Trichoderma reesei

    SciTech Connect

    Thongekkaew, Jantaporn; Ikeda, Hiroko; Iefuji, Haruyuki

    2012-03-30

    Highlights: Black-Right-Pointing-Pointer The CSLP and fusion enzyme were successfully expressed in the Pichia pastoris. Black-Right-Pointing-Pointer The fusion enzyme was stable at 80 Degree-Sign C for 120-min. Black-Right-Pointing-Pointer The fusion enzyme was responsible for cellulose-binding capacity. Black-Right-Pointing-Pointer The fusion enzyme has an attractive applicant for enzyme immobilization. -- Abstract: To improve the thermal stability and cellulose-binding capacity of Cryptococcus sp. S-2 lipase (CSLP), the cellulose-binding domain originates from Trichoderma reesei cellobiohydrolase I was engineered into C-terminal region of the CSLP (CSLP-CBD). The CSLP and CSLP-CBD were successfully expressed in the Pichia pastoris using the strong methanol inducible alcohol oxidase 1 (AOX1) promoter and the secretion signal sequence from Saccharomyces cerevisiae ({alpha} factor). The recombinant CSLP and CSLP-CBD were secreted into culture medium and estimated by SDS-PAGE to be 22 and 27 kDa, respectively. The fusion enzyme was stable at 80 Degree-Sign C and retained more than 80% of its activity after 120-min incubation at this temperature. Our results also found that the fusion of fungal exoglucanase cellulose-binding domain to CSLP is responsible for cellulose-binding capacity. This attribute should make it an attractive applicant for enzyme immobilization.

  6. Interactive Effects of Climate Change and Decomposer Communities on the Stabilization of Wood-Derived Carbon Pools: Catalyst for a New Study

    SciTech Connect

    Resh, Sigrid C.

    2014-11-17

    Globally, forest soils store ~two-thirds as much carbon (C) as the atmosphere. Although wood makes up the majority of forest biomass, the importance of wood contributions to soil C pools is unknown. Even with recent advances in the mechanistic understanding of soil processes, integrative studies tracing C input pathways and biological fluxes within and from soils are lacking. Therefore, our research objectives were to assess the impact of different fungal decay pathways (i.e., white-rot versus brown-rot)—in interaction with wood quality, soil temperature, wood location (i.e., soil surface and buried in mineral soil), and soil texture—on the transformation of woody material into soil CO2 efflux, dissolved organic carbon (DOC), and soil C pools. The use of 13C-depleted woody biomass harvested from the Rhinelander, WI free-air carbon dioxide enrichment (Aspen-FACE) experiment affords the unique opportunity to distinguish the wood-derived C from other soil C fluxes and pools. We established 168 treatment plots across six field sites (three sand and three loam textured soil). Treatment plots consisted of full-factorial design with the following treatments: 1. Wood chips from elevated CO2, elevated CO2 + O3, or ambient atmosphere AspenFACE treatments; 2. Inoculated with white rot (Bjerkandera adusta) or brown rot (Gloeophyllum sepiarium) pure fungal cultures, or the original suite of endemic microbial community on the logs; and 3. Buried (15cm in soil as a proxy for coarse roots) or surface applied wood chips. We also created a warming treatment using open-topped, passive warming chambers on a subset of the above treatments. Control plots with no added wood (“no chip control”) were incorporated into the research design. Soils were sampled for initial δ13C values, CN concentrations, and bulk density. A subset of plots were instrumented with lysimeters for sampling soil water and temperature data loggers for measuring soil temperatures. To determine the early

  7. Examining Temporal Stability of Scale Validity in Longitudinal Studies

    ERIC Educational Resources Information Center

    Raykov, Tenko

    2006-01-01

    A method for examining invariance in validity of multiple-component instruments in repeated measure designs is outlined. The approach is developed within the framework of covariance structure modeling and is applicable for purposes of ascertaining temporal stability in scale validity. In addition, the procedure provides a range of plausible values…

  8. Specific Sequestering Agents for the Actinides. 29. Stability of the Thorium(IV) Complexes of Desferrioxamine B (DFO) and Three Octadentate Catecholate or Hydroxypyridinonate DFO Derivatives: DFOMTA, DFOCAMC, and DFO-1,2-HOPO. Comparative Stability of the Plutonium(IV) DFOMTA Complex(1).

    PubMed

    Whisenhunt, Donald W.; Neu, Mary P.; Hou, Zhiguo; Xu, Jide; Hoffman, Darleane C.; Raymond, Kenneth N.

    1996-07-01

    The metal complex stability constants of Th(IV) with desferrioxamine B (DFO) and three octadentate derivatives [N-(2,3-dihydroxy-4-carboxybenzoyl)desferrioxamine B (DFOCAMC), N-(1,2-dihydro-1-hydroxy-2-oxopyridin-6-yl)carbonyl)desferrioxamine B (DFO-1,2-HOPO) and N-(2,3-dihydroxy-4-(methylamido)benzoyl)desferrioxamine B (DFOMTA)] have been determined. The formation constant of the Pu(IV)/DFOMTA complex has also been determined, and the formation constants have been estimated for the other Pu(IV) complexes of octadentate DFO derivatives. The DFO derivatives form 1:1 complexes with Th(IV) in aqueous solution. The solution chemistry of the Th(IV) complexes has been studied by spectrophotometric, potentiometric and proton NMR titrations. The Th(IV) formation constants are as follows (log K(f) values and esd's): DFO, 26.6(1); DFOMTA, 38.55(5); DFOCAMC, 37.2(3); DFO-1,2-HOPO, 33.7(4). The Pu(IV)/DFOMTA formation constant, determined by competitive spectrophotometric titration is (log K(f) value) 41.7(2). The estimation of the other Pu(IV) formation constants are as follows (log K(f) values): DFOCAMC, 40.4; DFO-1,2-HOPO, 36.9. The selectivity of DFO and the three derivatives for actinide(IV) ions is discussed. PMID:11666621

  9. Exposures to Airborne Particulate Matter and Adverse Perinatal Outcomes: A Biologically Plausible Mechanistic Framework for Exploring Potential Effect Modification by Nutrition

    PubMed Central

    Kannan, Srimathi; Misra, Dawn P; Dvonch, J. Timothy; Krishnakumar, Ambika

    2006-01-01

    Objectives The specific objectives are threefold: to describe the biologically plausible mechanistic pathways by which exposure to particulate matter (PM) may lead to the adverse perinatal outcomes of low birth weight (LBW), intrauterine growth retardation (IUGR), and preterm delivery (PTD); review the evidence showing that nutrition affects the biologic pathways; and explain the mechanisms by which nutrition may modify the impact of PM exposure on perinatal outcomes. Methods We propose an interdisciplinary conceptual framework that brings together maternal and infant nutrition, air pollution exposure assessment, and cardiopulmonary and perinatal epidemiology. Five possible albeit not exclusive biologic mechanisms have been put forth in the emerging environmental sciences literature and provide corollaries for the proposed framework. Conclusions Protecting the environmental health of mothers and infants remains a top global priority. The existing literature indicates that the effects of PM on LBW, PTD, and IUGR may manifest through the cardiovascular mechanisms of oxidative stress, inflammation, coagulation, endothelial function, and hemodynamic responses. PM exposure studies relating mechanistic pathways to perinatal outcomes should consider the likelihood that biologic responses and adverse birth outcomes may be derived from both PM and non-PM sources (e.g., nutrition). In the concluding section, we present strategies for empirically testing the proposed model and developing future research efforts. PMID:17107846

  10. Homocysteine in renovascular complications: hydrogen sulfide is a modulator and plausible anaerobic ATP generator

    PubMed Central

    Sen, Utpal; Pushpakumar, Sathnur B.; Amin, Matthew A.; Tyagi, Suresh C.

    2014-01-01

    Homocysteine (Hcy) is a non-protein amino acid derived from dietary methionine. High levels of Hcy, known as hyperhomocysteinemia (HHcy) is known to cause vascular complications. In the mammalian tissue, Hcy is metabolized by transsulfuration enzymes to produce hydrogen sulfide (H2S). H2S, a pungent smelling gas was previously known for its toxic effects in the central nervous system, recent studies however has revealed protective effects in a variety of diseases including hypertension, diabetes, inflammation, atherosclerosis, and renal disease progression and failure. Interestingly, under stress conditions including hypoxia, H2S can reduce metabolic demand and also act as a substrate for ATP production. This review highlights some of the recent advances in H2S research as a potential therapeutic agent targeting renovascular diseases associated with HHcy. PMID:24963795

  11. On the Plausibility of Pseudosugar Formation in Cometary Ices and Oxygen-rich Tholins

    NASA Astrophysics Data System (ADS)

    Lavado, Nieves; Ávalos, Martín; Babiano, Reyes; Cintas, Pedro; Light, Mark E.; Jiménez, José Luis; Palacios, Juan C.

    2016-03-01

    We revisit herein the formation and structure of dihydroxy dioxanes, which can be obtained from prebiotically available precursors and can be regarded as primeval sugar surrogates. Previous studies dealing with the heterogeneous composition of interstellar bodies point to the existence of significant amounts of small polyalcohols along with oxygen-containing oligomers. Even though such derivatives did not give rise to nucleosides and oligonucleotides, nor they were incorporated into subsequent metabolic routes, molecular chimeras based on sugar-like species could be opportunistic scaffolds in pre-evolutionary scenarios. We could figure out that pseudosugars, assembled by hemiacetalic bonds from available precursors in both interstellar and terrestrial scenarios, were presumably more abundant than thought. Moreover, these species share some key features with naturally-occurring sugar rings, such as anomeric preferences, coordinating ability, and the prevalent occurrence of racemic compounds.

  12. On the Plausibility of Pseudosugar Formation in Cometary Ices and Oxygen-rich Tholins.

    PubMed

    Lavado, Nieves; Ávalos, Martín; Babiano, Reyes; Cintas, Pedro; Light, Mark E; Jiménez, José Luis; Palacios, Juan C

    2016-03-01

    We revisit herein the formation and structure of dihydroxy dioxanes, which can be obtained from prebiotically available precursors and can be regarded as primeval sugar surrogates. Previous studies dealing with the heterogeneous composition of interstellar bodies point to the existence of significant amounts of small polyalcohols along with oxygen-containing oligomers. Even though such derivatives did not give rise to nucleosides and oligonucleotides, nor they were incorporated into subsequent metabolic routes, molecular chimeras based on sugar-like species could be opportunistic scaffolds in pre-evolutionary scenarios. We could figure out that pseudosugars, assembled by hemiacetalic bonds from available precursors in both interstellar and terrestrial scenarios, were presumably more abundant than thought. Moreover, these species share some key features with naturally-occurring sugar rings, such as anomeric preferences, coordinating ability, and the prevalent occurrence of racemic compounds. PMID:26428515

  13. A new simple /spl infin/OH neuron model as a biologically plausible principal component analyzer.

    PubMed

    Jankovic, M V

    2003-01-01

    A new approach to unsupervised learning in a single-layer neural network is discussed. An algorithm for unsupervised learning based upon the Hebbian learning rule is presented. A simple neuron model is analyzed. A dynamic neural model, which contains both feed-forward and feedback connections between the input and the output, has been adopted. The, proposed learning algorithm could be more correctly named self-supervised rather than unsupervised. The solution proposed here is a modified Hebbian rule, in which the modification of the synaptic strength is proportional not to pre- and postsynaptic activity, but instead to the presynaptic and averaged value of postsynaptic activity. It is shown that the model neuron tends to extract the principal component from a stationary input vector sequence. Usually accepted additional decaying terms for the stabilization of the original Hebbian rule are avoided. Implementation of the basic Hebbian scheme would not lead to unrealistic growth of the synaptic strengths, thanks to the adopted network structure. PMID:18238065

  14. Development and validation of a UHPLC-UV method for the determination of a prostate secretory protein 94-derived synthetic peptide (PCK3145) in human plasma and assessment of its stability in human plasma.

    PubMed

    El Mubarak, Mohamed A; Leontari, Iliana; Danika, Charikleia; Katsila, Theodora; Sivolapenko, Gregory

    2016-09-01

    PCK3145 is a synthetic peptide, derived from the Prostate Secreted Protein 94 (PSP94), with promising in vitro and animal in vivo results in prostate cancer. The aim of the present study was to develop and validate a fast and robust ultra-high-performance liquid chromatography with ultraviolet detection for the determination of PCK3145 in human plasma which would be suitable for the assessment of PCK3145 stability to proteolytic degradation. Following protein precipitation, chromatographic separation was carried out on an Aeris Peptide C18 column with mobile phase consisting of acetonitrile-water at a flow-rate of 0.50 mL/min. The calibration curve was linear over the range 0.50-20.00 μg/mL. Intra- and inter-day percentage relative standard deviation and relative error were ≤10%. The limit of detection and the lower limit of quantification were 0.15 and 0.50 μg/mL, respectively. Recovery of PCK3145 from human plasma was ≥96%. The peptide presented high stability in whole blood and in human plasma (>98% intact peptide after 24 h incubation at 37°C in human plasma), which represents a distinctive advantage in the therapeutic use of the compound. This is the first validated UHPLC method for the determination of PCK3145 reported, and it was successfully applied in the study of the proteolytic stability of PCK3145 in human plasma ex vivo. Copyright © 2016 John Wiley & Sons, Ltd. PMID:26892539

  15. Transplantation of adipose tissue-derived stem cells improves cardiac contractile function and electrical stability in a rat myocardial infarction model.

    PubMed

    Gautam, Milan; Fujita, Daiki; Kimura, Kazuhiro; Ichikawa, Hinako; Izawa, Atsushi; Hirose, Masamichi; Kashihara, Toshihide; Yamada, Mitsuhiko; Takahashi, Masafumi; Ikeda, Uichi; Shiba, Yuji

    2015-04-01

    The transplantation of adipose tissue-derived stem cells (ADSCs) improves cardiac contractility after myocardial infarction (MI); however, little is known about the electrophysiological consequences of transplantation. The purpose of this study was to clarify whether the transplantation of ADSCs increases or decreases the incidence of ventricular tachyarrhythmias (VT) in a rat model of MI. MI was induced experimentally by permanent occlusion of the left anterior descending artery of Lewis rats. ADSCs were harvested from GFP-transgenic rats, and were cultured until passage four. ADSCs (10×10(6)) resuspended in 100μL saline or pro-survival cocktail (PSC), which enhances cardiac graft survival, were injected directly into syngeneic rat hearts 1week after MI. The recipients of ADSCs suspended in PSC had a larger graft area compared with those receiving ASDCs suspended in saline at 1week post-transplantation (number of graft cells/section: 148.7±10.6 vs. 22.4±3.4, p<0.05, n=5/group). Thereafter, all ADSC recipients were transplanted with ASDCs in PSC. ADSCs were transplanted into infarcted hearts, and the mechanical and electrophysiological functions were assessed. Echocardiography revealed that ADSC recipients had improved contractile function compared with those receiving PSC vehicle (fractional shortening: 21.1±0.9 vs. 14.1±1.2, p<0.05, n≥12/group). Four weeks post-transplantation, VT was induced via in vivo programmed electrical stimulation. The recipients of ADSCs showed a significantly lower incidence of induced VT compared with the control (31.3% vs. 83.3%, p<0.05, n≥12/group). To understand the electrical activity following transplantation, we performed ex vivo optical mapping using a voltage sensitive dye, and found that ADSC transplantation decreased conduction velocity and its dispersion in the peri-infarct area. These results suggest that ADSC transplantation improved cardiac mechanical and electrophysiological functions in subacute MI. PMID

  16. Impact of soybean stover- and pine needle-derived biochars on Pb and As mobility, microbial community, and carbon stability in a contaminated agricultural soil.

    PubMed

    Ahmad, Mahtab; Ok, Yong Sik; Kim, Byung-Yong; Ahn, Jae-Hyung; Lee, Young Han; Zhang, Ming; Moon, Deok Hyun; Al-Wabel, Mohammad I; Lee, Sang Soo

    2016-01-15

    Biochar is gaining attention as a potential soil amendment to remediate and revitalize the contaminated soils. Simultaneous effects of biochar on metals mobility, microbial abundance, bacterial diversity and carbon storage in soil are scarcely addressed. This study assessed the effect of biochars on metal mobility, microbial abundance, bacterial community, and carbon storage in an agricultural soil contaminated with heavy metals. Biochars derived from soybean stover at 300 and 700 °C (S-BC300 and S-BC700, respectively) and pine needles at the same temperatures (P-BC300 and P-BC700, respectively) were used. A maximum reduction of Pb mobility by 95% was observed from a soil treated with S-BC700, associated with precipitation of chloropyromorphite and hydroxylpyromorphite. In contrast, As was desorbed from soil particles because of P competition. The abundance of Gram-positive and negative bacteria, fungi, actinomycetes, and arbuscular mycorrhizal fungi increased in the soils treated with biochar produced at 300 °C, possibly due to the high dissolved organic and active organic carbons. Microbial abundance in the soils treated with S-BC700 and P-BC700 was constant due to the existence of fixed or non-labile carbon. Changes to bacterial communities in the biochar-treated soils depended on feedstock type and pyrolysis temperature. Actinobacteria substantially increased whereas Acidobacteria and Chloroflexi decreased in the biochar-treated soils. The non-labile carbon fraction was ∼25 fold higher in the biochar-treated soil than the control soil, indicating long-term carbon storage. PMID:26496843

  17. Lack of Muc1-regulated beta-catenin stability results in aberrant expansion of CD11b+Gr1+ myeloid derived suppressor cells from the bone marrow

    PubMed Central

    Poh, Tze Wei; Bradley, Judy M.; Mukherjee, Pinku; Gendler, Sandra J.

    2009-01-01

    Myeloid Derived Suppressor Cells (MDSCs) are a heterogeneous population of myeloid cells that inhibit T cell activity and contribute to the immune suppression characteristic of most tumors. We discovered that bone marrow (BM) progenitor cells from the Muc1 knockout (KO) mice differentiated into CD11b+Gr1+ MDSCs in vitro under GM-CSF and IL-4 signaling. MUC1 is a tumor-associated mucin and its cytoplasmic tail (MUC1-CT) can regulate beta-catenin to promote oncogenesis. Given the importance of beta-catenin in hematopoiesis, we hypothesized that the MUC1 regulation of beta-catenin is important for MDSC development. Our current study shows that the aberrant development of BM progenitors into CD11b+Gr1+ MDSCs is dependent on the down regulation of beta-catenin levels that occurs in the absence of Muc1. In light of this, KO mice showed enhanced EL4 tumor growth and were able to better tolerate allogeneic BM185 tumor growth, with an accumulation of CD11b+Gr1+ cells in the blood and tumor draining lymph nodes. WT mice were able to similarly tolerate allogeneic tumor growth when they were injected with CD11b+Gr1+ cells from tumor-bearing KO mice, suggesting that tolerance of allogeneic tumors is dependent on MDSC-mediated immune suppression. This further delineates the ability of Muc1 to control MDSC development which could directly impact tumorigenesis. Knowledge of the biology by which Muc1 regulates the development of myeloid progenitors into MDSCs would also be very useful in enhancing the efficacy of cancer vaccines in the face of tumor immune suppression. PMID:19351842

  18. Infliximab is a plausible alternative for neurologic complications of Behçet disease

    PubMed Central

    Zeydan, Burcu; Uygunoglu, Ugur; Saip, Sabahattin; Demirci, Onat N.; Seyahi, Emire; Ugurlu, Serdal; Hamuryudan, Vedat; Siva, Aksel

    2016-01-01

    Objective: We evaluated the effectiveness of infliximab in patients with neuro-Behçet syndrome for whom other immunosuppressive medications had failed. Methods: Patients whose common immunosuppressive medications fail in recurrent neuro-Behçet syndrome need an alternative. We report our experience with the tumor necrosis factor α blocker infliximab for long-term treatment of neuro-Behçet syndrome. We recruited patients within a multidisciplinary referral practice of Behçet disease and prospectively followed everyone with a neurologic symptom(s). Patients (n = 16) with ≥2 neurologic bouts (excluding purely progressive disease) while on another immunosuppressive treatment were switched to and successfully sustained on infliximab (5 mg/kg in weeks 0, 2, and 6, then once every 8 weeks; minimum follow-up duration ≥12 months). Infliximab was stopped within 2 months after initiation in one patient because of pulmonary and CNS tuberculosis. Results: Patients had stepwise worsening due to relapses in the Expanded Disability Status Scale modified for neuro-Behçet syndrome before switching to infliximab (median score of 5.0, range 2.0–7.0; median neuro-Behçet syndrome duration 29.1 months, range 5.0–180.7). Median duration of preinfliximab immunosuppressive medication use was 20.0 months (range 3.0–180.7). In all 15 patients, during infliximab treatment (median score 4.0, range 2.0–7.0; median duration 39.0 months, range 16.0–104.9 months), neurologic relapses were completely aborted and there was no further disability accumulation. Conclusion: We observed a significant beneficial effect of infliximab in neuro-Behçet syndrome. Classification of evidence: This study provides Class IV evidence that for patients with neuro-Behçet syndrome whose other immunosuppressive medications failed, infliximab prevents further relapses and stabilizes disability. PMID:27458602

  19. A plausible radiobiological model of cardiovascular disease at low or fractionated doses

    NASA Astrophysics Data System (ADS)

    Little, Mark; Vandoolaeghe, Wendy; Gola, Anna; Tzoulaki, Ioanna

    Atherosclerosis is the main cause of coronary heart disease and stroke, the two major causes of death in developed society. There is emerging evidence of excess risk of cardiovascular disease at low radiation doses in various occupationally-exposed groups receiving small daily radia-tion doses. Assuming that they are causal, the mechanisms for effects of chronic fractionated radiation exposures on cardiovascular disease are unclear. We outline a spatial reaction-diffusion model for atherosclerosis, and perform stability analysis, based wherever possible on human data. We show that a predicted consequence of multiple small radiation doses is to cause mean chemo-attractant (MCP-1) concentration to increase linearly with cumulative dose. The main driver for the increase in MCP-1 is monocyte death, and consequent reduction in MCP-1 degradation. The radiation-induced risks predicted by the model are quantitatively consistent with those observed in a number of occupationally-exposed groups. The changes in equilibrium MCP-1 concentrations with low density lipoprotein cholesterol concentration are also consistent with experimental and epidemiologic data. This proposed mechanism would be experimentally testable. If true, it also has substantive implications for radiological protection, which at present does not take cardiovascular disease into account. The Japanese A-bomb survivor data implies that cardiovascular disease and can-cer mortality contribute similarly to radiogenic risk. The major uncertainty in assessing the low-dose risk of cardiovascular disease is the shape of the dose response relationship, which is unclear in the Japanese data. The analysis of the present paper suggests that linear extrapo-lation would be appropriate for this endpoint.

  20. Multiscale cosmology and structure-emerging dark energy: A plausibility analysis

    NASA Astrophysics Data System (ADS)

    Wiegand, Alexander; Buchert, Thomas

    2010-07-01

    Cosmological backreaction suggests a link between structure formation and the expansion history of the Universe. In order to quantitatively examine this connection, we dynamically investigate a volume partition of the Universe into over- and underdense regions. This allows us to trace structure formation using the volume fraction of the overdense regions λM as its characterizing parameter. Employing results from cosmological perturbation theory and extrapolating the leading mode into the nonlinear regime, we construct a three-parameter model for the effective cosmic expansion history, involving λM0, the matter density ΩmD0, and the Hubble rate HD0 of today’s Universe. Taking standard values for ΩmD0 and HD0 as well as a reasonable value for λM0, that we derive from N-body simulations, we determine the corresponding amounts of backreaction and spatial curvature. We find that the obtained values that are sufficient to generate today’s structure also lead to a ΛCDM-like behavior of the scale factor, parametrized by the same parameters ΩmD0 and HD0, but without a cosmological constant. However, the temporal behavior of λM does not faithfully reproduce the structure formation history. Surprisingly, however, the model matches with structure formation with the assumption of a low matter content, ΩmD0≈3%, a result that hints to a different interpretation of part of the backreaction effect as kinematical dark matter. A complementary investigation assumes the ΛCDM fit-model for the evolution of the global scale factor by imposing a global replacement of the cosmological constant through backreaction, and also supposes that a Newtonian simulation of structure formation provides the correct volume partition into over- and underdense regions. From these assumptions we derive the corresponding evolution laws for backreaction and spatial curvature on the partitioned domains. We find the correct scaling limit predicted by perturbation theory, which allows us to

  1. Plausible ``faster-than-light'' displacements in a two-sheeted spacetime

    NASA Astrophysics Data System (ADS)

    Petit, Fabrice; Sarrazin, Michaël

    2007-10-01

    In this paper, we explore the implications of a two-point discretization of an extra dimension in a five-dimensional quantum setup. We adopt a pragmatic attitude by considering the dynamics of spin-half particles through the simplest possible extension of the existing Dirac and Pauli equations. It is shown that the benefit of this approach is to predict new physical phenomena while maintaining the number of constitutive hypotheses at minimum. As the most striking feature of the model, we demonstrate the possibility of fermionic matter oscillations between the two four-dimensional sections and hyperfast displacements in case of asymmetric warping (without conflicting special relativity). This result, similar to previous reported ones in braneworld theories, is completely original as it is derived by using quantum mechanics only without recourse to general relativity and bulk geodesics calculation. The model allows causal contact between normally disconnected regions. If it proves to be physically founded, its practical aspects could have deep implications for the search of extra dimensions.

  2. Modeling SHARAD Echoes from HiRISE-Derived Stratigraphy of the Northern Polar Layered Deposits of Mars

    NASA Astrophysics Data System (ADS)

    Nunes, D. C.; Christian, S.; Holt, J. W.; Smrekar, S. E.; Phillips, R. J.

    2011-03-01

    We apply HiRISE-derived stratigraphy to propagation models and investigate plausible compositions of ice and dust. Initial results show reflections to have similar spacing (~30 m) as the separation of visual maker beds.

  3. Stabilization of asphaltenes in aliphatic solvents using alkylbenzene-derived amphiphiles. 2. Study of the asphaltene-amphiphile interactions and structures using Fourier transform infrared spectroscopy and small-angle X-ray scattering techniques

    SciTech Connect

    Chang, C.L.; Fogler, H.S. )

    1994-06-01

    In the preceding paper in this issue, the influence of the chemical structure of a series of alkylbenzene-derived amphiphiles on the stabilization of asphaltenes was described. In this paper, we present the results of using Fourier transform infrared (FTIR) spectroscopy and small-angle X-ray scattering (SAXS) techniques to study the interaction between asphaltenes and two alkylbenzene-derived amphiphiles, p-alkylphenol and p-alkylbenzenesulfonic acid. FTIR spectroscopy was used to characterize and quantify the acid-base interactions between asphaltenes and amphiphiles. It was found that asphaltenes could hydrogen-bond to p-dodecylphenol amphiphiles. The hydrogen-bonding capacity of asphaltenes was estimated to be 1.6-2.0 mmol/g of asphaltene. On the other hand, the FTIR spectroscopic study indicated that asphaltenes had a complicated acid-base interaction with p-dodecylbenzenesulfonic acid (DBSA) amphiphiles with a stoichiometry of about 1.8 mmol of DBSA/g of asphaltene. The UV/vis spectroscopic study suggested that asphaltenes and DBSA could associate into large electronic conjugated complexes. Physical evidence of the association between asphaltenes and amphiphiles was obtained by SAXS measurements. 27 refs., 10 figs.

  4. The potential role of homocysteine in percutaneous coronary interventions (PCI): review of current evidence and plausibility of action.

    PubMed

    Stanger, O

    2004-12-01

    Several millions of patients with coronary heart disease worldwide are treated by means ofpercutaneous interventions each year. Above all conventional balloon dilation and implantation of uncoated stents are, however, only of limited success as reflected by 6-month restenosis rates of 50% (balloon dilation) and 25-35% (bare-metal stent). It is therefore of utmost importance to identify high-risk groups and explore further secondary-prophylactic measures for the prevention of restenosis. A large body of evidence suggests that elevated homocysteine and/or folate and B-vitamin deficiencies are relevant risk factors for restenoses due to their proatherothrombotic potential. Hyperhomocysteinemia is an ideal target as this parameter can be lowered easily, safely and at a low cost by means of folate and B-vitamin supplementation. The results of published studies exploring a potential correlation between homocysteine levels and the risk of restenosis and those of interventional studies for the reduction of the risk of restenosis have not yet lead to consistent conclusions. However, a critical assessment can by no means exclude the plausibility of postinterventional lowering of homocysteine levels. This review aims at providing insight into the current evidence and biological plausibility of homocysteine-lowering therapy in regard to PCI-related vascular damage. Currently available clinical observational and interventional studies are reviewed in detail. PMID:15704259

  5. Antimicrobial drug use in Austrian pig farms: plausibility check of electronic on-farm records and estimation of consumption

    PubMed Central

    Trauffler, M.; Griesbacher, A.; Fuchs, K.; Köfer, J.

    2014-01-01

    Electronic drug application records from farmers from 75 conventional pig farms were revised and checked for their plausibility. The registered drug amounts were verified by comparing the farmers' records with veterinarians' dispensary records. The antimicrobial consumption was evaluated from 2008 to 2011 and expressed in weight of active substance(s), number of used daily doses (nUDD), number of animal daily doses (nADD) and number of product-related daily doses (nPrDD). All results were referred to one year and animal bodyweight (kg biomass). The data plausibility proof revealed about 14 per cent of unrealistic drug amount entries in the farmers' records. The annual antimicrobial consumption was 33.9 mg/kg/year, 4.9 UDDkg/kg/year, 1.9 ADDkg/kg/year and 2.5 PrDDkg/kg/year (average). Most of the antimicrobials were applied orally (86 per cent) and at group-level. Main therapy indications were metaphylactic/prophylactic measures (farrow-to-finish and fattening farms) or digestive tract diseases (breeding farms). The proportion of the ‘highest priority critically important antimicrobials’ was low (12 per cent). After determination of a threshold value, farms with a high antimicrobial use could be detected. Statistical tests showed that the veterinarian had an influence on the dosage, the therapy indication and the active substance. Orally administered antimicrobials were mostly underdosed, parenterally administered antimicrobials rather correctly or overdosed. PMID:25053268

  6. Ionic liquid pretreatment of biomass for sugars production: Driving factors with a plausible mechanism for higher enzymatic digestibility.

    PubMed

    Raj, Tirath; Gaur, Ruchi; Dixit, Pooja; Gupta, Ravi P; Kagdiyal, V; Kumar, Ravindra; Tuli, Deepak K

    2016-09-20

    In this study, five ionic liquids (ILs) have been explored for biomass pretreatment for the production of fermentable sugar. We also investigated the driving factors responsible for improved enzymatic digestibility of various ILs treated biomass along with postulating the plausible mechanism thereof. Post pretreatment, mainly two factors impacted the enzymatic digestibility (i) structural deformation (cellulose I to II) along with xylan/lignin removal and (ii) properties of ILs; wherein, K-T parameters, viscosity and surface tension had a direct influence on pretreatment. A systematic investigation of these parameters and their impact on enzymatic digestibility is drawn. [C2mim][OAc] with β-value 1.32 resulted 97.7% of glucose yield using 10 FPU/g of biomass. A closer insight into the cellulose structural transformation has prompted a plausible mechanism explaining the better digestibility. The impact of these parameters on the digestibility can pave the way to customize the process to make biomass vulnerable to enzymatic attack. PMID:27261761

  7. Learning and stabilization of winner-take-all dynamics through interacting excitatory and inhibitory plasticity

    PubMed Central

    Binas, Jonathan; Rutishauser, Ueli; Indiveri, Giacomo; Pfeiffer, Michael

    2014-01-01

    Winner-Take-All (WTA) networks are recurrently connected populations of excitatory and inhibitory neurons that represent promising candidate microcircuits for implementing cortical computation. WTAs can perform powerful computations, ranging from signal-restoration to state-dependent processing. However, such networks require fine-tuned connectivity parameters to keep the network dynamics within stable operating regimes. In this article, we show how such stability can emerge autonomously through an interaction of biologically plausible plasticity mechanisms that operate simultaneously on all excitatory and inhibitory synapses of the network. A weight-dependent plasticity rule is derived from the triplet spike-timing dependent plasticity model, and its stabilization properties in the mean-field case are analyzed using contraction theory. Our main result provides simple constraints on the plasticity rule parameters, rather than on the weights themselves, which guarantee stable WTA behavior. The plastic network we present is able to adapt to changing input conditions, and to dynamically adjust its gain, therefore exhibiting self-stabilization mechanisms that are crucial for maintaining stable operation in large networks of interconnected subunits. We show how distributed neural assemblies can adjust their parameters for stable WTA function autonomously while respecting anatomical constraints on neural wiring. PMID:25071538

  8. A Complex of Cas Proteins 5, 6, and 7 Is Required for the Biogenesis and Stability of Clustered Regularly Interspaced Short Palindromic Repeats (CRISPR)-derived RNAs (crRNAs) in Haloferax volcanii*

    PubMed Central

    Brendel, Jutta; Stoll, Britta; Lange, Sita J.; Sharma, Kundan; Lenz, Christof; Stachler, Aris-Edda; Maier, Lisa-Katharina; Richter, Hagen; Nickel, Lisa; Schmitz, Ruth A.; Randau, Lennart; Allers, Thorsten; Urlaub, Henning; Backofen, Rolf; Marchfelder, Anita

    2014-01-01

    The clustered regularly interspaced short palindromic repeats/CRISPR-associated (CRISPR-Cas) system is a prokaryotic defense mechanism against foreign genetic elements. A plethora of CRISPR-Cas versions exist, with more than 40 different Cas protein families and several different molecular approaches to fight the invading DNA. One of the key players in the system is the CRISPR-derived RNA (crRNA), which directs the invader-degrading Cas protein complex to the invader. The CRISPR-Cas types I and III use the Cas6 protein to generate mature crRNAs. Here, we show that the Cas6 protein is necessary for crRNA production but that additional Cas proteins that form a CRISPR-associated complex for antiviral defense (Cascade)-like complex are needed for crRNA stability in the CRISPR-Cas type I-B system in Haloferax volcanii in vivo. Deletion of the cas6 gene results in the loss of mature crRNAs and interference. However, cells that have the complete cas gene cluster (cas1–8b) removed and are transformed with the cas6 gene are not able to produce and stably maintain mature crRNAs. crRNA production and stability is rescued only if cas5, -6, and -7 are present. Mutational analysis of the cas6 gene reveals three amino acids (His-41, Gly-256, and Gly-258) that are essential for pre-crRNA cleavage, whereas the mutation of two amino acids (Ser-115 and Ser-224) leads to an increase of crRNA amounts. This is the first systematic in vivo analysis of Cas6 protein variants. In addition, we show that the H. volcanii I-B system contains a Cascade-like complex with a Cas7, Cas5, and Cas6 core that protects the crRNA. PMID:24459147

  9. The role of adverse childhood experiences in cardiovascular disease risk: a review with emphasis on plausible mechanisms.

    PubMed

    Su, Shaoyong; Jimenez, Marcia P; Roberts, Cole T F; Loucks, Eric B

    2015-10-01

    Childhood adversity, characterized by abuse, neglect, and household dysfunction, is a problem that exerts a significant impact on individuals, families, and society. Growing evidence suggests that adverse childhood experiences (ACEs) are associated with health decline in adulthood, including cardiovascular disease (CVD). In the current review, we first provide an overview of the association between ACEs and CVD risk, with updates on the latest epidemiological evidence. Second, we briefly review plausible pathways by which ACEs could influence CVD risk, including traditional risk factors and novel mechanisms. Finally, we highlight the potential implications of ACEs in clinical and public health. Information gleaned from this review should help physicians and researchers in better understanding potential long-term consequences of ACEs and considering adapting current strategies in treatment or intervention for patients with ACEs. PMID:26289252

  10. Climate Change Impacts on Agriculture and Food Security in 2050 under a Range of Plausible Socioeconomic and Emissions Scenarios

    NASA Astrophysics Data System (ADS)

    Wiebe, K.; Lotze-Campen, H.; Bodirsky, B.; Kavallari, A.; Mason-d'Croz, D.; van der Mensbrugghe, D.; Robinson, S.; Sands, R.; Tabeau, A.; Willenbockel, D.; Islam, S.; van Meijl, H.; Mueller, C.; Robertson, R.

    2014-12-01

    Previous studies have combined climate, crop and economic models to examine the impact of climate change on agricultural production and food security, but results have varied widely due to differences in models, scenarios and data. Recent work has examined (and narrowed) these differences through systematic model intercomparison using a high-emissions pathway to highlight the differences. New work extends that analysis to cover a range of plausible socioeconomic scenarios and emission pathways. Results from three general circulation models are combined with one crop model and five global economic models to examine the global and regional impacts of climate change on yields, area, production, prices and trade for coarse grains, rice, wheat, oilseeds and sugar to 2050. Results show that yield impacts vary with changes in population, income and technology as well as emissions, but are reduced in all cases by endogenous changes in prices and other variables.

  11. Bethe-Heitler cascades as a plausible origin of hard spectra in distant TeV blazars

    NASA Astrophysics Data System (ADS)

    Zheng, Y. G.; Yang, C. Y.; Kang, S. J.

    2016-01-01

    Context. Very high-energy (VHE) γ-ray measurements of distant TeV blazars can be nicely explained by TeV spectra induced by ultra high-energy cosmic rays. Aims: We develop a model for a plausible origin of hard spectra in distant TeV blazars. Methods: In the model, the TeV emission in distant TeV blazars is dominated by two mixed components. The first is the internal component with the photon energy around 1 TeV produced by inverse Compton scattering of the relativistic electrons on the synchrotron photons (SSC) with a correction for extragalactic background light absorbtion and the other is the external component with the photon energy more than 1 TeV produced by the cascade emission from high-energy protons propagating through intergalactic space. Results: Assuming suitable model parameters, we apply the model to observed spectra of distant TeV blazars of 1ES 0229+200. Our results show that 1) the observed spectrum properties of 1ES 0229+200, especially the TeV γ-ray tail of the observed spectra, could be reproduced in our model and 2) an expected TeV γ-ray spectrum with photon energy >1 TeV of 1ES 0229+200 should be comparable with the 50-h sensitivity goal of the Cherenkov Telescope Array (CTA) and the differential sensitivity curve for the one-year observation with the Large High Altitude Air Shower Observatory (LHAASO). Conclusions: We argue that strong evidence for the Bethe-Heitler cascades along the line of sight as a plausible origin of hard spectra in distant TeV blazars could be obtained from VHE observations with CTA, LHAASO, HAWC, and HiSCORE.

  12. MOF-derived, N-doped, hierarchically porous carbon sponges as immobilizers to confine selenium as cathodes for Li-Se batteries with superior storage capacity and perfect cycling stability

    NASA Astrophysics Data System (ADS)

    Li, Zhaoqiang; Yin, Longwei

    2015-05-01

    Nitrogen-doped carbon sponges (NCS) composed of hierarchical microporous carbon layers are derived from metal organic frameworks (MOFs) via carbonization at high temperatures under Ar and NH3 flow. Se is impregnated into 0.4-0.55 nm micropores by melting-diffusion and infiltration methods. The confinement of Se within small-sized micropores of NCS efficiently prevents Se loss, and mesopores between carbon layers absorb a sufficient amount of electrolyte, as well as serve as cushion spaces for large volume changes during delithiation-lithiation processes. Nitrogen doping improves the electrical conductivity of carbon matrix and facilitates rapid charge transfer, making the carbon sponge a highway for charges involved in redox reactions. When serving as cathode materials for Li-Se batteries, the NCS/Se-50 composite with 50 wt% Se exhibits excellent cycling stability, superior rate capability and high coulombic efficiency. The cathode can exhibit 443.2 mA h g-1 at the 200th cycle with a coulombic efficiency of up to 99.9% at 0.5C (C = 675 mA h g-1), which leads to 0.031% capacity loss per cycle from 5th to 200th cycles. Even at a high rate of 5C, it can still retain 286.6 mA h g-1. The unique, large surface rod-like MOF-derived, N-doped carbon sponges with hierarchical porosity could be potential candidates in the related energy-storage systems.Nitrogen-doped carbon sponges (NCS) composed of hierarchical microporous carbon layers are derived from metal organic frameworks (MOFs) via carbonization at high temperatures under Ar and NH3 flow. Se is impregnated into 0.4-0.55 nm micropores by melting-diffusion and infiltration methods. The confinement of Se within small-sized micropores of NCS efficiently prevents Se loss, and mesopores between carbon layers absorb a sufficient amount of electrolyte, as well as serve as cushion spaces for large volume changes during delithiation-lithiation processes. Nitrogen doping improves the electrical conductivity of carbon matrix and

  13. The most plausible explanation of the cyclic period changes in close binaries: the case of the RS CVn-type binary WW Dra

    NASA Astrophysics Data System (ADS)

    Liao, W.-P.; Qian, S.-B.

    2010-07-01

    Cyclic period changes are a fairly common phenomenon in close binary systems and are usually explained as being caused either by the magnetic activity of one or both components or by the light travel time effect (LTTE) of a third body. We searched the orbital period changes in 182 EA-type (including the 101 Algol systems used by Hall), 43 EB-type and 53 EW-type binaries with known mass ratio and spectral type of the secondary component. We reproduced and improved the diagram in Hall according to the new collected data. Our plots do not support the conclusion derived by Hall that cyclic period changes are restricted to binaries having a secondary component with spectral type later than F5. The presence of period changes among systems with a secondary component of early type indicates that magnetic activity is one, but not the only, cause of the period variation. It is discovered that cyclic period changes, probably resulting from the presence of a third body, are more frequent in EW-type binaries among close systems. Therefore, the most plausible explanation of the cyclic period changes is the LTTE through the presence of a third body. Using the century-long historical record of the times of light minimum, we analysed the cyclic period change in the Algol binary WW Dra. It is found that the orbital period of the binary shows a ~112.2-yr cyclic variation with an amplitude of ~0.1977d. The cyclic oscillation can be attributed to the LTTE by means of a third body with a mass no less than 6.43Msolar. However, no spectral lines of the third body were discovered, indicating that it may be a candidate black hole. The third body is orbiting the binary at a distance closer than 14.4 au and may play an important role in the evolution of this system.

  14. MOF-derived, N-doped, hierarchically porous carbon sponges as immobilizers to confine selenium as cathodes for Li-Se batteries with superior storage capacity and perfect cycling stability.

    PubMed

    Li, Zhaoqiang; Yin, Longwei

    2015-06-01

    Nitrogen-doped carbon sponges (NCS) composed of hierarchical microporous carbon layers are derived from metal organic frameworks (MOFs) via carbonization at high temperatures under Ar and NH3 flow. Se is impregnated into 0.4-0.55 nm micropores by melting-diffusion and infiltration methods. The confinement of Se within small-sized micropores of NCS efficiently prevents Se loss, and mesopores between carbon layers absorb a sufficient amount of electrolyte, as well as serve as cushion spaces for large volume changes during delithiation-lithiation processes. Nitrogen doping improves the electrical conductivity of carbon matrix and facilitates rapid charge transfer, making the carbon sponge a highway for charges involved in redox reactions. When serving as cathode materials for Li-Se batteries, the NCS/Se-50 composite with 50 wt% Se exhibits excellent cycling stability, superior rate capability and high coulombic efficiency. The cathode can exhibit 443.2 mA h g(-1) at the 200(th) cycle with a coulombic efficiency of up to 99.9% at 0.5C (C = 675 mA h g(-1)), which leads to 0.031% capacity loss per cycle from 5(th) to 200(th) cycles. Even at a high rate of 5C, it can still retain 286.6 mA h g(-1). The unique, large surface rod-like MOF-derived, N-doped carbon sponges with hierarchical porosity could be potential candidates in the related energy-storage systems. PMID:25951942

  15. Forces Stabilizing Proteins

    PubMed Central

    Pace, C. Nick; Scholtz, J. Martin; Grimsley, Gerald R.

    2014-01-01

    The goal of this article is to summarize what has been learned about the major forces stabilizing proteins since the late 1980s when site-directed mutagenesis became possible. The following conclusions are derived from experimental studies of hydrophobic and hydrogen bonding variants. 1. Based on studies of 138 hydrophobic interaction variants in 11 proteins, burying a –CH2– group on folding contributes 1.1 ± 0.5 kcal/mol to protein stability. 2. The burial of nonpolar side chains contributes to protein stability in two ways: first, a term that depends on the removal of the side chains from water and, more importantly, the enhanced London dispersion forces that result from the tight packing in the protein interior. 3. Based on studies of 151 hydrogen bonding variants in 15 proteins, forming a hydrogen bond on folding contributes 1.1 ± 0.8 kcal/mol to protein stability. 4. The contribution of hydrogen bonds to protein stability is strongly context dependent. 5. Hydrogen bonds by side chains and peptide groups make similar contributions to protein stability. 6. Polar group burial can make a favorable contribution to protein stability even if the polar group is not hydrogen bonded. 7. Hydrophobic interactions and hydrogen bonds both make large contributions to protein stability. PMID:24846139

  16. Stabilizing a spinning Skylab.

    NASA Technical Reports Server (NTRS)

    Seltzer, S. M.; Justice, D. W.; Schweitzer, G.; Patel, J. S.

    1972-01-01

    This paper presents the results of a study of the dynamics of a spinning Skylab space station. The stability of motion of several simplified models with flexible appendages was investigated. A digital simulation model that more accurately portrays the complex Skylab vehicle is described, and simulation results are compared with analytically derived results.

  17. Stabilizing a spinning Skylab

    NASA Technical Reports Server (NTRS)

    Seltzer, S. M.; Patel, J. S.; Justice, D. W.; Schweitzer, G. E.

    1972-01-01

    The results are presented of a study of the dynamics of a spinning Skylab space station. The stability of motion of several simplified models with flexible appendages was investigated. A digital simulation model that more accurately portrays the complex Skylab vehicle is described, and simulation results are compared with analytically derived results.

  18. Plausible double inflation

    NASA Technical Reports Server (NTRS)

    Holman, Richard; Kolb, Edward W.; Vadas, Sharon L.; Wang, Yun

    1991-01-01

    It is likely that extended inflation is followed by an epoch of slowroll inflation. Such a sequence of events may lead to a very interesting perturbation spectrum with significant power on the scale of the transition between the extended and slowroll phase, superimposed upon a power-law spectrum with deviations from the Harrison-Zeldovich slope. Normalization of the spectra above and below the transition scale is expected to differ.

  19. Insolubilization process increases enzyme stability

    NASA Technical Reports Server (NTRS)

    Billingham, J.; Lyn, J.

    1971-01-01

    Enzymes complexed with polymeric matrices contain properties suggesting application to enzyme-controlled reactions. Stability of insolubilized enzyme derivatives is markedly greater than that of soluble enzymes and physical form of insolubilized enzymes is useful in column and batch processes.

  20. Calculation of the lateral-dynamic stability of aircraft

    NASA Technical Reports Server (NTRS)

    Raikh, A

    1952-01-01

    Graphs and formulas are given with the aid of which all the aerodynamic coefficients required for computing the lateral dynamic stability can be determined. A number of numerical examples are given for obtaining the stability derivatives and solving the characteristic-stability equation. Approximate formulas are derived with the aid of which rapid preliminary computations may be made and the stability coefficients corrected for certain modifications of the airplane. A derivation of the lateral-dynamic-stability equations is included.

  1. Slope stability and stabilization methods

    SciTech Connect

    Abramson, L.W.; Lee, T.S.; Boyce, G.M.; Sharma, S.S.

    1995-12-01

    Slope stability can be a major problem during the construction of surface facilities. Cutting into existing ground disturbs the mechanics of the surrounding area, which can result in landslides and rock falls. This practical reference gives you the comprehensive information you need for slope stability analysis, suitable methods of analysis with and without the use of computers, and examples of common stability problems and stabilization methods for cuts and fills. It includes detailed discussions of methods used in slope stability analysis, including the Ordinary Method of Slices, Simplified Janbu Method, Simplified Bishop Method, Spencer`s Method, other limit equilibrium methods, numerical methods, total stress analysis, effective stress analysis, and the use of computer programs to solve problems. Chapters include: General Slope Stability Concepts; Engineering Geology Principles; Groundwater Conditions; Geologic Site Exploration; Laboratory Testing Interpretation; Slope Stability Concepts; Slope Stabilization Methods; and Design, Construction and Maintenance.

  2. Evolutionary stability on graphs

    PubMed Central

    Ohtsuki, Hisashi; Nowak, Martin A.

    2008-01-01

    Evolutionary stability is a fundamental concept in evolutionary game theory. A strategy is called an evolutionarily stable strategy (ESS), if its monomorphic population rejects the invasion of any other mutant strategy. Recent studies have revealed that population structure can considerably affect evolutionary dynamics. Here we derive the conditions of evolutionary stability for games on graphs. We obtain analytical conditions for regular graphs of degree k > 2. Those theoretical predictions are compared with computer simulations for random regular graphs and for lattices. We study three different update rules: birth-death (BD), death-birth (DB), and imitation (IM) updating. Evolutionary stability on sparse graphs does not imply evolutionary stability in a well-mixed population, nor vice versa. We provide a geometrical interpretation of the ESS condition on graphs. PMID:18295801

  3. Factors Influencing the Decisions and Actions of Pilots and Air Traffic Controllers in Three Plausible NextGen Environments

    NASA Technical Reports Server (NTRS)

    Vu, Kim-Phuong L.; Strybel, Thomas Z.; Battiste, Vernol; Johnson, Walter

    2011-01-01

    In the current air traffic management (ATM) system, pilots and air traffic controllers have well-established roles and responsibilities: pilots fly aircraft and are concerned with energy management, fuel efficiency, and passenger comfort; controllers separate aircraft and are concerned with safety and management of traffic flows. Despite having different goals and obligations, both groups must be able to effectively communicate and interact with each other for the ATM system to work. This interaction will become even more challenging as traffic volume increases dramatically in the near future. To accommodate this increase, by 2025 the national air transportation system in the U.S. will go through a transformation that will modernize the ATM system and make it safer, more effective, and more efficient. This new system, NextGen, will change how pilots and controllers perform their tasks by incorporating advanced technologies and employing new procedures. It will also distribute responsibility between pilots, controllers and automation over such tasks as maintaining aircraft separation. The present chapter describes three plausible concepts of operations that allocate different ATM responsibilities to these groups. We describe how each concept changes the role of each operator and the types of decisions and actions performed by them.

  4. Near-infrared spectroscopy of 3:1 Kirkwood Gap asteroids II: Probable and plausible parent bodies; primitive and differentiated

    NASA Astrophysics Data System (ADS)

    Fieber-Beyer, Sherry K.; Gaffey, Michael J.

    2014-02-01

    The 3:1 Kirkwood Gap asteroids are a mineralogically diverse set of asteroids located in a region that delivers meteoroids into Earth-crossing orbits. Mineralogical characterizations of asteroids in/near the 3:1 Kirkwood Gap can be used as a tool to “map” conditions and processes in the early Solar System. The chronological studies of the meteorite types provide a “clock” for the relative timing of those events and processes. By identifying the source asteroids of particular meteorite types, the “map” and “clock” can be combined to provide a much more sophisticated understanding of the history and evolution of the late solar nebula and the early Solar System. A mineralogical assessment of twelve 3:1 Kirkwood Gap asteroids has been carried out using near-infrared spectral data obtained from 2010 to 2011 combined with visible spectral data (when available) to cover the spectral interval of 0.4-2.5 μm. Eight of these asteroids have surfaces with basaltic-type silicate assemblages, indicating at least partial melting within their parent bodies. Although HED-like mineralogies are present these objects exhibit subdued features indicating the presence of an additional phase (e.g., NiFe metal) or process (e.g., space weathering). Four of these asteroids appear to be ordinary chondrite assemblages. Three of these are plausibly linked to the probable H-chondrite parent body, (6) Hebe.

  5. The Maria asteroid family: Genetic relationships and a plausible source of mesosiderites near the 3:1 Kirkwood Gap

    NASA Astrophysics Data System (ADS)

    Fieber-Beyer, Sherry K.; Gaffey, Michael J.; Kelley, Michael S.; Reddy, Vishnu; Reynolds, Chalbeth M.; Hicks, Tony

    2011-06-01

    We present a mineralogical assessment of 12 Maria family asteroids, using near-infrared spectral data obtained over the years 2000-2009 combined with visible spectral data (when available) to cover the spectral interval of 0.4-2.5 μm. Our analysis indicates the Maria asteroid family, which is located adjacent to the chaotic region of the 3:1 Kirkwood Gap, appears to be a true genetic family composed of assemblages analogous to mesosiderite-type meteorites. Dynamical models by Farinella et al. (Farinella, P., Gunczi, R., Froeschlé, Ch., Froeschlé, C., [1993]. Icarus 101, 174-187) predict this region should supply meteoroids into Earth-crossing orbits. Thus, the Maria family is a plausible source of some or all of the mesosiderites in our meteorite collections. These individual asteroids were most likely once part of a larger parent object that was broken apart and dispersed. One of the Maria dynamical family members investigated, ((695) Bella), was found to be unrelated to the genetic Maria family members. The parameters of (695) Bella indicate an H-chondrite assemblage, and that Bella may be a sister or daughter of Asteroid (6) Hebe.

  6. Gene-ontology enrichment analysis in two independent family-based samples highlights biologically plausible processes for autism spectrum disorders

    PubMed Central

    Anney, Richard J L; Kenny, Elaine M; O'Dushlaine, Colm; Yaspan, Brian L; Parkhomenka, Elena; Buxbaum, Joseph D; Sutcliffe, James; Gill, Michael; Gallagher, Louise; Bailey§, Anthony J; Fernandez, Bridget A; Szatmari§, Peter; Scherer§, Stephen W; Patterson§, Andrew; Marshall, Christian R; Pinto, Dalila; Vincent, John B; Fombonne, Eric; Betancur§, Catalina; Delorme, Richard; Leboyer, Marion; Bourgeron, Thomas; Mantoulan, Carine; Roge, Bernadette; Tauber, Maïté; Freitag§, Christine M; Poustka, Fritz; Duketis, Eftichia; Klauck§, Sabine M; Poustka, Annemarie; Papanikolaou, Katerina; Tsiantis, John; Gallagher§, Louise; Gill§, Michael; Anney, Richard; Bolshakova, Nadia; Brennan, Sean; Hughes, Gillian; McGrath, Jane; Merikangas, Alison; Ennis§, Sean; Green, Andrew; Casey, Jillian P; Conroy, Judith M; Regan, Regina; Shah, Naisha; Maestrini§, Elena; Bacchelli, Elena; Minopoli, Fiorella; Stoppioni, Vera; Battaglia§, Agatino; Igliozzi, Roberta; Parrini, Barbara; Tancredi, Raffaella; Oliveira§, Guiomar; Almeida, Joana; Duque, Frederico; Vicente§, Astrid; Correia, Catarina; Magalhaes, Tiago R; Gillberg, Christopher; Nygren, Gudrun; Jonge, Maretha de; Van Engeland, Herman; Vorstman, Jacob AS; Wittemeyer, Kerstin; Baird, Gillian; Bolton, Patrick F; Rutter, Michael L; Green, Jonathan; Lamb, Janine A; Pickles, Andrew; Parr, Jeremy R; Couteur, Ann Le; Berney, Tom; McConachie, Helen; Wallace, Simon; Coutanche, Marc; Foley, Suzanne; White, Kathy; Monaco§, Anthony P; Holt, Richard; Farrar, Penny; Pagnamenta, Alistair T; Mirza, Ghazala K; Ragoussis, Jiannis; Sousa, Inês; Sykes, Nuala; Wing, Kirsty; Hallmayer§, Joachim; Cantor§, Rita M; Nelson, Stanley F; Geschwind§, Daniel H; Abrahams, Brett S; Volkmar, Fred; Pericak-Vance§, Margaret A; Cuccaro, Michael L; Gilbert, John; Cook§, Edwin H; Guter, Stephen J; Jacob, Suma; Nurnberger Jr§, John I; McDougle, Christopher J; Posey, David J; Lord, Catherine; Corsello, Christina; Hus, Vanessa; Buxbaum§, Joseph D; Kolevzon, Alexander; Soorya, Latha; Parkhomenko, Elena; Leventhal, Bennett L; Dawson, Geraldine; Vieland§, Veronica J; Hakonarson§, Hakon; Glessner, Joseph T; Kim, Cecilia; Wang, Kai; Schellenberg§, Gerard D; Devlin§, Bernie; Klei, Lamburtus; Minshew, Nancy; Sutcliffe§, James S; Haines§, Jonathan L; Lund, Sabata C; Thomson, Susanne; Yaspan, Brian L; Coon§, Hilary; Miller, Judith; McMahon, William M; Munson, Jeff; Estes, Annette; Wijsman§, Ellen M; Buxbaum, Joseph D; Sutcliffe, James; Gill, Michael; Gallagher, Louise

    2011-01-01

    Recent genome-wide association studies (GWAS) have implicated a range of genes from discrete biological pathways in the aetiology of autism. However, despite the strong influence of genetic factors, association studies have yet to identify statistically robust, replicated major effect genes or SNPs. We apply the principle of the SNP ratio test methodology described by O'Dushlaine et al to over 2100 families from the Autism Genome Project (AGP). Using a two-stage design we examine association enrichment in 5955 unique gene-ontology classifications across four groupings based on two phenotypic and two ancestral classifications. Based on estimates from simulation we identify excess of association enrichment across all analyses. We observe enrichment in association for sets of genes involved in diverse biological processes, including pyruvate metabolism, transcription factor activation, cell-signalling and cell-cycle regulation. Both genes and processes that show enrichment have previously been examined in autistic disorders and offer biologically plausibility to these findings. PMID:21522181

  7. A hitherto undescribed case of cerebellar ataxia as the sole presentation of thyrotoxicosis in a young man: a plausible association.

    PubMed

    Elhadd, Tarik Abdelkareim; Linton, Kathryn; McCoy, Caoihme; Saha, Subrata; Holden, Roger

    2014-01-01

    A 16-year-old male presented to hospital following an episode of unusual behavior on the football pitch, where he was witnessed as grossly ataxic by his teammates. The assessment demonstrated marked cerebellar signs on examination but no other neurological deficit. The investigation showed the evidence of biochemical thyrotoxicosis with free T4 at 37 pmol/L (normal reference range: 11-27) and thyrotropin (TSH) < 0.003 mU/L. Following admission, full investigations including computed tomographic brain scan with contrast, lumbar puncture with cerebrospinal fluid examination, magnetic resonance imaging, and magnetic resonance angiography did not reveal abnormalities. He was initiated on carbimazole 40 mg every day. Thyroid ultrasonography revealed a goiter with increased blood flow, and his thyroid antibodies showed positive thyroid peroxidase antibodies but negative TSH receptor antibodies. Electroencephalogram did not reveal any abnormalities. His neurological disability resolved completely after his thyroid function normalized. The association of cerebellar syndromes is well described with hypothyroidism; however, it is hitherto undescribed with thyrotoxicosis. The causal relationship is plausible because alternative etiologies were excluded, and the normalization of thyroid function with treatment was coupled with complete resolution of the neurological syndrome. Cerebellar syndromes may well be one of the presenting features of thyrotoxicosis, and this should be in the list of its differential diagnosis. PMID:25827703

  8. On Matrix Sampling and Imputation of Context Questionnaires with Implications for the Generation of Plausible Values in Large-Scale Assessments

    ERIC Educational Resources Information Center

    Kaplan, David; Su, Dan

    2016-01-01

    This article presents findings on the consequences of matrix sampling of context questionnaires for the generation of plausible values in large-scale assessments. Three studies are conducted. Study 1 uses data from PISA 2012 to examine several different forms of missing data imputation within the chained equations framework: predictive mean…

  9. X-RAY INVESTIGATION OF THE DIFFUSE EMISSION AROUND PLAUSIBLE {gamma}-RAY EMITTING PULSAR WIND NEBULAE IN KOOKABURRA REGION

    SciTech Connect

    Kishishita, Tetsuichi; Bamba, Aya; Uchiyama, Yasunobu

    2012-05-10

    We report on the results from Suzaku X-ray observations of the radio complex region called Kookaburra, which includes two adjacent TeV {gamma}-ray sources HESS J1418-609 and HESS J1420-607. The Suzaku observation revealed X-ray diffuse emission around a middle-aged pulsar PSR J1420-6048 and a plausible pulsar wind nebula (PWN) Rabbit with elongated sizes of {sigma}{sub X} = 1.'66 and {sigma}{sub X} = 1.'49, respectively. The peaks of the diffuse X-ray emission are located within the {gamma}-ray excess maps obtained by H.E.S.S. and the offsets from the {gamma}-ray peaks are 2.'8 for PSR J1420-6048 and 4.'5 for Rabbit. The X-ray spectra of the two sources were well reproduced by absorbed power-law models with {Gamma} = 1.7-2.3. The spectral shapes tend to become softer according to the distance from the X-ray peaks. Assuming the one-zone electron emission model as the first-order approximation, the ambient magnetic field strengths of HESS J1420-607 and HESS J1418-609 can be estimated as 3 {mu}G and 2.5 {mu}G, respectively. The X-ray spectral and spatial properties strongly support that both TeV sources are PWNe, in which electrons and positrons accelerated at termination shocks of the pulsar winds are losing their energies via the synchrotron radiation and inverse Compton scattering as they are transported outward.

  10. X-Ray Investigation of the Diffuse Emission around Plausible γ-Ray Emitting Pulsar Wind Nebulae in Kookaburra Region

    NASA Astrophysics Data System (ADS)

    Kishishita, Tetsuichi; Bamba, Aya; Uchiyama, Yasunobu; Tanaka, Yasuyuki; Takahashi, Tadayuki

    2012-05-01

    We report on the results from Suzaku X-ray observations of the radio complex region called Kookaburra, which includes two adjacent TeV γ-ray sources HESS J1418-609 and HESS J1420-607. The Suzaku observation revealed X-ray diffuse emission around a middle-aged pulsar PSR J1420-6048 and a plausible pulsar wind nebula (PWN) Rabbit with elongated sizes of σX = 1farcm66 and σX = 1farcm49, respectively. The peaks of the diffuse X-ray emission are located within the γ-ray excess maps obtained by H.E.S.S. and the offsets from the γ-ray peaks are 2farcm8 for PSR J1420-6048 and 4farcm5 for Rabbit. The X-ray spectra of the two sources were well reproduced by absorbed power-law models with Γ = 1.7-2.3. The spectral shapes tend to become softer according to the distance from the X-ray peaks. Assuming the one-zone electron emission model as the first-order approximation, the ambient magnetic field strengths of HESS J1420-607 and HESS J1418-609 can be estimated as 3 μG and 2.5 μG, respectively. The X-ray spectral and spatial properties strongly support that both TeV sources are PWNe, in which electrons and positrons accelerated at termination shocks of the pulsar winds are losing their energies via the synchrotron radiation and inverse Compton scattering as they are transported outward.

  11. Developing spatially explicit footprints of plausible land-use scenarios in the Santa Cruz Watershed, Arizona and Sonora

    USGS Publications Warehouse

    Norman, Laura M.; Feller, Mark; Villarreal, Miguel L.

    2012-01-01

    The SLEUTH urban growth model is applied to a binational dryland watershed to envision and evaluate plausible future scenarios of land use change into the year 2050. Our objective was to create a suite of geospatial footprints portraying potential land use change that can be used to aid binational decision-makers in assessing the impacts relative to sustainability of natural resources and potential socio-ecological consequences of proposed land-use management. Three alternatives are designed to simulate different conditions: (i) a Current Trends Scenario of unmanaged exponential growth, (ii) a Conservation Scenario with managed growth to protect the environment, and (iii) a Megalopolis Scenario in which growth is accentuated around a defined international trade corridor. The model was calibrated with historical data extracted from a time series of satellite images. Model materials, methodology, and results are presented. Our Current Trends Scenario predicts the footprint of urban growth to approximately triple from 2009 to 2050, which is corroborated by local population estimates. The Conservation Scenario results in protecting 46% more of the Evergreen class (more than 150,000 acres) than the Current Trends Scenario and approximately 95,000 acres of Barren Land, Crops, Deciduous Forest (Mesquite Bosque), Grassland/Herbaceous, Urban/Recreational Grasses, and Wetlands classes combined. The Megalopolis Scenario results also depict the preservation of some of these land-use classes compared to the Current Trends Scenario, most notably in the environmentally important headwaters region. Connectivity and areal extent of land cover types that provide wildlife habitat were preserved under the alternative scenarios when compared to Current Trends.

  12. Categorization and decision-making in a neurobiologically plausible spiking network using a STDP-like learning rule.

    PubMed

    Beyeler, Michael; Dutt, Nikil D; Krichmar, Jeffrey L

    2013-12-01

    Understanding how the human brain is able to efficiently perceive and understand a visual scene is still a field of ongoing research. Although many studies have focused on the design and optimization of neural networks to solve visual recognition tasks, most of them either lack neurobiologically plausible learning rules or decision-making processes. Here we present a large-scale model of a hierarchical spiking neural network (SNN) that integrates a low-level memory encoding mechanism with a higher-level decision process to perform a visual classification task in real-time. The model consists of Izhikevich neurons and conductance-based synapses for realistic approximation of neuronal dynamics, a spike-timing-dependent plasticity (STDP) synaptic learning rule with additional synaptic dynamics for memory encoding, and an accumulator model for memory retrieval and categorization. The full network, which comprised 71,026 neurons and approximately 133 million synapses, ran in real-time on a single off-the-shelf graphics processing unit (GPU). The network was constructed on a publicly available SNN simulator that supports general-purpose neuromorphic computer chips. The network achieved 92% correct classifications on MNIST in 100 rounds of random sub-sampling, which is comparable to other SNN approaches and provides a conservative and reliable performance metric. Additionally, the model correctly predicted reaction times from psychophysical experiments. Because of the scalability of the approach and its neurobiological fidelity, the current model can be extended to an efficient neuromorphic implementation that supports more generalized object recognition and decision-making architectures found in the brain. PMID:23994510

  13. Membrane stabilizer

    DOEpatents

    Mingenbach, William A.

    1988-01-01

    A device is provided for stabilizing a flexible membrane secured within a frame, wherein a plurality of elongated arms are disposed radially from a central hub which penetrates the membrane, said arms imposing alternately against opposite sides of the membrane, thus warping and tensioning the membrane into a condition of improved stability. The membrane may be an opaque or translucent sheet or other material.

  14. Stabilization strategies for unstable dynamics.

    PubMed

    Morasso, Pietro; Casadio, Maura; De Santis, Dalia; Nomura, Taishin; Rea, Francesco; Zenzeri, Jacopo

    2014-12-01

    The stabilization of the human standing posture was originally attributed to the stiffness of the ankle muscles but direct measurements of the ankle stiffness ruled out this hypothesis, leaving open the possibility for a feedback stabilization strategy driven by proprioceptive signals. This solution, however, could be implemented with two different kinds of control mechanisms, namely continuous or intermittent feedback. The debate is now settled and the latter solution seems to be the most plausible one. Moreover, stabilization of unstable dynamics is not limited to bipedal standing. Indeed many manipulation tasks can be described in the same framework and thus a very general protocol for addressing this kind of problems is the use of haptic virtual reality where instability is generated by some kind of divergent or saddle-like force field. Several studies demonstrated that human subjects can choose to adopt a stiffness or feedback strategy as a combination of biomechanical and task constraints and can learn to switch from one strategy to the other if it is feasible or to use one or the other is infeasible. Understanding such mechanisms is relevant, for example, for the design of novel ergonomic man-machine interfaces in difficult, unstable tasks. PMID:25453479

  15. Method for Studying Helicopter Longitudinal Maneuver Stability

    NASA Technical Reports Server (NTRS)

    Amer, Kenneth B

    1954-01-01

    A theoretical analysis of helicopter maneuver stability is made and the results are compared with experimental results for both a single and a tandem rotor helicopter. Techniques are described for measuring in flight the significant stability derivatives for use with the theory to aid in design studies of means for achieving marginal maneuver stability for a prototype helicopter.

  16. Jet Fuel Thermal Stability

    NASA Technical Reports Server (NTRS)

    Taylor, W. F. (Editor)

    1979-01-01

    Various aspects of the thermal stability problem associated with the use of broadened-specification and nonpetroleum-derived turbine fuels are addressed. The state of the art is reviewed and the status of the research being conducted at various laboratories is presented. Discussions among representatives from universities, refineries, engine and airframe manufacturers, airlines, the Government, and others are presented along with conclusions and both broad and specific recommendations for future stability research and development. It is concluded that significant additional effort is required to cope with the fuel stability problems which will be associated with the potentially poorer quality fuels of the future such as broadened specification petroleum fuels or fuels produced from synthetic sources.

  17. Automatic stabilization

    NASA Technical Reports Server (NTRS)

    Haus, FR

    1936-01-01

    This report concerns the study of automatic stabilizers and extends it to include the control of the three-control system of the airplane instead of just altitude control. Some of the topics discussed include lateral disturbed motion, static stability, the mathematical theory of lateral motion, and large angles of incidence. Various mechanisms and stabilizers are also discussed. The feeding of Diesel engines by injection pumps actuated by engine compression, achieves the required high speeds of injection readily and permits rigorous control of the combustible charge introduced into each cylinder and of the peak pressure in the resultant cycle.

  18. Food Fortification Stability Study

    NASA Technical Reports Server (NTRS)

    Abdulmalik, T. O.; Cooper, M. R.; Douglas, G. L.

    2015-01-01

    NASA has established the goal of traveling beyond low-Earth orbit and extending manned exploration to Mars. The extended length of a Mars mission, along with the lack of resupply missions increases the importance of nutritional content in the food system. The purpose of this research is to assess the stability of vitamin supplementation in traditionally processed spaceflight foods. It is expected that commercially available fortificants will remain stable through long-duration missions if proper formulation, processing, and storage temperatures are all achieved. Five vitamins (vitamin E, vitamin K, pantothenic acid, folic acid, and thiamin) were blended into a vitamin premix (DSM, Freeport, TX); premixes were formulated to be compatible with current processing techniques (retort or freeze-dried), varied water activities (high or low), and packaging material. The overall goal of this process is to provide 25% of the recommended daily intake of each vitamin (per serving), following processing and two years of ambient storage. Four freeze-dried foods (Scrambled Eggs, Italian Vegetables, Potatoes Au Gratin, Noodles and Chicken) and four thermostabilized foods (Curry Sauce with Vegetables, Chicken Noodle Soup, Grilled Pork Chop, Rice with Butter) were produced (with and without the vitamin premix), to assess the impact of the added fortificant on color and taste, and to determine the stability of supplemental vitamins in spaceflight foods. The use of fortification in spaceflight foods appears to be a plausible mitigation step to inadequate nutrition. This is due to the ease of vitamin addition as well as the sustainability of the premixes through initial processing steps. Postprocessing analysis indicated that vitamin fortification with this premix did not immediately impact organoleptic properties of the food. At this stage, the largest hurdle to fortification is the preciseness to which vitamins can be added; the total amount of vitamins required for production is 10

  19. Parathyroid hormone is a plausible mediator for the metabolic syndrome in the morbidly obese: a cross-sectional study

    PubMed Central

    2011-01-01

    indicate that for women PTH is a plausible mediator in the association between MS and a range of explanatory variables, including vit D, magnesium and phosphate. PMID:21306649

  20. Membrane stabilizer

    DOEpatents

    Mingenbach, W.A.

    1988-02-09

    A device is provided for stabilizing a flexible membrane secured within a frame, wherein a plurality of elongated arms are disposed radially from a central hub which penetrates the membrane, said arms imposing alternately against opposite sides of the membrane, thus warping and tensioning the membrane into a condition of improved stability. The membrane may be an opaque or translucent sheet or other material. 10 figs.

  1. Nighttime thermospheric meridional winds as inferred from ionosonde parameters over Indian region and their plausible effects on plasma irregularities

    NASA Astrophysics Data System (ADS)

    Sreekumar, Sreeba; Sripathi, S.

    2016-07-01

    In this paper, we present nighttime thermospheric meridional winds at Indian low latitude station namely Hyderabad during March-May 2013 derived using (a) h'F method and (b) hpF2 method based on ionosondes. The estimation of meridional winds using h'F method employs the basic principle that the vertical drift at magnetic equator is purely due to ExB drift, while for a station slightly away from magnetic equator, meridional wind also contributes for the vertical drift in addition to diffusion along the field lines. Assuming the EXB drifts are the same at both the locations, the vertical drift contribution is subtracted from the equatorial vertical drifts and then meridional winds are derived, whereas in hpF2 method, winds are derived using the SERVO theory. The winds so derived are compared with HWM07 wind model. The comparison suggests that magnitude of winds derived using h'F method are in better agreement with HWM07 model than hpF2 derived winds where their polarities are better comparable to HWM07 model than hpF2 method. The poor agreement of hpF2 method could be due to uncertainties involved in estimating various ionospheric parameters. Also the winds derived using h'F method showed signatures of the well known phenomenon of Midnight Temperature Maximum (MTM). Based on these results, we suggest that h'F method is better suited for meridional wind estimates over low latitudes than hpF2 method. Accordingly, we further investigated the role of thermospheric meridional winds in equatorial spread F (ESF) occurrence. Our results suggest that equatorward winds along with post sunset height increase could enhance the Rayleigh Taylor (RT) instability growth rate and thereby leading to the generation of ESF/scintillations. The Superposed Epoch Analysis (SEA) technique has been applied to understand the general trend of h'F and meridional winds around the ESF onset time. The study showed reduction in poleward winds, half an hour prior to the onset of ESF. Hence indicating

  2. Anisotropic higher derivative gravity and inflationary universe

    SciTech Connect

    Kao, W. F.

    2006-08-15

    Stability analysis of the Kantowski-Sachs type universe in pure higher derivative gravity theory is studied in detail. The nonredundant generalized Friedmann equation of the system is derived by introducing a reduced one-dimensional generalized Kantowski-Sachs type action. Existence and stability of inflationary solution in the presence of higher derivative terms are also studied in detail. Implications to the choice of physical theories are discussed in detail in this paper.

  3. Bipolar-pulses observed by the LRS/WFC-L onboard KAGUYA - Plausible evidence of lunar dust impact -

    NASA Astrophysics Data System (ADS)

    Kasahara, Yoshiya; Horie, Hiroki; Hashimoto, Kozo; Omura, Yoshiharu; Goto, Yoshitaka; Kumamoto, Atsushi; Ono, Takayuki; Tsunakawa, Hideo; Lrs/Wfc Team; Map/Lmag Team

    2010-05-01

    same) and thus most of bipolar-pulses which can be detected in MONO mode are cancelled in DIFF mode. This fact suggests that these bipolar pulses are not a kind of natural wave but these are caused by instantaneous potential changes of the KAGUYA spacecraft. Discussion: Similar type of bipolar-pulses has been observed by the monopole antenna measurements using Radio and Plasma Wave Science (RPWS) instruments on-board Cassini around Saturn [4]. They demonstrated that these bipolar pulses are caused by impacts of dusts floating around the Saturn. It is well-known that lunar dusts are widely dis-tributed in higher altitude range around the moon and it is plausible that these bipolar pulses are caused by the lunar dust impacts. In the presentation, we show the detailed charac-teristics of bipolar pulses detected by the WFC-L onboard KAGUYA. References: [1] Y. Kasahara et al., Earth, Planets and Space, 60(4), 341-351, 2008. [2] T. Ono et al., Earth, Planets and Space, 60(4), 321-332, 2008. [3] K. Hashimoto et al., The 4th SELENE (KAGUYA) Science Working Team Meeting, (this issue), 2010. [4] W.S. Kurth et al, Planetary and Space Science, 54(9-10), 988-998, 2006.

  4. The SAFRR Tsunami Scenario: Improving Resilience for California from a Plausible M9 Earthquake near the Alaska Peninsula

    NASA Astrophysics Data System (ADS)

    Ross, S.; Jones, L.; Wilson, R. I.; Bahng, B.; Barberopoulou, A.; Borrero, J. C.; Brosnan, D.; Bwarie, J.; Geist, E. L.; Johnson, L.; Kirby, S. H.; Knight, W.; Long, K.; Lynett, P. J.; Miller, K.; Mortensen, C. E.; Nicolsky, D.; Oglesby, D. D.; Perry, S. C.; Plumlee, G. S.; Porter, K. A.; Real, C. R.; Ryan, K. J.; Suleimani, E.; Thio, H. K.; Titov, V.; Wein, A. M.; Whitmore, P.; Wood, N. J.

    2013-12-01

    The SAFRR Tsunami Scenario models a hypothetical but plausible tsunami, created by an Mw9.1 earthquake occurring offshore from the Alaskan peninsula, and its impacts on the California coast. We present the likely inundation areas, current velocities in key ports and harbors, physical damage and repair costs, economic consequences, environmental impacts, social vulnerability, emergency management, and policy implications for California associated with the tsunami scenario. The intended users are those who must make mitigation decisions before and rapid decisions during future tsunamis. Around a half million people would be present in the scenario's inundation area in residences, businesses, public venues, parks and beaches. Evacuation would likely be ordered for the State of California's maximum mapped tsunami inundation zone, evacuating an additional quarter million people from residences and businesses. Some island and peninsula communities would face particular evacuation challenges because of limited access options and short warning time, caused by the distance between Alaska and California. Evacuations may also be a challenge for certain dependent-care populations. One third of the boats in California's marinas could be damaged or sunk, costing at least 700 million in repairs to boats and docks, and potentially much more to address serious issues due to sediment transport and environmental contamination. Fires would likely start at many sites where fuel and petrochemicals are stored in ports and marinas. Tsunami surges and bores may travel several miles inland up coastal rivers. Debris clean-up and recovery of inundated and damaged areas will take days, months, or years depending on the severity of impacts and the available resources for recovery. The Ports of Los Angeles and Long Beach (POLA/LB) would be shut down for a miniμm of two days due to strong currents. Inundation of dry land in the ports would result in 100 million damages to cargo and additional

  5. Connective stability of competitive equilibrium

    NASA Technical Reports Server (NTRS)

    Siljak, D. D.

    1975-01-01

    The purpose of this paper is to derive necessary and sufficient conditions for the connective stability of nonlinear matrix systems described by the equation x-dot = A(t, x) x, where the matrix A(t, x) has time-varying nonlinear elements. The results obtained can be used to study the stability of competitive equilibrium in fields as diverse as economics and engineering, model ecosystems, and the arms race.-

  6. Laser Stabilization

    SciTech Connect

    Hall, John L.; Taubman, Matthew S.; Ye, Jun

    2010-01-01

    This book chapter covers the basics of the field of stabilizing lasers to optical frequency references such as optical cavities and molecular transitions via the application of servo control systems. These discussions are given with reference to the real-life frequency metrology experienced in Hall-Labs (now Ye-Labs), JILA, University of Colorado. The subjects covered include: the basics of control system stability, a discussion of both the theoretical and experimental limitations, an outline of optical cavity susceptibility to environmental noise, and a brief introduction to the use and limitations of molecular transitions as frequency references.

  7. Stability of surface nanobubbles

    NASA Astrophysics Data System (ADS)

    Maheshwari, Shantanu; van der Hoef, Martin; Zhang, Xuehua; Lohse, Detlef

    2015-11-01

    We have studied the stability and dissolution of surface nanobubbles on the chemical heterogenous surface by performing Molecular Dynamics (MD) simulations of binary mixture consists of Lennard-Jones (LJ) particles. Recently our group has derived the exact expression for equilibrium contact angle of surface nanobubbles as a function of oversaturation of the gas concentration in bulk liquid and the lateral length of bubble. It has been showed that the contact line pinning and the oversaturation of gas concentration in bulk liquid is crucial in the stability of surface nanobubbles. Our simulations showed that how pinning of the three-phase contact line on the chemical heterogenous surface lead to the stability of the nanobubble. We have calculated the equilibrium contact angle by varying the gas concentration in bulk liquid and the lateral length of the bubble. Our results showed that the equilibrium contact angle follows the expression derived analytically by our group. We have also studied the bubble dissolution dynamics and showed the ''stick-jump'' mechanism which was also observed experimentally in case of dissolution of nanodrops.

  8. Visual stability

    PubMed Central

    Melcher, David

    2011-01-01

    Our vision remains stable even though the movements of our eyes, head and bodies create a motion pattern on the retina. One of the most important, yet basic, feats of the visual system is to correctly determine whether this retinal motion is owing to real movement in the world or rather our own self-movement. This problem has occupied many great thinkers, such as Descartes and Helmholtz, at least since the time of Alhazen. This theme issue brings together leading researchers from animal neurophysiology, clinical neurology, psychophysics and cognitive neuroscience to summarize the state of the art in the study of visual stability. Recently, there has been significant progress in understanding the limits of visual stability in humans and in identifying many of the brain circuits involved in maintaining a stable percept of the world. Clinical studies and new experimental methods, such as transcranial magnetic stimulation, now make it possible to test the causal role of different brain regions in creating visual stability and also allow us to measure the consequences when the mechanisms of visual stability break down. PMID:21242136

  9. Nonparallel stability of boundary layers

    NASA Technical Reports Server (NTRS)

    Nayfeh, Ali H.

    1987-01-01

    The asymptotic formulations of the nonparallel linear stability of incompressible growing boundary layers are critically reviewed. These formulations can be divided into two approaches. The first approach combines a numerical method with either the method of multiple scales, or the method of averaging, of the Wentzel-Kramers-Brillouin (WKB) approximation; all these methods yield the same result. The second approach combined a multi-structure theory with the method of multiple scales. The first approach yields results that are in excellent agreement with all available experimental data, including the growth rates as well as the neutral stability curve. The derivation of the linear stability of the incompressible growing boundary layers is explained.

  10. Dynamic stability of detached solidification

    NASA Astrophysics Data System (ADS)

    Mazuruk, K.; Volz, M. P.

    2016-06-01

    A dynamic stability analysis model is developed for meniscus-defined crystal growth processes. The Young-Laplace equation is used to analyze the response of a growing crystal to perturbations to its radius and a thermal transport model is used to analyze the effect of perturbations on the evolution of the crystal-melt interface. A linearized differential equation is used to analyze radius perturbations but a linear integro-differential equation is required for the height perturbations. The stability model is applied to detached solidification under zero-gravity and terrestrial conditions. A numerical analysis is supplemented with an approximate analytical analysis, valid in the limit of small Bond numbers. For terrestrial conditions, a singularity is found to exist in the capillary stability coefficients where, at a critical value of the pressure differential across the meniscus, there is a transition from stability to instability. For the zero-gravity condition, exact formulas for the capillary stability coefficients are derived.

  11. On the adiabatic stability of solitons and the matching of conservation laws

    NASA Astrophysics Data System (ADS)

    Lochak, Pierre

    1984-08-01

    We derive a series of identities which generalize and simplify the results obtained for adiabatically modulated solitons in the case of perturbed specific integrable equations. It stresses the importance of the variational properties of the solitons, which make an adiabatic theorem plausible. A precise conjecture is made and its validity discussed from different points of view.

  12. Stabilization of polyaniline solutions through additives

    DOEpatents

    Wrobleski, D.A.; Benicewicz, B.C.

    1996-12-10

    A stabilized non-conductive polyaniline solution comprising from about 1 to about 10 percent by weight polyaniline or a polyaniline derivative, from about 90 to about 99 percent by weight N-methylpyrrolidone, and from about 0.5 percent by weight to about 15 percent by weight of a solution stabilizing additive selected from the group consisting of hindered amine light stabilizers, polymeric amines, and dialkylamines, percent by weight of additive based on the total weight of polyaniline or polyaniline derivative is provided together with a method for stabilizing a polyaniline solution. 4 figs.

  13. On structural and lattice dynamic stability of LaF{sub 3} under high pressure: A first principle study

    SciTech Connect

    Sahoo, B. D. Joshi, K. D.; Gupta, Satish C.

    2015-06-24

    Structural and lattice dynamical stability of the LaF3 has been analyzed as a function of hydrostatic compression through first principle electronic band structure calculations. The comparison of enthalpies of various plausible structures calculated at various pressures suggests a phase transition from ambient condition tysonite structure (space group P-3c1) to a primitive orthorhombic structure (space group Pmmn) at a pressure of ∼19.5 GPa, in line with the experimental value of 16 GPa. Further, it is predicted that this phase will remain stable up to 100 GPa (the maximum pressure up to which calculations have been performed in the present work). The theoretically determined equation of state displays a good agreement with experimental data. Various physical quantities such as zero pressure equilibrium volume, bulk modulus, and pressure derivative of bulk modulus have been derived from the theoretically determined equation of state and compared with the available experimental data. Our lattice dynamic calculations correctly demonstrate that at zero pressure the tysonite structure is lattice dynamically stable whereas the Pmmn structure is unstable lattice dynamically. Further, at transition pressure the theoretically calculated phonon spectra clearly show that the Pmmn phase emerges as lattice dynamically stable phase whereas the tysonite structure becomes unstable dynamically, supporting our static lattice calculations.

  14. Effects of vertical fins near the nose of the fuselage on the directional and damping-in-yaw stability derivatives of an airplane model under steady-state and oscillatory conditions

    NASA Technical Reports Server (NTRS)

    Queijo, M J; Wells, Evalyn G

    1956-01-01

    A wind-tunnel investigation has been made at low speed to determine the effects of vertical fins placed ahead of the vertical tail on the directional stability and damping-in-yaw characteristics of a swept-wing model under steady-state oscillatory conditions. Various sizes of fins were used above and below the fuselage center line. The vertical-tail size also was varied.

  15. Summation by parts, projections, and stability

    NASA Technical Reports Server (NTRS)

    Olsson, Pelle

    1993-01-01

    We have derived stability results for high-order finite difference approximations of mixed hyperbolic-parabolic initial-boundary value problems (IBVP). The results are obtained using summation by parts and a new way of representing general linear boundary conditions as an orthogonal projection. By slightly rearranging the analytic equations, we can prove strict stability for hyperbolic-parabolic IBVP. Furthermore, we generalize our technique so as to yield strict stability on curvilinear non-smooth domains in two space dimensions. Finally, we show how to incorporate inhomogeneous boundary data while retaining strict stability. Using the same procedure one can prove strict stability in higher dimensions as well.

  16. One-pot synthesis of tetrazole-1,2,5,6-tetrahydronicotinonitriles and cholinesterase inhibition: Probing the plausible reaction mechanism via computational studies.

    PubMed

    Hameed, Abdul; Zehra, Syeda Tazeen; Abbas, Saba; Nisa, Riffat Un; Mahmood, Tariq; Ayub, Khurshid; Al-Rashida, Mariya; Bajorath, Jürgen; Khan, Khalid Mohammed; Iqbal, Jamshed

    2016-04-01

    In the present study, one-pot synthesis of 1H-tetrazole linked 1,2,5,6-tetrahydronicotinonitriles under solvent-free conditions have been carried out in the presence of tetra-n-butyl ammonium fluoride trihydrated (TBAF) as catalyst and solvent. Computational studies have been conducted to elaborate two plausible mechanistic pathways of this one-pot reaction. Moreover, the synthesized compounds were screened for cholinesterases (acetylcholinesterase and butyrylcholinesterase) inhibition which are consider to be major malefactors of Alzheimer's disease (AD) to find lead compounds for further research in AD therapy. PMID:26851737

  17. Stabilizing Pentacene By Cyclopentannulation.

    PubMed

    Bheemireddy, Sambasiva R; Ubaldo, Pamela C; Rose, Peter W; Finke, Aaron D; Zhuang, Junpeng; Wang, Lichang; Plunkett, Kyle N

    2015-12-21

    A new class of stabilized pentacene derivatives with externally fused five-membered rings are prepared by means of a key palladium-catalyzed cyclopentannulation step. The target compounds are synthesized by chemical manipulation of a partially saturated 6,13-dibromopentacene precursor that can be fully aromatized in a final step through a DDQ-mediated dehydrogenation reaction (DDQ=2,3-dichloro-5,6-dicyano-1,4-benzoquinone). The new 1,2,8,9-tetraaryldicyclopenta[fg,qr]pentacene derivatives have narrow energy gaps of circa 1.2 eV and behave as strong electron acceptors with lowest unoccupied molecular orbital energies between -3.81 and -3.90 eV. Photodegradation studies reveal the new compounds are more photostable than 6,13-bis(triisopropylsilylethynyl)pentacene (TIPS-pentacene). PMID:26768696

  18. Mutations in the KDM5C ARID Domain and Their Plausible Association with Syndromic Claes-Jensen-Type Disease

    PubMed Central

    Peng, Yunhui; Suryadi, Jimmy; Yang, Ye; Kucukkal, Tugba G.; Cao, Weiguo; Alexov, Emil

    2015-01-01

    Mutations in KDM5C gene are linked to X-linked mental retardation, the syndromic Claes-Jensen-type disease. This study focuses on non-synonymous mutations in the KDM5C ARID domain and evaluates the effects of two disease-associated missense mutations (A77T and D87G) and three not-yet-classified missense mutations (R108W, N142S, and R179H). We predict the ARID domain’s folding and binding free energy changes due to mutations, and also study the effects of mutations on protein dynamics. Our computational results indicate that A77T and D87G mutants have minimal effect on the KDM5C ARID domain stability and DNA binding. In parallel, the change in the free energy unfolding caused by the mutants A77T and D87G were experimentally measured by urea-induced unfolding experiments and were shown to be similar to the in silico predictions. The evolutionary conservation analysis shows that the disease-associated mutations are located in a highly-conserved part of the ARID structure (N-terminal domain), indicating their importance for the KDM5C function. N-terminal residues’ high conservation suggests that either the ARID domain utilizes the N-terminal to interact with other KDM5C domains or the N-terminal is involved in some yet unknown function. The analysis indicates that, among the non-classified mutations, R108W is possibly a disease-associated mutation, while N142S and R179H are probably harmless. PMID:26580603

  19. Thermal Stability of Ni-Mn Electrodeposits

    SciTech Connect

    Talin, A. A.; Marquis, E. A.; Goods, S. H.; Kelly, J. J.; Miller, Michael K

    2006-01-01

    The effect of Mn additions on the structural stability of electrodeposited Ni is investigated by comparing the microstructure evolution of Ni and Ni-Mn specimens with similar crystallographic initial textures. As deposited, Ni-Mn electrodeposits have a smaller crystallite size and substantially higher yield strength than Ni deposits, in agreement with the Hall-Petch relationship. Moreover, dilute Ni-Mn electrodeposits exhibit a thermal stability that significantly exceeds that of pure Ni. Indeed, Ni-Mn retains its texture, fine-grain microstructure, and strength above 500 C (for 1 h anneal), and does not recrystallize up to 800 C. In contrast, pure Ni with larger average grain size and similar preferred orientation shows abnormal grain growth at 300 C and recrystallization at 600 C. This study suggests two distinct temperature regimes. Below 600 C, grain boundary segregation appears as a plausible mechanism for the thermal stability of Ni-Mn electrodeposits, whereas grain boundary pinning by precipitation contributes to the improved microstructural stability of Ni-Mn above 600 C.

  20. Testing for Plausibly Causal Links Between Parental Bereavement and Child Socio-Emotional and Academic Outcomes: A Propensity-Score Matching Model.

    PubMed

    Williams, Leslie D; Lawrence Aber, J

    2016-05-01

    The extant literature on parentally bereaved children has focused almost exclusively on the presence of negative mental health and socio-emotional outcomes among these children. However, findings from this literature have been equivocal. While some authors have found support for the presence of higher levels of internalizing and externalizing problems or mental health problems among this population, others have not found such a relationship. Additionally, study designs in this body of literature have limited both the internal and external validity of the research on parentally bereaved children. The present study seeks to address these issues of internal and external validity by utilizing propensity-score matching analyses to make plausibly causal inferences about the relationship between bereavement and internalizing and externalizing problems among children from a nearly nationally representative sample. This study also extends examination of the influence of parental bereavement to other domains of child development: namely, to academic outcomes. Findings suggest a lack of support for causal relationships between parental bereavement and either socio-emotional or academic outcomes among U.S. children. The plausibility of assumptions necessary to draw causal inferences is discussed. PMID:26340883

  1. Analysis of multi-domain hypothetical proteins containing iron-sulphur clusters and fad ligands reveal rieske dioxygenase activity suggesting their plausible roles in bioremediation

    PubMed Central

    Sathyanarayanan, Nitish; Nagendra, Holenarasipur Gundurao

    2012-01-01

    ‘Conserved hypothetical’ proteins pose a challenge not just for functional genomics, but also to biology in general. As long as there are hundreds of conserved proteins with unknown function in model organisms such as Escherichia coli, Bacillus subtilis or Saccharomyces cerevisiae, any discussion towards a ‘complete’ understanding of these biological systems will remain a wishful thinking. Insilico approaches exhibit great promise towards attempts that enable appreciating the plausible roles of these hypothetical proteins. Among the majority of genomic proteins, two-thirds in unicellular organisms and more than 80% in metazoa, are multi-domain proteins, created as a result of gene duplication events. Aromatic ring-hydroxylating dioxygenases, also called Rieske dioxygenases (RDOs), are class of multi-domain proteins that catalyze the initial step in microbial aerobic degradation of many aromatic compounds. Investigations here address the computational characterization of hypothetical proteins containing Ferredoxin and Flavodoxin signatures. Consensus sequence of each class of oxidoreductase was obtained by a phylogenetic analysis, involving clustering methods based on evolutionary relationship. A synthetic sequence was developed by combining the consensus, which was used as the basis to search for their homologs via BLAST. The exercise yielded 129 multidomain hypothetical proteins containing both 2Fe-2S (Ferredoxin) and FNR (Flavodoxin) domains. In the current study, 40 proteins with N-terminus 2Fe-2S domain and C-terminus FNR domain are characterized, through homology modelling and docking exercises which suggest dioxygenase activity indicating their plausible roles in degradation of aromatic moieties. PMID:23275712

  2. Complex derivatives

    NASA Astrophysics Data System (ADS)

    Battiston, Stefano; Caldarelli, Guido; Georg, Co-Pierre; May, Robert; Stiglitz, Joseph

    2013-03-01

    The intrinsic complexity of the financial derivatives market has emerged as both an incentive to engage in it, and a key source of its inherent instability. Regulators now faced with the challenge of taming this beast may find inspiration in the budding science of complex systems.

  3. Phase stabilization of spatiotemporally multiplexed ultrafast amplifiers.

    PubMed

    Mueller, M; Kienel, M; Klenke, A; Eidam, T; Limpert, J; Tünnermann, A

    2016-04-18

    Actively stabilized, simultaneous spatial and temporal coherent beam combination is a promising power-scaling technique for ultrafast laser systems. For a temporal combination based on optical delay lines, multiple stable states of operation arise for common stabilization techniques. A time resolved Jones' calculus is applied to investigate the issue. A mitigation strategy based on a temporally gated error signal acquisition is derived and demonstrated, enabling to stabilize laser systems with arbitrary numbers of amplifier channels and optical delay lines. PMID:27137231

  4. Stability of missile forces and defenses

    SciTech Connect

    Canavan, G.H.

    1997-04-01

    This note derives the exchange equation for mixes of missiles and defenses and discusses the impact on stability of varying their relative proportions. For fixed offenses increasing defenses decreases stability until first strikes fall to zero. The same is true of decreasing offenses for fixed defenses, although the decrease in indices is smaller. A judicious increase in defenses and decrease in offenses should effect that transition with minimum loss of stability.

  5. On the marginal stability of upwind schemes

    NASA Astrophysics Data System (ADS)

    Gressier, J.; Moschetta, J.-M.

    Following Quirk's analysis of Roe's scheme, general criteria are derived to predict the odd-even decoupling. This analysis is applied to Roe's scheme, EFM Pullin's scheme, EIM Macrossan's scheme and AUSM Liou's scheme. Strict stability is shown to be desirable to avoid most of these flaws. Finally, the link between marginal stability and accuracy on shear waves is established.

  6. Androctonin, a hydrophilic disulphide-bridged non-haemolytic anti-microbial peptide: a plausible mode of action.

    PubMed Central

    Hetru, C; Letellier, L; Oren, Z; Hoffmann, J A; Shai, Y

    2000-01-01

    Androctonin is a 25-residue non-haemolytic anti-microbial peptide isolated from the scorpion Androctonus australis and contains two disulphide bridges. Androctonin is different from known native anti-microbial peptides, being a relatively hydrophilic and non-amphipathic molecule. This raises the possibility that the target of androctonin might not be the bacterial membrane, shown to be a target for most amphipathic lytic peptides. To shed light on its mode of action on bacteria and its non-haemolytic activity, we synthesized androctonin, its fluorescent derivatives and its all-D-amino acid enantiomer. The enantiomer preserved high activity, suggesting a lipid-peptide interaction between androctonin and bacterial membranes. In Gram-positive and (at higher concentrations) Gram-negative bacteria, androctonin induced an immediate perturbation of the permeability properties of the cytoplasmic membrane of the bacterial energetic state, concomitant with perturbation of the morphology of the cell envelope as revealed by electron microscopy. Androctonin binds only to negatively charged lipid vesicles and induces the leakage of markers at high concentrations and with a slow kinetics, in contrast with amphipathic alpha-helical anti-microbial peptides that bind and permeate negatively charged vesicles, and to a smaller extent also zwitterionic ones. This might explain the selective lytic activity of androctonin towards bacteria but not red blood cells. Polarized attenuated total reflection-Fourier transform infrared spectroscopy revealed that androctonin adopts a beta-sheet structure in membranes and did not affect the lipid acyl chain order, which supports a detergent-like effect. The small size of androctonin, its hydrophilic character and its physicochemical properties are favourable features for its potential application as a replacement for commercially available antibiotics to which bacteria have developed resistance. PMID:10642525

  7. Pyrethrum stabilization by inactivation of natural acetylenic impurities

    SciTech Connect

    Evans, A.J.

    1989-01-17

    This patent describes a mixture of naturally occurring pyrethroid substances and derivatives of naturally occurring polyacetylenic substances wherein the derivatives of polyacetylenic substances are formed by substantially inactivating the acetylenic functional groups to promote the stability of the pyrethroid substances.

  8. Vibrational stability of graphene

    NASA Astrophysics Data System (ADS)

    Hu, Yangfan; Wang, Biao

    2013-05-01

    The mechanical stability of graphene as temperature rises is analyzed based on three different self-consistent phonon (SCP) models. Compared with three-dimensional (3-D) materials, the critical temperature Ti at which instability occurs for graphene is much closer to its melting temperature Tm obtained from Monte Carlo simulation (Ti ≃ 2Tm, K. V. Zakharchenko, A. Fasolino, J. H. Los, and M. I. Katsnelson, J. Phys. Condens. Matter 23, 202202). This suggests that thermal vibration plays a significant role in melting of graphene while melting for 3-D materials is often dominated by topologic defects. This peculiar property of graphene derives from its high structural anisotropy, which is characterized by the vibrational anisotropic coefficient (VAC), defined upon its Lindermann ratios in different directions. For any carbon based material with a graphene-like structure, the VAC value must be smaller than 5.4 to maintain its stability. It is also found that the high VAC value of graphene is responsible for its negative thermal expansion coefficient at low temperature range. We believe that the VAC can be regarded as a new criterion concerning the vibrational stability of any low-dimensional (low-D) materials.

  9. Stabilizing brokerage

    PubMed Central

    Stovel, Katherine; Golub, Benjamin; Milgrom, Eva M. Meyersson

    2011-01-01

    A variety of social and economic arrangements exist to facilitate the exchange of goods, services, and information over gaps in social structure. Each of these arrangements bears some relationship to the idea of brokerage, but this brokerage is rarely like the pure and formal economic intermediation seen in some modern markets. Indeed, for reasons illuminated by existing sociological and economic models, brokerage is a fragile relationship. In this paper, we review the causes of instability in brokerage and identify three social mechanisms that can stabilize fragile brokerage relationships: social isolation, broker capture, and organizational grafting. Each of these mechanisms rests on the emergence or existence of supporting institutions. We suggest that organizational grafting may be the most stable and effective resolution to the tensions inherent in brokerage, but it is also the most institutionally demanding. PMID:22198763

  10. STABILIZED OSCILLATOR

    DOEpatents

    Jessen, P.L.; Price, H.J.

    1958-03-18

    This patent relates to sine-wave generators and in particular describes a generator with a novel feedback circuit resulting in improved frequency stability. The generator comprises two triodes having a common cathode circuit connected to oscillate at a frequency and amplitude at which the loop galn of the circutt ls unity, and another pair of triodes having a common cathode circuit arranged as a conventional amplifier. A signal is conducted from the osciliator through a frequency selective network to the amplifier and fed back to the osciliator. The unique feature of the feedback circuit is the amplifier operates in the nonlinear portion of its tube characteristics thereby providing a relatively constant feedback voltage to the oscillator irrespective of the amplitude of its input signal.

  11. Anticipating and Communicating Plausible Environmental and Health Concerns Associated with Future Disasters: The ShakeOut and ARkStorm Scenarios as Examples

    NASA Astrophysics Data System (ADS)

    Plumlee, G. S.; Morman, S. A.; Alpers, C. N.; Hoefen, T. M.; Meeker, G. P.

    2010-12-01

    Disasters commonly pose immediate threats to human safety, but can also produce hazardous materials (HM) that pose short- and long-term environmental-health threats. The U.S. Geological Survey (USGS) has helped assess potential environmental health characteristics of HM produced by various natural and anthropogenic disasters, such as the 2001 World Trade Center collapse, 2005 hurricanes Katrina and Rita, 2007-2009 southern California wildfires, various volcanic eruptions, and others. Building upon experience gained from these responses, we are now developing methods to anticipate plausible environmental and health implications of the 2008 Great Southern California ShakeOut scenario (which modeled the impacts of a 7.8 magnitude earthquake on the southern San Andreas fault, http://urbanearth.gps.caltech.edu/scenario08/), and the recent ARkStorm scenario (modeling the impacts of a major, weeks-long winter storm hitting nearly all of California, http://urbanearth.gps.caltech.edu/winter-storm/). Environmental-health impacts of various past earthquakes and extreme storms are first used to identify plausible impacts that could be associated with the disaster scenarios. Substantial insights can then be gleaned using a Geographic Information Systems (GIS) approach to link ShakeOut and ARkStorm effects maps with data extracted from diverse database sources containing geologic, hazards, and environmental information. This type of analysis helps constrain where potential geogenic (natural) and anthropogenic sources of HM (and their likely types of contaminants or pathogens) fall within areas of predicted ShakeOut-related shaking, firestorms, and landslides, and predicted ARkStorm-related precipitation, flooding, and winds. Because of uncertainties in the event models and many uncertainties in the databases used (e.g., incorrect location information, lack of detailed information on specific facilities, etc.) this approach should only be considered as the first of multiple steps

  12. A parametric study of planform and aeroelastic effects on aerodynamic center, alpha- and q- stability derivatives. Appendix C: Method for computing the aerodynamic influence coefficient matrix of nonplanar wing-body-tail configurations

    NASA Technical Reports Server (NTRS)

    Roskam, J.

    1972-01-01

    Expressions are derived for computing the aerodynamic influence coefficient matrix for nonplanar wing-body-tail configurations. An aerodynamic influence coefficient is defined as the load in lbs. induced on a panel as a result of a unit angle of attack on another panel. Fuselage, wing and tail thickness are assumed to be small with the result that the thickness effect on the flow-field is negligible. The method for determining the aerodynamic influence coefficient matrix is based on the lifting solution to the small perturbation, steady potential flow equation.

  13. Non-Linear Spring Equations and Stability

    ERIC Educational Resources Information Center

    Fay, Temple H.; Joubert, Stephan V.

    2009-01-01

    We discuss the boundary in the Poincare phase plane for boundedness of solutions to spring model equations of the form [second derivative of]x + x + epsilonx[superscript 2] = Fcoswt and the [second derivative of]x + x + epsilonx[superscript 3] = Fcoswt and report the results of a systematic numerical investigation on the global stability of…

  14. An Italian population-based case-control study on the association between farming and cancer: Are pesticides a plausible risk factor?

    PubMed

    Salerno, Christian; Carcagnì, Antonella; Sacco, Sara; Palin, Lucio Antonio; Vanhaecht, Kris; Panella, Massimiliano; Guido, Davide

    2016-05-01

    This population-based case-control study investigated the association between farming (a proxy for pesticide exposure) and cancer in the Vercelli suburban area (northwest Italy). The residents, aged 25 to 79 years, in the above-mentioned area during the period 2002-2009 were considered. Cases were all the first hospital admissions for cancer. Controls were all the subjects not included in the cases and not excluded from the study. Cases and controls were classified according to whether they occupationally resulted farmers or nonfarmers during the period 1965-2009. Cancer odds ratios (ORs) between farmers and nonfarmers were calculated with generalized linear mixed models adjusted by gender and age. Farmers showed higher odds for all cancers (OR=1.459; p < .001), nonmelanoma skin cancer, colorectal cancer, and breast cancer. The results suggest a plausible association between pesticide exposure and cancer occurrence. PMID:25942634

  15. Refinement of the background ionospheric conditions and plausible explanation based on neutral dynamics for the occurrence/non-occurrence of L-band scintillation patches against forecast.

    NASA Astrophysics Data System (ADS)

    Sridharan, R.; Jose, Lijo; Bagiya, Mala S.; Sunda, Surendra; Chaudhary, R. K.; Pant, Tarun K.

    2015-10-01

    The recently evolved L-band scintillation forecast mechanism based on the characteristic features of the daytime F-region electron density fluctuations and also on the basic ionospheric conditions had been successful to a reasonable extent in forecasting the spatio-temporal map of scintillation patches. There had been a few non-compliances in the expected pattern within/outside the forecast windows. The present paper attempts to address such non-compliances and offers a plausible explanation based on neutral dynamics, especially the local time variation of vertical winds over the magnetic equator, while at the same time refining the earlier stipulated background ionospheric conditions. With the above refinements, it is anticipated that the forecast mechanism would become very robust. The present results highlight the importance of the neutral dynamical parameters and the urgent need to concentrate on the efforts to make systematic measurements of the same in order to characterize their variability.

  16. Is the Framework of Cohn's 'Tritope Model' for How T Cell Receptors Recognize Peptide/Self-MHC Complexes and Allo-MHC Plausible?

    PubMed

    Bretscher, Peter A

    2016-05-01

    Cohn has developed the tritope model to describe how distinct domains of the T cell receptor (TcR) recognize peptide/self-MHC complexes and allo-MHC. He has over the years employed this model as a framework for considering how the TcR might mediate various signals [1-5]. In a recent publication [5], Cohn employs the Tritope Model to propose a detailed mechanism for the T cell receptor's involvement in positive thymic selection [5]. During a review of this proposal, I became uneasy over the plausibility of the underlying framework of the Tritope Model. I outline here the evolutionary considerations making me question this framework. I also suggest that the proposed framework underlying the Tritope Model makes strong predictions whose validity can most probably be assessed by considering observations reported in the literature. PMID:26991815

  17. Quench propagation velocity for highly stabilized conductors

    SciTech Connect

    Mints, R.G. |; Ogitsu, T. |; Devred, A.

    1995-05-01

    Quench propagation velocity in conductors having a large amount of stabilizer outside the multifilamentary area is considered. It is shown that the current redistribution process between the multifilamentary area and the stabilizer can strongly effect the quench propagation. A criterion is derived determining the conditions under which the current redistribution process becomes significant, and a model of effective stabilizer area is suggested to describe its influence on the quench propagation velocity. As an illustration, the model is applied to calculate the adiabatic quench propagation velocity for a conductor geometry with a multifilamentary area embedded inside the stabilizer.

  18. Density Functional Theory-Derived Group Additivity and Linear Scaling Methods for Prediction of Oxygenate Stability on Metal Catalysts. Adsorption of Open-Ring Alcohol and Polyol Dehydrogenation Intermediates on Pt-Based Metals

    SciTech Connect

    Salciccioli, Michael; Chen, Ying; Vlachos, Dion G.

    2010-11-09

    Semiempirical methods for prediction of thermochemical properties of adsorbed oxygenates are developed. Periodic density functional theory calculations are used to study the relative stability of ethanol, ethylene glycol, isopropyl alcohol, and glycerol dehydrogenation intermediates on Pt(111). For ethylene glycol dehydrogenation intermediates, it is found that the thermodynamically favored intermediates at each level of dehydrogenation are as follows: HOCH2CHOH, HOCHCHOH, HOCHCOH, HOCCOH ≈ HOCHCO, HOCCO, OCCO. Structural and energetic patterns emerge from these C2HxO2 adsorption calculations that lead to the formation of group additive properties for thermochemical property prediction of oxygenates on Pt(111). Finally, linear scaling relationships of atomic binding energy are used to predict the binding energy of the C2HxO2 species on the Ni(111) surface and Ni-Pt-Pt(111) bimetallic surface. It is shown that the linear scaling relationships can accurately predict the binding energy of larger oxygenates as well as of oxygenates on bimetallic catalysts. Corrections for ring strain and weak oxygen-metal and hydrogen-bonding interactions are added to increase the accuracy of group additivity and linear scaling relationships.

  19. On Ideal Stability of Cylindrical Localized Interchange Modes

    SciTech Connect

    Umansky, M V

    2007-05-15

    Stability of cylindrical localized ideal pressure-driven interchange plasma modes is revisited. Converting the underlying eigenvalue problem into the form of the Schroedinger equation gives a new simple way of deriving the Suydam stability criterion and calculating the growth rates of unstable modes. Near the marginal stability limit the growth rate is exponentially small and the mode has a double-peak structure.

  20. Composite stabilizer unit

    DOEpatents

    Ebaugh, Larry R.; Sadler, Collin P.; Carter, Gary D.

    1992-01-01

    An improved fin stabilized projectile including multiple stabilizer fins upon a stabilizer unit situated at the aft end of the projectile is provided, the improvement wherein the stabilizer fins are joined into the stabillizer unit by an injection molded engineering grade polymer.

  1. Plasma stabilization experiment

    NASA Astrophysics Data System (ADS)

    Sziklas, E. A.; Fader, W. J.; Jong, R. A.; Stufflebeam, J. H.

    1980-07-01

    The plasma stabilization experiment is an effort to enhance stability in a mirror-confined plasma by trapping cold ions with rf fields applied near the mirror throats. Nagoya Type 3 antennas, coupled to a 60 kW rf power supply are mounted in the throats of the UTRC baseball magnet. An external washer gun provides a source of plasma for both streaming and confined plasma tests. Results show a strong stoppering effect on streaming plasmas and a marginal effect on confined plasmas. Theoretical calculations provide an explanation for the experimental observations. The field generates a ponderomotive force acting on the electrons. The resultant improvement in electron confinement changes the ambipolar potential and inhibits the flow of ions through the mirror throat. Criteria are derived for the validity of this trapping concept. The requisite field strengths are significantly lower than those required to trap ions directly. Scaling laws are developed for application of cold ion trapping to large mirror devices containing dense plasmas. The use of slow-wave antenna structures operated at frequencies above the lower hybrid frequency is recommended for these applications.

  2. Stabilization of betalains: A review.

    PubMed

    Khan, Mohammad Imtiyaj

    2016-04-15

    Betalains are vacuolar pigments composed of a nitrogenous core structure, betalamic acid [4-(2-oxoethylidene)-1,2,3,4-tetrahydropyridine-2,6-dicarboxylic acid]. This compound consists of a chromophore substructure 1,7-diazaheptamethin. Betalamic acid condenses with imino compounds (cyclo-DOPA or its glucosyl derivatives), or amines and/or their derivatives to form a variety of betacyanins (violet) and betaxanthins (yellow), respectively. These pigments exhibit absorption maxima in between 532-550 nm and 457-485 nm, respectively. These colors are currently in use as food additives as they are bioactive and completely safe to consume. However, owing to poor stability, their potential application in pharmaceuticals and cosmetics is severely compromised. There is a lack of scientific reports highlighting their superior tinctorial strength including fluorescence, and their excellent water solubility. For widening the color spectrum and their usage, various betalain-rich extracts have been reviewed here, focusing on their matrix effects on stability vis-a-vis purified pigments of different structural make-up. This review also encompasses work carried out in the past related to stability/stabilization of betalains and future research direction for the same. PMID:26675869

  3. Towards a more plausible dragon

    NASA Astrophysics Data System (ADS)

    Efthimiou, Costas

    2014-08-01

    Wizards, mermaids, dragons and aliens. Walking, running, flying and space travel. A hi-tech elevator, a computer, a propulsion engine and a black hole. What do all of these things have in common? This might seem like a really hard brainteaser but the answer is simple: they all obey the fundamental laws of our universe.

  4. Plausible Mechanisms of Cadmium Carcinogenesis

    EPA Science Inventory

    Cadmium is a transition metal and an ubiquitous environmental and industrial pollutant. Laboratory animal studies and epidemiological studies have shown that exposure to cadmium is associated with various organ toxicities and carcinogenic effects. Several national and internation...

  5. Plausible surface models for Titan

    NASA Technical Reports Server (NTRS)

    Lunine, Jonathan I.

    1992-01-01

    Current understanding of the nature of Titan's surface and some new ideas for explaining the curious radar returns from Saturn's largest satellite are reviewed. Pre-Voyager models of the surface, based largely on cosmochemistry and the discovery of atmospheric methane, allowed for a range of possibilities, including pure methane oceans. The Voyager 1 flyby ruled out this last possibility, replacing it with compelling observational arguments in favor of a mixed light hydrocarbon and nitrogen ocean. Ground based radar observations indicated a surprisingly reflective surface which is inconsistent with a hydrocarbon ocean and more reminiscent of the Galilean Satellites. Nonetheless, passive radiometric measurements of the surface do not support the notion that Titan's surface is like that of the Galilean satellites. One of the arguments against hydrocarbon oceans reflecting radar energy is that most solid, complex hydrocarbon and nitriles will be denser than the liquid and sink. Nonetheless, many of the aerosol species will coagulate in highly nonspherical patterns, and some species probably polymerize in long chains. Such chains will have very low sedimendation velocities in the ocean and may remain near the surface through ocean mixing process. The prospect of an oceanic 'soup' of polar polymers acting as volume reflectors at radio wevelengths suggests that the interpretation of radar observations needs evaluation.

  6. Stability constraints on large-scale structural brain networks

    PubMed Central

    Gray, Richard T.; Robinson, Peter A.

    2013-01-01

    Stability is an important dynamical property of complex systems and underpins a broad range of coherent self-organized behavior. Based on evidence that some neurological disorders correspond to linear instabilities, we hypothesize that stability constrains the brain's electrical activity and influences its structure and physiology. Using a physiologically-based model of brain electrical activity, we investigated the stability and dispersion solutions of networks of neuronal populations with propagation time delays and dendritic time constants. We find that stability is determined by the spectrum of the network's matrix of connection strengths and is independent of the temporal damping rate of axonal propagation with stability restricting the spectrum to a region in the complex plane. Time delays and dendritic time constants modify the shape of this region but it always contains the unit disk. Instabilities resulting from changes in connection strength initially have frequencies less than a critical frequency. For physiologically plausible parameter values based on the corticothalamic system, this critical frequency is approximately 10 Hz. For excitatory networks and networks with randomly distributed excitatory and inhibitory connections, time delays and non-zero dendritic time constants have no impact on network stability but do effect dispersion frequencies. Random networks with both excitatory and inhibitory connections can have multiple marginally stable modes at low delta frequencies. PMID:23630490

  7. Stability of climate reconstructions

    NASA Astrophysics Data System (ADS)

    Lohmann, Gerrit; Rimbu, Norel; Wagner, Axel; Dima, Mihai

    2014-05-01

    Reconstruction of climate mode indices using proxy data as predictors is limited due to non-stationarity in atmospheric teleconnections. In this paper a method is presented to identify stable predictors for the reconstruction of the Arctic Oscillation (AO) index. Using the 20th Century reanalysis data, the AO index is calculated for the last 140 years and correlated with global two meter temperature, precipitation, and sea surface temperature anomalies in various moving windows. The stability of the correlation was checked in every point of the global grids. Anomalies from the regions where the correlation of the AO index is stable are used as stable predictors for the AO index. It is shown that the predictors identified through our analysis lead to proper AO reconstructions. Statistical analysis of a global climate simulation covering the last millennium reveals that the stability correlation map of model AO and temperature are very similar to the corresponding observed correlation stability map. It is shown that the stability correlation maps of the AO, as derived from the model, are insensitive to different climate forcing and can be used to systematically select stable predictors for the AO reconstruction during the last millennium and most likely for the late Holocene. Finally, several high resolution proxy data from the stable regions are selected and used for a reconstruction of the AO index during the last three centuries. We argue that selection of proxy data from the stable regions of AO teleconnections leads to a suitable AO reconstruction. Furthermore, the hypothesis of stable teleconnections is tested using atmospheric circulation model experiments. For climate conditions with other ice sheet distributions on the Northern Hemisphere, such as the last glacial maximum climate, considerable changes are detected in the atmospheric variability pattern compared to the present day. Correlation maps of pseudo proxy records over Europe, the Red Sea area, and

  8. Stability and control of maneuvering high-performance aircraft

    NASA Technical Reports Server (NTRS)

    Stengel, R. F.; Berry, P. W.

    1977-01-01

    The stability and control of a high-performance aircraft was analyzed, and a design methodology for a departure prevention stability augmentation system (DPSAS) was developed. A general linear aircraft model was derived which includes maneuvering flight effects and trim calculation procedures for investigating highly dynamic trajectories. The stability and control analysis systematically explored the effects of flight condition and angular motion, as well as the stability of typical air combat trajectories. The effects of configuration variation also were examined.

  9. Untemplated nonenzymatic polymerization of 3',5'cGMP: a plausible route to 3',5'-linked oligonucleotides in primordia.

    PubMed

    Šponer, Judit E; Šponer, Jiří; Giorgi, Alessandra; Di Mauro, Ernesto; Pino, Samanta; Costanzo, Giovanna

    2015-02-19

    The high-energy 3',5' phosphodiester linkages conserved in 3',5' cyclic GMPs offer a genuine solution for monomer activation required by the transphosphorylation reactions that could lead to the emergence of the first simple oligonucleotide sequences on the early Earth. In this work we provide an in-depth characterization of the effect of the reaction conditions on the yield of the polymerization reaction of 3',5' cyclic GMPs both in aqueous environment as well as under dehydrating conditions. We show that the threshold temperature of the polymerization is about 30 °C lower under dehydrating conditions than in solution. In addition, we present a plausible exergonic reaction pathway for the polymerization reaction, which involves transient formation of anionic centers at the O3' positions of the participating riboses. We suggest that excess Na(+) cations inhibit the polymerization reaction because they block the anionic mechanism via neutralizing the negatively charged O3'. Our experimental findings are compatible with a prebiotic scenario, where gradual desiccation of the environment could induce polymerization of 3',5' cyclic GMPs synthesized in liquid. PMID:25625780

  10. Wedelolactone mitigates UVB induced oxidative stress, inflammation and early tumor promotion events in murine skin: plausible role of NFkB pathway.

    PubMed

    Ali, Farrah; Khan, Bilal Azhar; Sultana, Sarwat

    2016-09-01

    UVB (Ultra-violet B) radiation is one of the major etiological factors in various dermal pathology viz. dermatitis, actinic folliculitis, solar urticaria, psoriasis and cancer among many others. UVB causes toxic manifestation in tissues by inciting inflammatory and tumor promoting events. We have designed this study to assess the anti-inflammatory and anti-tumor promotion effect of Wedelolactone (WDL) a specific IKK inhibitor. Results indicate significant restoration of anti-oxidative enzymes due to WDL treatments. We also found that WDL was effective in mitigating inflammatory markers consisting of MPO (myeloperoxidase), Mast cells trafficking, Langerhans cells suppression and COX 2 expression up regulation due to UVB exposure. We also deduce that WDL presented a promising intervention in attenuating early tumor promotion events caused by UVB exposure as indicated by the results of ODC (Ornithine Decarboxylase), Thymidine assay, Vimentin and VEGF (Vascular-endothelial growth factor) expression. This study was able to provide substantial cues for the therapeutic ability of Wedelolactone against inflammatory and tumor promoting events in murine skin depicting plausible role of NFkB pathway. PMID:27164422

  11. Observational evidence for the plausible linkage of Equatorial Electrojet (EEJ) electric field variations with the post sunset F-region electrodynamics

    NASA Astrophysics Data System (ADS)

    Sreeja, V.; Devasia, C. V.; Ravindran, Sudha; Pant, Tarun Kumar

    2009-11-01

    The paper is based on a detailed observational study of the Equatorial Spread F (ESF) events on geomagnetically quiet (Ap≤20) days of the solar maximum (2001), moderate (2004) and minimum (2006) years using the ionograms and magnetograms from the magnetic equatorial location of Trivandrum (8.5° N; 77° E; dip lat ~0.5° N) in India. The study brings out some interesting aspects of the daytime Equatorial Electrojet (EEJ) related electric field variations and the post sunset F-region electrodynamics governing the nature of seasonal characteristics of the ESF phenomena during these years. The observed results seem to indicate a plausible linkage of daytime EEJ related electric field variations with pre-reversal enhancement which in turn is related to the occurrence of ESF. These electric field variations are shown to be better represented through a parameter, termed as "E", in the context of possible coupling between the E- and F-regions of the ionosphere. The observed similarities in the gross features of the variations in the parameter "E" and the F-region vertical drift (Vz) point towards the potential usage of the EEJ related parameter "E" as an useful index for the assessment of Vz prior to the occurrence of ESF.

  12. Trapped particle stability for the kinetic stabilizer

    NASA Astrophysics Data System (ADS)

    Berk, H. L.; Pratt, J.

    2011-08-01

    A kinetically stabilized axially symmetric tandem mirror (KSTM) uses the momentum flux of low-energy, unconfined particles that sample only the outer end-regions of the mirror plugs, where large favourable field-line curvature exists. The window of operation is determined for achieving magnetohydrodynamic (MHD) stability with tolerable energy drain from the kinetic stabilizer. Then MHD stable systems are analysed for stability of the trapped particle mode. This mode is characterized by the detachment of the central-cell plasma from the kinetic-stabilizer region without inducing field-line bending. Stability of the trapped particle mode is sensitive to the electron connection between the stabilizer and the end plug. It is found that the stability condition for the trapped particle mode is more constraining than the stability condition for the MHD mode, and it is challenging to satisfy the required power constraint. Furthermore, a severe power drain may arise from the necessary connection of low-energy electrons in the kinetic stabilizer to the central region.

  13. Plutonium inventories for stabilization and stabilized materials

    SciTech Connect

    Williams, A.K.

    1996-05-01

    The objective of the breakout session was to identify characteristics of materials containing plutonium, the need to stabilize these materials for storage, and plans to accomplish the stabilization activities. All current stabilization activities are driven by the Defense Nuclear Facilities Safety Board Recommendation 94-1 (May 26, 1994) and by the recently completed Plutonium ES&H Vulnerability Assessment (DOE-EH-0415). The Implementation Plan for accomplishing stabilization of plutonium-bearing residues in response to the Recommendation and the Assessment was published by DOE on February 28, 1995. This Implementation Plan (IP) commits to stabilizing problem materials within 3 years, and stabilizing all other materials within 8 years. The IP identifies approximately 20 metric tons of plutonium requiring stabilization and/or repackaging. A further breakdown shows this material to consist of 8.5 metric tons of plutonium metal and alloys, 5.5 metric tons of plutonium as oxide, and 6 metric tons of plutonium as residues. Stabilization of the metal and oxide categories containing greater than 50 weight percent plutonium is covered by DOE Standard {open_quotes}Criteria for Safe Storage of Plutonium Metals and Oxides{close_quotes} December, 1994 (DOE-STD-3013-94). This standard establishes criteria for safe storage of stabilized plutonium metals and oxides for up to 50 years. Each of the DOE sites and contractors with large plutonium inventories has either started or is preparing to start stabilization activities to meet these criteria.

  14. Parameter margins for stabilized conservative multilinear systems

    NASA Technical Reports Server (NTRS)

    Warren, Wayne; Wie, Bong

    1991-01-01

    Simple and elegant derivations of recent results concerning the computation of infinity-norm real-parameter margins for stabilized, mass-spring dynamical systems with the masses and the spring constraints as uncertain parameters are presented. The authors introduce the concept of critical frequency and gain for stabilized conservative systems whose uncertain parameters do not necessarily appear multilinearly in the numerator and denominator of the plant transfer function. An approach to parameter margin computation is presented.

  15. Volvalerine A, an unprecedented N-containing sesquiterpenoid dimer derivative from Valeriana officinalis var. latifolia.

    PubMed

    Wang, Peng-Cheng; Ran, Xin-Hui; Luo, Huai-Rong; Ma, Qing-Yun; Zhou, Jun; Hu, Jiang-Miao; Zhao, You-Xing

    2016-03-01

    Volvalerine A (1), a novel N-containing bisesquiterpenoid derivative with a dihydroisoxazole ring, and its possible biosynthetic precursor, 1-hydroxy-1,11,11-trimethyldecahydrocyclopropane azulene-10-one (2), were isolated from the roots of Valeriana officinalis var. latifolia. Their structures and relative configurations were identified using spectroscopic data and X-ray crystallography. A plausible biosynthetic pathway for 1 is also presented. PMID:26779941

  16. Parabolized stability equations

    NASA Astrophysics Data System (ADS)

    Herbert, Thorwald

    1994-04-01

    The parabolized stability equations (PSE) are a new approach to analyze the streamwise evolution of single or interacting Fourier modes in weakly nonparallel flows such as boundary layers. The concept rests on the decomposition of every mode into a slowly varying amplitude function and a wave function with slowly varying wave number. The neglect of the small second derivatives of the slowly varying functions with respect to the streamwise variable leads to an initial boundary-value problem that can be solved by numerical marching procedures. The PSE approach is valid in convectively unstable flows. The equations for a single mode are closely related to those of the traditional eigenvalue problems for linear stability analysis. However, the PSE approach does not exploit the homogeneity of the problem and, therefore, can be utilized to analyze forced modes and the nonlinear growth and interaction of an initial disturbance field. In contrast to the traditional patching of local solutions, the PSE provide the spatial evolution of modes with proper account for their history. The PSE approach allows studies of secondary instabilities without the constraints of the Floquet analysis and reproduces the established experimental, theoretical, and computational benchmark results on transition up to the breakdown stage. The method matches or exceeds the demonstrated capabilities of current spatial Navier-Stokes solvers at a small fraction of their computational cost. Recent applications include studies on localized or distributed receptivity and prediction of transition in model environments for realistic engineering problems. This report describes the basis, intricacies, and some applications of the PSE methodology.

  17. Stability of a liquid bridge under vibration.

    PubMed

    Benilov, E S

    2016-06-01

    We examine the stability of a vertical liquid bridge between two vertically vibrating, coaxial disks. Assuming that the vibration amplitude and period are much smaller than the mean distance between the disks and the global timescale, respectively, we employ the method of multiple scales to derive a set of asymptotic equations. The set is then used to examine the stability of a bridge of an almost cylindrical shape. It is shown that, if acting alone, gravity is a destabilizing influence, whereas vibration can weaken it or even eliminate altogether. Thus, counter-intuitively, vibration can stabilize an otherwise unstable capillary structure. PMID:27415369

  18. Thermodynamical stability of the Bardeen black hole

    SciTech Connect

    Bretón, Nora; Perez Bergliaffa, Santiago E.

    2014-01-14

    We analyze the stability of the regular magnetic Bardeen black hole both thermodynamically and dynamically. For the thermodynamical analysis we consider a microcanonical ensemble and apply the turning point method. This method allows to decide a change in stability (or instability) of a system, requiring only the assumption of smoothness of the area functional. The dynamical stability is asserted using criteria based on the signs of the Lagrangian and its derivatives. It turns out from our analysis that the Bardeen black hole is both thermodynamically and dynamically stable.

  19. Stability of a liquid bridge under vibration

    NASA Astrophysics Data System (ADS)

    Benilov, E. S.

    2016-06-01

    We examine the stability of a vertical liquid bridge between two vertically vibrating, coaxial disks. Assuming that the vibration amplitude and period are much smaller than the mean distance between the disks and the global timescale, respectively, we employ the method of multiple scales to derive a set of asymptotic equations. The set is then used to examine the stability of a bridge of an almost cylindrical shape. It is shown that, if acting alone, gravity is a destabilizing influence, whereas vibration can weaken it or even eliminate altogether. Thus, counter-intuitively, vibration can stabilize an otherwise unstable capillary structure.

  20. Finite time stabilization of delayed neural networks.

    PubMed

    Wang, Leimin; Shen, Yi; Ding, Zhixia

    2015-10-01

    In this paper, the problem of finite time stabilization for a class of delayed neural networks (DNNs) is investigated. The general conditions on the feedback control law are provided to ensure the finite time stabilization of DNNs. Then some specific conditions are derived by designing two different controllers which include the delay-dependent and delay-independent ones. In addition, the upper bound of the settling time for stabilization is estimated. Under fixed control strength, discussions of the extremum of settling time functional are made and a switched controller is designed to optimize the settling time. Finally, numerical simulations are carried out to demonstrate the effectiveness of the obtained results. PMID:26264170

  1. In situ bioremediation of naphthenic acids contaminated tailing pond waters in the athabasca oil sands region--demonstrated field studies and plausible options: a review.

    PubMed

    Quagraine, E K; Peterson, H G; Headley, J V

    2005-01-01

    Currently, there are three industrial plants that recover oil from the lower Athabasca oil sands area, and there are plans in the future for several additional mines. The extraction procedures produce large volumes of slurry wastes contaminated with naphthenic acids (NAs). Because of a "zero discharge" policy the oil sands companies do not release any extraction wastes from their leases. The process-affected waters and fluid tailings contaminated with NAs are contained on-site primarily in large settling ponds. These fluid wastes from the tailing ponds can be acutely and chronically toxic to aquatic organisms, and NAs have been associated with this toxicity. The huge tailings containment area must ultimately be reclaimed, and this is of major concern to the oil sands industry. Some reclamation options have been investigated by both pioneering industries (Syncrude Energy Inc. and Suncor Inc.) with mixed results. The bioremediation techniques have limited success to date in biodegrading NAs to levels below 19 mg/L. Some tailing pond waters have been stored for more than 10 years, and it appears that the remaining high molecular weight NAs are refractory to the natural biodegradation process in the ponds. Some plausible options to further degrade the NAs in the tailings pond water include: bioaugmentation with bacteria selected to degrade the more refractory classes of NAs; the use of attachment materials such as clays to concentrate both the NA and the NA-degrading bacteria in their surfaces and/or pores; synergistic association between algae and bacteria consortia to promote efficient aerobic degradation; and biostimulation with nutrients to promote the growth and activity of the microorganisms. PMID:15756978

  2. From provocative narrative scenarios to quantitative biophysical model results: Simulating plausible futures to 2070 in an urbanizing agricultural watershed in Wisconsin, USA

    NASA Astrophysics Data System (ADS)

    Booth, E.; Chen, X.; Motew, M.; Qiu, J.; Zipper, S. C.; Carpenter, S. R.; Kucharik, C. J.; Steven, L. I.

    2015-12-01

    Scenario analysis is a powerful tool for envisioning future social-ecological change and its consequences on human well-being. Scenarios that integrate qualitative storylines and quantitative biophysical models can create a vivid picture of these potential futures but the integration process is not straightforward. We present - using the Yahara Watershed in southern Wisconsin (USA) as a case study - a method for developing quantitative inputs (climate, land use/cover, and land management) to drive a biophysical modeling suite based on four provocative and contrasting narrative scenarios that describe plausible futures of the watershed to 2070. The modeling suite consists of an agroecosystem model (AgroIBIS-VSF), hydrologic routing model (THMB), and empirical lake water quality model and estimates several biophysical indicators to evaluate the watershed system under each scenario. These indicators include water supply, lake flooding, agricultural production, and lake water quality. Climate (daily precipitation and air temperature) for each scenario was determined using statistics from 210 different downscaled future climate projections for two 20-year time periods (2046-2065 and 2081-2100) and modified using a stochastic weather generator to allow flexibility for matching specific climate events within the scenario narratives. Land use/cover for each scenario was determined first by quantifying changes in areal extent every decade for 15 categories at the watershed scale to be consistent with the storyline events and theme. Next, these changes were spatially distributed using a rule-based framework based on land suitability metrics that determine transition probabilities. Finally, agricultural inputs including manure and fertilizer application rates were determined for each scenario based on the prevalence of livestock, water quality regulations, and technological innovations. Each scenario is compared using model inputs (maps and time-series of land use/cover and

  3. Workshop on Feedback Stabilization of MHD Stabilities

    SciTech Connect

    McGuire, K.; Kugel, H.; La Haye, R.; Mauel, M.; Nevins, W.; Prager, S.

    1996-12-31

    The feedback stabilization of MHD instabilities is an area of research that is critical for improving the performance and economic attractiveness of magnetic confinement devices. A Workshop dedicated to feedback stabilization of MHD instabilities was held from December 11-13, 1996 at the Princeton Plasma Physics Laboratory, Princeton NJ, USA. The resulting presentations, conclusions, and recommendations are summarized.

  4. Constrained H-Phe-Phe-NH2 analogues with high affinity to the substance P 1-7 binding site and with improved metabolic stability and cell permeability.

    PubMed

    Fransson, Rebecca; Sköld, Christian; Kratz, Jadel M; Svensson, Richard; Artursson, Per; Nyberg, Fred; Hallberg, Mathias; Sandström, Anja

    2013-06-27

    We recently reported the discovery of H-Phe-Phe-NH2 as a small and high affinity ligand for the substance P 1-7 (SP(1-7), H-Arg-Pro-Lys-Pro-Gln-Gln-Phe-OH) specific binding site and its intriguing ability to reduce neuropathic pain. With the overall aim to develop stable and orally bioavailable SP(1-7) mimetics, the dipeptide was chosen as a lead compound. Herein the structure-activity relationship (SAR) of a set of modified H-Phe-Phe-NH2 analogues is presented together with their potential active uptake by PEPT1 transporter, intestinal permeability, and metabolic stability. Local constraints via peptide backbone methylation or preparation of cyclized analogues based on pyrrolidine were evaluated and were shown to significantly improve the in vitro pharmacokinetic properties. The SAR was rationalized by deriving a plausible binding pose for the high affinity ligands. Rigidification using a 3-phenylpyrrolidine moiety in the C-terminal of H-Phe-Phe-NH2 resulted in high affinity and improved intrinsic clearance and intestinal epithelial permeability. PMID:23735006

  5. Biological plausibility as a tool to associate analytical data for micropollutants and effect potentials in wastewater, surface water, and sediments with effects in fishes.

    PubMed

    Maier, Diana; Blaha, Ludek; Giesy, John P; Henneberg, Anja; Köhler, Heinz-R; Kuch, Bertram; Osterauer, Raphaela; Peschke, Katharina; Richter, Doreen; Scheurer, Marco; Triebskorn, Rita

    2015-04-01

    of micronuclei in erythrocytes of chub from the river. Chemicals potentially responsible for effects on DNA were identified. Embryotoxic effects on zebrafish (Danio rerio), investigated in the laboratory, were associated with embryotoxic effects in trout exposed in streamwater bypass systems at the two rivers. In general, responses at all levels of organization were more pronounced in samples from the Schussen than in those from the Argen. These results are consistent with the magnitudes of chemical pollution in these two streams. Plausibility chains to establish causality between exposures and effects and to predict effects in biota in the river from studies in the laboratory are discussed. PMID:25260601

  6. Effects of sex-sorting and sperm dosage on conception rates of Holstein heifers: is comparable fertility of sex-sorted and conventional semen plausible?

    PubMed

    Dejarnette, J M; Leach, M A; Nebel, R L; Marshall, C E; McCleary, C R; Moreno, J F

    2011-07-01

    plausibility of comparable conception rates to conventional semen in the absence of major technological advances in efficiency of sperm sorting or cryopreservation. PMID:21700034

  7. Determination of nitric oxide metabolites, nitrate and nitrite, in Anopheles culicifacies mosquito midgut and haemolymph by anion exchange high-performance liquid chromatography: plausible mechanism of refractoriness

    PubMed Central

    Sharma, Arun; Raghavendra, Kamaraju; Adak, Tridibesh; Dash, Aditya P

    2008-01-01

    Background The diverse physiological and pathological role of nitric oxide in innate immune defenses against many intra and extracellular pathogens, have led to the development of various methods for determining nitric oxide (NO) synthesis. NO metabolites, nitrite (NO2-) and nitrate (NO3-) are produced by the action of an inducible Anopheles culicifacies NO synthase (AcNOS) in mosquito mid-guts and may be central to anti-parasitic arsenal of these mosquitoes. Method While exploring a plausible mechanism of refractoriness based on nitric oxide synthase physiology among the sibling species of An. culicifacies, a sensitive, specific and cost effective high performance liquid chromatography (HPLC) method was developed, which is not influenced by the presence of biogenic amines, for the determination of NO2- and NO3- from mosquito mid-guts and haemolymph. Results This method is based on extraction, efficiency, assay reproducibility and contaminant minimization. It entails de-proteinization by centrifugal ultra filtration through ultracel 3 K filter and analysis by high performance anion exchange liquid chromatography (Sphereclone, 5 μ SAX column) with UV detection at 214 nm. The lower detection limit of the assay procedure is 50 pmoles in all midgut and haemolymph samples. Retention times for NO2- and NO3- in standards and in mid-gut samples were 3.42 and 4.53 min. respectively. Assay linearity for standards ranged between 50 nM and 1 mM. Recoveries of NO2- and NO3- from spiked samples (1–100 μM) and from the extracted standards (1–100 μM) were calculated to be 100%. Intra-assay and inter assay variations and relative standard deviations (RSDs) for NO2- and NO3- in spiked and un-spiked midgut samples were 5.7% or less. Increased levels NO2- and NO3- in midguts and haemolymph of An. culicifacies sibling species B in comparison to species A reflect towards a mechanism of refractoriness based on AcNOS physiology. Conclusion HPLC is a sensitive and accurate technique

  8. Plausibility of a subglacial lake under Amundsenisen Icefield (Svalbard): spatially variable water content and sensitivity to thermal effect of snow and firn layers.

    NASA Astrophysics Data System (ADS)

    Bucchignani, Edoardo; Mansutti, Daniela; Navarro, Francisco J.; Otero, Jaime; Glowacki, Piotr

    2013-04-01

    Within our study of the plausibility of a subglacial lake under the Amundsenisen Icefield in Southern Spitzbergen (Svalbard achipelago) (Glowacki et al., 2007), here we focus on the sensitivity of the system to the thermal effect of the firn and snow layers. Rough heat balance analysis shows that the firn layer plays an important role by driving the heat release to the atmosphere, so that its influence on the ice-water phase transition cannot be neglected (Bucchignani et al., 2012). We support our investigation with simulation via an in-house numerical code based on a thermomechanical transient model with dynamics given by a full Stokes system for the icefield and Large Eddy Simulation formulation for the water basin. Ice rheology is represented by Glen's law (n=3) with flow rate factor depending both on water content and temperature according to Breuer et al. (2006), for similar environments, and water content obtained from water mass balance (Greve & Blatter, 2009). Firn and snow thermal profiles are assumed to be steady. Their numerical values are partly (firn) available from Zagorodnov et al. (1985) and completed by matching the annual average air temperature at the surface. The ice-water phase interface is defined via the Stephan equation and the momentum and heat exchange between ice and water are regulated by corresponding interface jump conditions. We compare simulations performed with and without firn and snow layers. REFERENCES: P. Glowacki, A. Glazovsky, Y. Macheret, E. Vasilenko, J. Moore, J. O. Hagen, D. Puczko, M. Grabiec, J. Jania, F. Navarro, Dynamics and mass budget of Amundsenisen, Svalbard: interpretation of surface elevation and radar data, IUGG-2007, Perugia, 2007. E. Bucchignani, D. Mansutti, F.J. Navarro, J. Otero, P. Glowacki, Arguments from modelling about the existence of a subglacial lake at Amundsenisen Icefield (Svalbard), IGS-NB Meeting, 25-27 October, Stockholm, 2012. B. Breuer, M.A. Lange, N. Blindow, Sensitivity studies on model

  9. Amphiphiles for protein solubilization and stabilization

    DOEpatents

    Gellman, Samuel Helmer; Chae, Pil Seok; Laible, Philip D.; Wander, Marc J.

    2012-09-11

    The invention provides amphiphiles for manipulating membrane proteins. The amphiphiles can feature carbohydrate-derived hydrophilic groups and branchpoints in the hydrophilic moiety and/or in a lipophilic moiety. Such amphiphiles are useful as detergents for solubilization and stabilization of membrane proteins, including photosynthetic protein superassemblies obtained from bacterial membranes.

  10. Amphiphiles for protein solubilization and stabilization

    DOEpatents

    Gellman, Samuel Helmer; Chae, Pil Seok; Laible, Phillip D; Wander, Marc J

    2014-11-04

    The invention provides amphiphiles for manipulating membrane proteins. The amphiphiles can feature carbohydrate-derived hydrophilic groups and branchpoints in the hydrophilic moiety and/or in a lipophilic moiety. Such amphiphiles are useful as detergents for solubilization and stabilization of membrane proteins, including photosynthetic protein superassemblies obtained from bacterial membranes.

  11. Economic Stabilization Policies. Economic Topic Series.

    ERIC Educational Resources Information Center

    Lewis, Wilfred

    This pamphlet was derived from a discussion paper prepared for a Joint Council conference. It was specifically revised for this series to bring an important subject to the attention of students and concerned citizens. Part One defines the problem of economic stabilization and explains the fiscal and monetary measures used to help control the…

  12. Limits to Stability

    ERIC Educational Resources Information Center

    Cottey, Alan

    2012-01-01

    The author reflects briefly on what limited degree of global ecological stability and human cultural stability may be achieved, provided that humanity retains hope and does not give way to despair or hide in denial. These thoughts were triggered by a recent conference on International Stability and Systems Engineering. (Contains 5 notes.)

  13. Mimicking peroxidase activity by a polymer-supported oxidovanadium(IV) Schiff base complex derived from salicylaldehyde and 1,3-diamino-2-hydroxypropane.

    PubMed

    Maurya, Mannar R; Chaudhary, Nikita; Avecilla, Fernando; Correia, Isabel

    2015-06-01

    The polymer-supported oxidovanadium(IV) complex PS-[V(IV)O(sal-dahp)] (2) (PS=chloromethylated polystyrene crosslinked with 5% divinylbenzene, and H3sal-dahp=dibasic pentadentate ligand derived from salicylaldehyde and 1,3-diamino-2-hydroxypropane) was prepared from the corresponding monomeric oxidovanadium(IV) complex [V(IV)O(Hsal-dahp)(DMSO)] (1), characterized and successfully used as catalyst for the peroxidase-like oxidation of pyrogallol. The oxidation of pyrogallol to purpurogallin with PS-[V(IV)O(sal-dahp)] (2) was achieved under mild conditions at pH7 buffered solution. Plausible intermediate species formed during peroxidase mimicking experiments are proposed, by studying the model complex [V(IV)O(Hsal-dahp)(DMSO)] (1) by UV-visible and (51)V NMR spectroscopies. The high peroxidase mimicking ability of polymer-supported complex 2, its stability in a wide pH range, the easy separation from the reaction media, and the reusability without considerable decrease in activity, suggest that this heterogeneous catalyst has high potential for application in sustainable industrial catalysis. PMID:25747150

  14. Stability analysis of automobile driver steering control

    NASA Technical Reports Server (NTRS)

    Allen, R. W.

    1981-01-01

    In steering an automobile, the driver must basically control the direction of the car's trajectory (heading angle) and the lateral deviation of the car relative to a delineated pathway. A previously published linear control model of driver steering behavior which is analyzed from a stability point of view is considered. A simple approximate expression for a stability parameter, phase margin, is derived in terms of various driver and vehicle control parameters, and boundaries for stability are discussed. A field test study is reviewed that includes the measurement of driver steering control parameters. Phase margins derived for a range of vehicle characteristics are found to be generally consistent with known adaptive properties of the human operator. The implications of these results are discussed in terms of driver adaptive behavior.

  15. Orbital Stability of High Mass Planetary Systems

    NASA Astrophysics Data System (ADS)

    Morrison, Sarah J.; Kratter, Kaitlin M.

    2016-05-01

    In light of the observation of systems like HR 8799 that contain several planets with planet-star mass ratios larger than Jupiter's, we explore the relationships between planet separation, mass, and stability timescale for high mass multi-planet systems detectable via direct imaging. We discuss the role of overlap between 1st and sometimes 2nd order mean motion resonances, and show how trends in stability time vary from previous studies of lower mass multi-planet systems. We show that extrapolating empirically derived relationships between planet mass, separation, and stability timescale derived from lower mass planetary systems misestimate the stability timescales for higher mass planetary systems by more than an order of magnitude at separations near the Hill stability limit. We also address what metrics of planet separation are most useful for estimating a system's dynamical stability. We apply these results to young, gapped, debris disk systems of the ScoCen association in order to place limits on the maximum mass and number of planets that could persist for the lifetimes of the disks. These efforts will provide useful constraints for on-going direct imaging surveys. By setting upper limits on the most easily detectable systems, we can better interpret both new discoveries and non-dectections.

  16. Epigenetic Stability of Cryopreserved and Cold-Stored Hops

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Three hop accessions representative of commercially cultivated hops were selected for the analysis of epigenetic stability; females of different origins, including a cultivar developed in New Zealand (Calicross) from American cultivars, a landrace derived European cultivar (Tardif de Bourgogne), and...

  17. Effects of asymmetry on the dynamic stability of aircraft

    NASA Technical Reports Server (NTRS)

    Fantino, R. E.; Parsons, E. K.; Powell, J. D.; Shevell, R. S.

    1975-01-01

    The oblique wing concept for transonic aircraft was proposed to reduce drag. The dynamic stability of the aircraft was investigated by analytically determining the stability derivatives at angles of skew ranging from 0 and 45 deg and using these stability derivatives in a linear analysis of the coupled aircraft behavior. The stability derivatives were obtained using a lifting line aerodynamic theory and found to give reasonable agreement with derivatives developed in a previous study for the same aircraft. In the dynamic analysis, no instability or large changes occurred in the root locations for skew angles varying from 0 to 45 deg with the exception of roll convergence. The damping in roll, however, decreased by an order of magnitude. Rolling was a prominent feature of all the oscillatory mode shapes at high skew angles.

  18. Fine-Tuning and the Stability of Recurrent Neural Networks

    PubMed Central

    MacNeil, David; Eliasmith, Chris

    2011-01-01

    A central criticism of standard theoretical approaches to constructing stable, recurrent model networks is that the synaptic connection weights need to be finely-tuned. This criticism is severe because proposed rules for learning these weights have been shown to have various limitations to their biological plausibility. Hence it is unlikely that such rules are used to continuously fine-tune the network in vivo. We describe a learning rule that is able to tune synaptic weights in a biologically plausible manner. We demonstrate and test this rule in the context of the oculomotor integrator, showing that only known neural signals are needed to tune the weights. We demonstrate that the rule appropriately accounts for a wide variety of experimental results, and is robust under several kinds of perturbation. Furthermore, we show that the rule is able to achieve stability as good as or better than that provided by the linearly optimal weights often used in recurrent models of the integrator. Finally, we discuss how this rule can be generalized to tune a wide variety of recurrent attractor networks, such as those found in head direction and path integration systems, suggesting that it may be used to tune a wide variety of stable neural systems. PMID:21980334

  19. Stable Hemiaminals: 2-Aminopyrimidine Derivatives.

    PubMed

    Kwiecień, Anna; Ciunik, Zbigniew

    2015-01-01

    Stable hemiaminals can be obtained in the one-pot reaction between 2-aminopyrimidine and nitrobenzaldehyde derivatives. Ten new hemiaminals have been obtained, six of them in crystal state. The molecular stability of these intermediates results from the presence of both electron-withdrawing nitro groups as substituents on the phenyl ring and pyrimidine ring, so no further stabilisation by intramolecular interaction is required. Hemiaminal molecules possess a tetrahedral carbon atom constituting a stereogenic centre. As the result of crystallisation in centrosymmetric space groups both enantiomers are present in the crystal structure. PMID:26258772

  20. Asymptotic vacua with higher derivatives

    NASA Astrophysics Data System (ADS)

    Cotsakis, Spiros; Kadry, Seifedine; Kolionis, Georgios; Tsokaros, Antonios

    2016-04-01

    We study limits of vacuum, isotropic universes in the full, effective, four-dimensional theory with higher derivatives. We show that all flat vacua as well as general curved ones are globally attracted by the standard, square root scaling solution at early times. Open vacua asymptote to horizon-free, Milne states in both directions while closed universes exhibit more complex logarithmic singularities, starting from initial data sets of a possibly smaller dimension. We also discuss the relation of our results to the asymptotic stability of the passage through the singularity in ekpyrotic and cyclic cosmologies.