WorldWideScience

Sample records for perturbations initially seeded

  1. Seeded perturbations in wire array z-pinches

    International Nuclear Information System (INIS)

    Robinson, Allen Conrad; Kantsyrev, Victor Leonidovich; Wunsch, Scott Edward; Oliver, Bryan Velten; Lebedev, Sergey V.; Safronova, Alla S.; Maxwell, J.; McKenney, John Lee; Ampleford, David J.; Rapley, J.; Bott, S.C.; Palmer, J.B.A.; Bland, Simon Nicholas; Jones, Brent Manley; Chittenden, Jeremy Paul; Garasi, Christopher Joseph; Hall, Gareth Neville; Mehlhorn, Thomas Alan; Deeney, Christopher

    2004-01-01

    The impact of 3D structure on wire array z-pinch dynamics is a topic of current interest, and has been studied by the controlled seeding of wire perturbations. First, Al wires were etched at Sandia, creating 20% radial perturbations with variable axial wavelength. Observations of magnetic bubble formation in the etched regions during experiments on the MAGPIE accelerator are discussed and compared to 3D MHD modeling. Second, thin NaF coatings of 1 mm axial extent were deposited on Al wires and fielded on the Zebra accelerator. Little or no axial transport of the NaF spectroscopic dopant was observed in spatially resolved K-shell spectra, which places constraints on particle diffusivity in dense z-pinch plasmas. Finally, technology development for seeding perturbations is discussed

  2. Seeded perturbations in wire array Z-Pinches

    International Nuclear Information System (INIS)

    Robinson, Allen Conrad; Fedin, Dmitry; Kantsyrev, Victor Leonidovich; Wunsch, Scott Edward; Oliver, Bryan Velten; Lebedev, Sergey V.; Coverdale, Christine Anne; Ouart, Nicholas D.; LePell, Paul David; Safronova, Alla S.; Shrestha, I.; McKenney, John Lee; Ampleford, David J.; Rapley, J.; Bott, S.C.; Palmer, J.B.A.; Sotnikov, Vladimir Isaakovich; Bland, Simon Nicholas; Ivanov, Vladimir V.; Chittenden, Jeremy Paul; Jones, B.; Garasi, Christopher Joseph; Hall, Gareth Neville; Yilmaz, M. Faith; Mehlhorn, Thomas Alan; Deeney, Christopher; Pokala, S.; Nalajala, V.

    2005-01-01

    Controlled seeding of perturbations is employed to study the evolution of wire array z-pinch implosion instabilities which strongly impact x-ray production when the 3D plasma stagnates on axis. Wires modulated in radius exhibit locally enhanced magnetic field and imploding bubble formation at discontinuities in wire radius due to the perturbed current path. Wires coated with localized spectroscopic dopants are used to track turbulent material flow. Experiments and MHD modeling offer insight into the behavior of z-pinch instabilities.

  3. The SEED Initiative

    Science.gov (United States)

    Teich, Carolyn R.

    2011-01-01

    Committed to fulfilling the promise of the green economy, the American Association of Community Colleges (AACC) launched the Sustainability Education and Economic Development (SEED) initiative (www.theseedcenter.org) in October 2010. The project advances sustainability and clean energy workforce development practices at community colleges by…

  4. Effect of initial perturbation amplitude on Richtmyer-Meshkov flows induced by strong shocks

    Energy Technology Data Exchange (ETDEWEB)

    Dell, Z.; Abarzhi, S. I., E-mail: snezhana.abarzhi@gmail.com, E-mail: sabarji@andrew.cmu.edu [Mellon College of Science and Carnegie Mellon University – Qatar, Carnegie Mellon University, Pittsburgh, Pennsylvania 15231 (United States); Stellingwerf, R. F. [Stellingwerf Consulting, Huntsville, Alabama 35803 (United States)

    2015-09-15

    We systematically study the effect of the initial perturbation on Richtmyer-Meshkov (RM) flows induced by strong shocks in fluids with contrasting densities. Smooth Particle Hydrodynamics simulations are employed. A broad range of shock strengths and density ratios is considered. The amplitude of the initial single mode sinusoidal perturbation of the interface varies from 0% to 100% of its wavelength. The simulations results are compared, wherever possible, with four rigorous theories, and with other experiments and simulations, achieving good quantitative and qualitative agreement. Our study is focused on early time dynamics of the Richtmyer-Meshkov instability (RMI). We analyze the initial growth-rate of RMI immediately after the shock passage, when the perturbation amplitude increases linearly with time. For the first time, to the authors' knowledge, we find that the initial growth-rate of RMI is a non-monotone function of the initial perturbation amplitude, thus restraining the amount of energy that can be deposited by the shock at the interface. The maximum value of the initial growth-rate depends on the shock strength and the density ratio, whereas the corresponding value of the initial perturbation amplitude depends only slightly on the shock strength and density ratio.

  5. Faith in a seed: on the origins of equatorial plasma bubbles

    Directory of Open Access Journals (Sweden)

    J. M. Retterer

    2014-05-01

    Full Text Available Our faith in the seeds of equatorial plasma irregularities holds that there will generally always be density perturbations sufficient to provide the seeds for irregularity development whenever the Rayleigh–Taylor instability is active. When the duration of the time of the Rayleigh–Taylor instability is short, however, the magnitude of the seed perturbations can make a difference in whether the irregularities have a chance to grow to a strength at which the nonlinear development of plumes occurs. In addition, the character of the resulting irregularities reflects the characteristics of the initial seed density perturbation, e.g., their strength, spacing, and, to some extent, their spatial scales, and it is important to know the seeds to help determine the structure of the developed irregularities. To this end, we describe the climatology of daytime and early-evening density irregularities that can serve as seeds for later development of plumes, as determined from the Planar Langmuir Probe (PLP plasma density measurements on the C/NOFS (Communication and Navigation Outage Forecast System satellite mission, presenting their magnitude as a function of altitude, latitude, longitude, local time, season, and phase in the solar cycle (within the C/NOFS observation era. To examine some of the consequences of these density perturbations, they are used as initial conditions for the PBMOD PBMOD (Retterer, 2010a 3-D irregularity model to follow their potential development into larger-amplitude irregularities, plumes, and radio scintillation. "Though I do not believe that a pla[sma bubble] will spring up where no seed has been, I have great faith in a seed. Convince me that you have a seed there, and I am prepared to expect wonders." – Henry David Thoreau

  6. The relative importance of seed competition, resource competition and perturbations on community structure

    Directory of Open Access Journals (Sweden)

    K. Bohn

    2011-05-01

    Full Text Available While the regional climate is the primary selection pressure for whether a plant strategy can survive, however, competitive interactions strongly affect the relative abundances of plant strategies within communities. Here, we investigate the relative importance of competition and perturbations on the development of vegetation community structure. To do so, we develop DIVE (Dynamics and Interactions of VEgetation, a simple general model that links plant strategies to their competitive dynamics, using growth and reproduction characteristics that emerge from climatic constraints. The model calculates population dynamics based on establishment, mortality, invasion and exclusion in the presence of different strengths of perturbations, seed and resource competition. The highest levels of diversity were found in simulations without competition as long as mortality is not too high. However, reasonable successional dynamics were only achieved when resource competition is considered. Under high levels of competition, intermediate levels of perturbations were required to obtain coexistence. Since succession and coexistence are observed in plant communities, we conclude that the DIVE model with competition and intermediate levels of perturbation represents an adequate way to model population dynamics. Because of the simplicity and generality of DIVE, it could be used to understand vegetation structure and functioning at the global scale and the response of vegetation to global change.

  7. Initial conditions for cosmological perturbations

    Science.gov (United States)

    Ashtekar, Abhay; Gupt, Brajesh

    2017-02-01

    Penrose proposed that the big bang singularity should be constrained by requiring that the Weyl curvature vanishes there. The idea behind this past hypothesis is attractive because it constrains the initial conditions for the universe in geometric terms and is not confined to a specific early universe paradigm. However, the precise statement of Penrose’s hypothesis is tied to classical space-times and furthermore restricts only the gravitational degrees of freedom. These are encapsulated only in the tensor modes of the commonly used cosmological perturbation theory. Drawing inspiration from the underlying idea, we propose a quantum generalization of Penrose’s hypothesis using the Planck regime in place of the big bang, and simultaneously incorporating tensor as well as scalar modes. Initial conditions selected by this generalization constrain the universe to be as homogeneous and isotropic in the Planck regime as permitted by the Heisenberg uncertainty relations.

  8. Initial conditions for cosmological perturbations

    International Nuclear Information System (INIS)

    Ashtekar, Abhay; Gupt, Brajesh

    2017-01-01

    Penrose proposed that the big bang singularity should be constrained by requiring that the Weyl curvature vanishes there. The idea behind this past hypothesis is attractive because it constrains the initial conditions for the universe in geometric terms and is not confined to a specific early universe paradigm. However, the precise statement of Penrose’s hypothesis is tied to classical space-times and furthermore restricts only the gravitational degrees of freedom. These are encapsulated only in the tensor modes of the commonly used cosmological perturbation theory. Drawing inspiration from the underlying idea, we propose a quantum generalization of Penrose’s hypothesis using the Planck regime in place of the big bang, and simultaneously incorporating tensor as well as scalar modes. Initial conditions selected by this generalization constrain the universe to be as homogeneous and isotropic in the Planck regime as permitted by the Heisenberg uncertainty relations . (paper)

  9. Sensitivity of decadal predictions to the initial atmospheric and oceanic perturbations

    Energy Technology Data Exchange (ETDEWEB)

    Du, H.; Garcia-Serrano, J.; Guemas, V.; Soufflet, Y. [Institut Catala de Ciencies del Clima (IC3), Barcelona (Spain); Doblas-Reyes, F.J. [Institut Catala de Ciencies del Clima (IC3), Barcelona (Spain); Institucio Catalana de Recerca i Estudis Avancats (ICREA), Barcelona (Spain); Wouters, B. [Royal Netherlands Meteorological Institute (KNMI), De Bilt (Netherlands)

    2012-10-15

    A coupled global atmosphere-ocean model is employed to investigate the impact of initial perturbation methods on the behaviour of five-member ensemble decadal re-forecasts. Three initial-condition perturbation strategies, atmosphere only, ocean only and atmosphere-ocean, have been used and the impact on selected variables have been investigated. The impact has been assessed in terms of climate drift, forecast quality and spread. The simulated global means of near-surface air temperature (T2M), sea surface temperature (SST) and sea ice area (SIA) for both Arctic and Antarctic show reasonably good quality, in spite of the non-negligible drift of the model. The skill in terms of correlation is not significantly affected by the particular perturbation method employed. The ensemble spread generated for T2M, SST and land surface precipitation (PCP) saturates quickly with any of the perturbation methods. However, for SIA, Atlantic meridional overturning circulation (AMOC) and ocean heat content (OHC), the spread increases substantially during the forecast time when ocean perturbations are applied. Ocean perturbations are particularly important for Antarctic SIA and OHC for the middle and deep layers of the ocean. The results will be helpful in the design of ensemble prediction experiments. (orig.)

  10. Radiofrequency initiation and radiofrequency sustainment of laser initiated seeded high pressure plasma

    International Nuclear Information System (INIS)

    Paller, Eric S.; Scharer, John E.; Akhtar, Kamran; Kelly, Kurt; Ding, Guowen

    2001-01-01

    We examine radiofrequency initiation of high pressure(1-70 Torr) inductive plasma discharges in argon, nitrogen, air and organic seed gas mixtures. Millimeter wave interferometry, optical emission and antenna wave impedance measurements for double half-turn helix and helical inductive antennas are used to interpret the rf/plasma coupling, measure the densities in the range of 10 12 cm -3 and analyze the ionization and excited states of the gas mixtures. We have also carried out 193 nm excimer laser initiation of an organic gas seed plasma which is sustained at higher pressures(150 Torr) by radiofrequency coupling at 2.8 kW power levels

  11. Dynamics of seed magnetic island formation due to geometrically coupled perturbations

    International Nuclear Information System (INIS)

    Hegna, C.C.; Callen, J.D.; LaHaye, R.J.

    1998-06-01

    Seed magnetic island formation due to a dynamically growing external source in toroidal confinement devices is modeled as an initial value forced reconnection problem. For an external source whose amplitude grows on a time scale quickly compared to the Sweet-Parker time of resistive magnetohydrodynamics, the induced reconnection is characterized by a current sheet and a reconnected flux amplitude which lags in time the source amplitude. This suggests that neoclassical tearing modes, whose excitation requires a seed magnetic island, are more difficult to cause in high Lundquist number plasmas

  12. Freeing Crop Genetics through the Open Source Seed Initiative.

    Directory of Open Access Journals (Sweden)

    Claire H Luby

    2016-04-01

    Full Text Available For millennia, seeds have been freely available to use for farming and plant breeding without restriction. Within the past century, however, intellectual property rights (IPRs have threatened this tradition. In response, a movement has emerged to counter the trend toward increasing consolidation of control and ownership of plant germplasm. One effort, the Open Source Seed Initiative (OSSI, www.osseeds.org, aims to ensure access to crop genetic resources by embracing an open source mechanism that fosters exchange and innovation among farmers, plant breeders, and seed companies. Plant breeders across many sectors have taken the OSSI Pledge to create a protected commons of plant germplasm for future generations.

  13. Freeing Crop Genetics through the Open Source Seed Initiative.

    Science.gov (United States)

    Luby, Claire H; Goldman, Irwin L

    2016-04-01

    For millennia, seeds have been freely available to use for farming and plant breeding without restriction. Within the past century, however, intellectual property rights (IPRs) have threatened this tradition. In response, a movement has emerged to counter the trend toward increasing consolidation of control and ownership of plant germplasm. One effort, the Open Source Seed Initiative (OSSI, www.osseeds.org), aims to ensure access to crop genetic resources by embracing an open source mechanism that fosters exchange and innovation among farmers, plant breeders, and seed companies. Plant breeders across many sectors have taken the OSSI Pledge to create a protected commons of plant germplasm for future generations.

  14. On Perturbative Cubic Nonlinear Schrodinger Equations under Complex Nonhomogeneities and Complex Initial Conditions

    Directory of Open Access Journals (Sweden)

    Magdy A. El-Tawil

    2009-01-01

    Full Text Available A perturbing nonlinear Schrodinger equation is studied under general complex nonhomogeneities and complex initial conditions for zero boundary conditions. The perturbation method together with the eigenfunction expansion and variational parameters methods are used to introduce an approximate solution for the perturbative nonlinear case for which a power series solution is proved to exist. Using Mathematica, the symbolic solution algorithm is tested through computing the possible approximations under truncation procedures. The method of solution is illustrated through case studies and figures.

  15. Perturbative expansion and the initial value problem of the K.d.V. equations

    International Nuclear Information System (INIS)

    Turchetti, G.

    1980-01-01

    For the potential K.d.V. equation is considered a perturbation expansion in which the initial condition is imposed on the zeroth order term. The N soliton solutions turn out to be rational functions in the expansion parameter so that the perturbation series can be exactly summed by the [N-1/N] Pade approximants; moreover the [n-1/n] and [n/n] Pade approximants for n [pt

  16. A Simple Density with Distance Based Initial Seed Selection Technique for K Means Algorithm

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    Sajidha Syed Azimuddin

    2017-01-01

    Full Text Available Open issues with respect to K means algorithm are identifying the number of clusters, initial seed concept selection, clustering tendency, handling empty clusters, identifying outliers etc. In this paper we propose a novel and a simple technique considering both density and distance of the concepts in a dataset to identify initial seed concepts for clustering. Many authors have proposed different techniques to identify initial seed concepts; but our method ensures that the initial seed concepts are chosen from different clusters that are to be generated by the clustering solution. The hallmark of our algorithm is that it is a single pass algorithm that does not require any extra parameters to be estimated. Further, our seed concepts are one among the actual concepts and not the mean of representative concepts as is the case in many other algorithms. We have implemented our proposed algorithm and compared the results with the interval based technique of Fouad Khan. We see that our method outperforms the interval based method. We have also compared our method with the original random K means and K Means++ algorithms.

  17. Variational Homotopy Perturbation Method for Solving Higher Dimensional Initial Boundary Value Problems

    Directory of Open Access Journals (Sweden)

    Muhammad Aslam Noor

    2008-01-01

    Full Text Available We suggest and analyze a technique by combining the variational iteration method and the homotopy perturbation method. This method is called the variational homotopy perturbation method (VHPM. We use this method for solving higher dimensional initial boundary value problems with variable coefficients. The developed algorithm is quite efficient and is practically well suited for use in these problems. The proposed scheme finds the solution without any discritization, transformation, or restrictive assumptions and avoids the round-off errors. Several examples are given to check the reliability and efficiency of the proposed technique.

  18. Transients from initial conditions based on Lagrangian perturbation theory in N-body simulations II: the effect of the transverse mode

    International Nuclear Information System (INIS)

    Tatekawa, Takayuki

    2014-01-01

    We study the initial conditions for cosmological N-body simulations for precision cosmology. In general, Zel'dovich approximation has been applied for the initial conditions of N-body simulations for a long time. These initial conditions provide incorrect higher-order growth. These error caused by setting up the initial conditions by perturbation theory is called transients. We investigated the impact of transient on non-Gaussianity of density field by performing cosmological N-body simulations with initial conditions based on first-, second-, and third-order Lagrangian perturbation theory in previous paper. In this paper, we evaluates the effect of the transverse mode in the third-order Lagrangian perturbation theory for several statistical quantities such as power spectrum and non-Gaussianty. Then we clarified that the effect of the transverse mode in the third-order Lagrangian perturbation theory is quite small

  19. SU-E-T-378: Evaluation of An Analytical Model for the Inter-Seed Attenuation Effect in 103-Pd Multi-Seed Implant Brachytherapy

    Energy Technology Data Exchange (ETDEWEB)

    Safigholi, H; Soliman, A; Song, W [Sunnybrook Research Institute, Sunnybrook Health Sciences Centre, U of T, Toronto, Ontario (Canada); Meigooni, A Soleimani [Comprehensive Cancer Center of Nevada, Las Vegas, Nevada (United States); Han, D [Sunnybrook Research Institute, Sunnybrook Health Sciences Centre, U of T, Toronto, Ontario (Canada); University of California, San Diego, La Jolla, CA (United States)

    2015-06-15

    Purpose: Brachytherapy treatment planning systems based on TG-43 protocol calculate the dose in water and neglects the heterogeneity effect of seeds in multi-seed implant brachytherapy. In this research, the accuracy of a novel analytical model that we propose for the inter-seed attenuation effect (ISA) for 103-Pd seed model is evaluated. Methods: In the analytical model, dose perturbation due to the ISA effect for each seed in an LDR multi-seed implant for 103-Pd is calculated by assuming that the seed of interest is active and the other surrounding seeds are inactive. The cumulative dosimetric effect of all seeds is then summed using the superposition principle. The model is based on pre Monte Carlo (MC) simulated 3D kernels of the dose perturbations caused by the ISA effect. The cumulative ISA effect due to multiple surrounding seeds is obtained by a simple multiplication of the individual ISA effect by each seed, the effect of which is determined by the distance from the seed of interest. This novel algorithm is then compared with full MC water-based simulations (FMCW). Results: The results show that the dose perturbation model we propose is in excellent agreement with the FMCW values for a case with three seeds separated by 1 cm. The average difference of the model and the FMCW simulations was less than 8%±2%. Conclusion: Using the proposed novel analytical ISA effect model, one could expedite the corrections due to the ISA dose perturbation effects during permanent seed 103-Pd brachytherapy planning with minimal increase in time since the model is based on multiplications and superposition. This model can be applied, in principle, to any other brachytherapy seeds. Further work is necessary to validate this model on a more complicated geometry as well.

  20. Topology of large-scale structure in seeded hot dark matter models

    Science.gov (United States)

    Beaky, Matthew M.; Scherrer, Robert J.; Villumsen, Jens V.

    1992-01-01

    The topology of the isodensity surfaces in seeded hot dark matter models, in which static seed masses provide the density perturbations in a universe dominated by massive neutrinos is examined. When smoothed with a Gaussian window, the linear initial conditions in these models show no trace of non-Gaussian behavior for r0 equal to or greater than 5 Mpc (h = 1/2), except for very low seed densities, which show a shift toward isolated peaks. An approximate analytic expression is given for the genus curve expected in linear density fields from randomly distributed seed masses. The evolved models have a Gaussian topology for r0 = 10 Mpc, but show a shift toward a cellular topology with r0 = 5 Mpc; Gaussian models with an identical power spectrum show the same behavior.

  1. Regarding the perturbed operating process of DB propellant rocket motor at extreme initial grain temperatures

    Directory of Open Access Journals (Sweden)

    Ioan ION

    2012-03-01

    Full Text Available Despite many decades of study, the combustion instability of several DB propellants is still of particular concern, especially at extreme grain temperature conditions of rocket motor operating. The purpose of the first part of the paper is to give an overview of our main experimental results on combustion instabilities and pressure oscillations in DB propellant segmented grain rocket motors (SPRM-01, large L/D ratio, working at extreme initial grain temperatures. Thus, we recorded some particular pressure-time traces with significant perturbed pressure signal that was FFT analysed. An updated mathematical model incorporating transient frequency-dependent combustion response, in conjunction with pressure-dependent burning, is applied to investigate and predict the DB propellant combustion instability phenomenon. The susceptibility of the tested motor SPRM-01 with DB propellant to get a perturbed working and to go unstable with pressure was evidenced and this risk has to be evaluated. In the last part of our paper we evaluated the influence of recorded perturbed thrust on the rocket behaviour on the trajectory. The study revealed that at firing-table initial conditions, this kind of perturbed motor operating may not lead to an unstable rocket flight, but the ballistic parameters would be influenced in an unacceptable manner.

  2. Seeds and plantlets of Myrciaria dubia “camu-camu”: biometry, germination, and initial growth

    Directory of Open Access Journals (Sweden)

    Anderson E. Medina Bardales

    2014-06-01

    Full Text Available The objectives were to determine seed biometrics, recording cellular respiration in the imbibition process, evaluate the effect of inducing chemicals in germination and early growth analysis. Cellular respiration during imbibition was measured by reduction of methylene blue and Janus Green B. The inductor effect of five chemical compounds in germination was evaluated. Initial growth was recorded by stereoscopic. Results showed that the seeds have an average weight of 520 ± 172 mg, length of 13.50 ± 1.76 mm, width of 10.61 ± 1.14 mm, and thickness of 4.68 ± 0 62 mm. These variables showed significant correlations (r of 0.494 to 0.897 and p 90% and 65% respectively. Seedling initial growth consisted of six stages and occurred over a period of 22 days after radicle emergence. In conclusion, M. dubia seeds show wide variation in their biometrics (weight, length, width and thickness, but show significant correlations with each other. Likewise, seeds are metabolically active in imbibition process, and germination is induced by sodium nitrite and potassium cyanide. Furthermore, seedling initial growth to occur over a period of 22 days after emergence of the radicle and consists of six distinct stages.

  3. Optimal Initial Perturbations for Ensemble Prediction of the Madden-Julian Oscillation during Boreal Winter

    Science.gov (United States)

    Ham, Yoo-Geun; Schubert, Siegfried; Chang, Yehui

    2012-01-01

    An initialization strategy, tailored to the prediction of the Madden-Julian oscillation (MJO), is evaluated using the Goddard Earth Observing System Model, version 5 (GEOS-5), coupled general circulation model (CGCM). The approach is based on the empirical singular vectors (ESVs) of a reduced-space statistically determined linear approximation of the full nonlinear CGCM. The initial ESV, extracted using 10 years (1990-99) of boreal winter hindcast data, has zonal wind anomalies over the western Indian Ocean, while the final ESV (at a forecast lead time of 10 days) reflects a propagation of the zonal wind anomalies to the east over the Maritime Continent an evolution that is characteristic of the MJO. A new set of ensemble hindcasts are produced for the boreal winter season from 1990 to 1999 in which the leading ESV provides the initial perturbations. The results are compared with those from a set of control hindcasts generated using random perturbations. It is shown that the ESV-based predictions have a systematically higher bivariate correlation skill in predicting the MJO compared to those using the random perturbations. Furthermore, the improvement in the skill depends on the phase of the MJO. The ESV is particularly effective in increasing the forecast skill during those phases of the MJO in which the control has low skill (with correlations increasing by as much as 0.2 at 20 25-day lead times), as well as during those times in which the MJO is weak.

  4. Hydro-instability growth of perturbation seeds from alternate capsule-support strategies in indirect-drive implosions on National Ignition Facility

    Science.gov (United States)

    Martinez, D. A.; Smalyuk, V. A.; MacPhee, A. G.; Milovich, J.; Casey, D. T.; Weber, C. R.; Robey, H. F.; Chen, K.-C.; Clark, D. S.; Crippen, J.; Farrell, M.; Felker, S.; Field, J. E.; Haan, S. W.; Hammel, B. A.; Hamza, A. V.; Stadermann, M.; Hsing, W. W.; Kroll, J. J.; Landen, O. L.; Nikroo, A.; Pickworth, L.; Rice, N.

    2017-10-01

    Hydrodynamic instability growth of the capsule support membranes (or "tents") and fill tubes has been studied in spherical, glow discharge polymer plastic capsule implosions at the National Ignition Facility (NIF) [Campbell et al., AIP Conf. Proc. 429, 3 (1998)]. In NIF implosions, the capsules are supported by tents because the nominal 10-μm thick fill tubes are not strong enough to support capsules by themselves. After it was recognized that the tents had a significant impact of implosion stability, new support methods were investigated, including thicker, 30-μm diameter fill tubes and cantilevered fill tubes, as described in this article. A new "sub-scale" version of the existing x-ray radiography platform was developed for measuring growing capsule perturbations in the acceleration phase of implosions. It was calibrated using hydrodynamic growth measurements of pre-imposed capsule modulations with Legendre modes of 60, 90, 110, and 140 at convergence ratios up to ˜2.4. Subsequent experiments with 3-D perturbations have studied instability growth of 10-μm and 30-μm thick fill tubes to compare them with 30-nm thick tent perturbations at convergence ratios up to ˜3. In other experiments, the perturbations from cantilevered fill tubes were measured and compared to the tent perturbations. The cantilevered fill tubes were supported by 12-μm thick SiC rods, offset by 100 μm, 200 μm, and 300 μm from the capsule surfaces. Based on these experiments, 30-μm thick fill tubes and 300-μm offset cantilevered fill tubes were recommended for further tests using layered deuterium-tritium implosions. The effects of x-ray shadowing during the drive and oxygen-induced perturbations during target assembly produced additional seeds for instabilities and were also measured in these experiments.

  5. HFR1 Sequesters PIF1 to Govern the Transcriptional Network Underlying Light-Initiated Seed Germination in Arabidopsis[C][W][OPEN

    Science.gov (United States)

    Shi, Hui; Zhong, Shangwei; Mo, Xiaorong; Liu, Na; Nezames, Cynthia D.; Deng, Xing Wang

    2013-01-01

    Seed germination is the first step for seed plants to initiate a new life cycle. Light plays a predominant role in promoting seed germination, where the initial phase is mediated by photoreceptor phytochrome B (phyB). Previous studies showed that PHYTOCHROME-INTERACTING FACTOR1 (PIF1) represses seed germination downstream of phyB. Here, we identify a positive regulator of phyB-dependent seed germination, LONG HYPOCOTYL IN FAR-RED1 (HFR1). HFR1 blocks PIF1 transcriptional activity by forming a heterodimer with PIF1 that prevents PIF1 from binding to DNA. Our whole-genomic analysis shows that HFR1 and PIF1 oppositely mediate the light-regulated transcriptome in imbibed seeds. Through the HFR1–PIF1 module, light regulates expression of numerous genes involved in cell wall loosening, cell division, and hormone pathways to initiate seed germination. The functionally antagonistic HFR1–PIF1 pair constructs a fail-safe mechanism for fine-tuning seed germination during low-level illumination, ensuring a rapid response to favorable environmental changes. This study identifies the HFR1–PIF1 pair as a central module directing the whole genomic transcriptional network to rapidly initiate light-induced seed germination. PMID:24179122

  6. Effects of ocean initial perturbation on developing phase of ENSO in a coupled seasonal prediction model

    Science.gov (United States)

    Lee, Hyun-Chul; Kumar, Arun; Wang, Wanqiu

    2018-03-01

    Coupled prediction systems for seasonal and inter-annual variability in the tropical Pacific are initialized from ocean analyses. In ocean initial states, small scale perturbations are inevitably smoothed or distorted by the observational limits and data assimilation procedures, which tends to induce potential ocean initial errors for the El Nino-Southern Oscillation (ENSO) prediction. Here, the evolution and effects of ocean initial errors from the small scale perturbation on the developing phase of ENSO are investigated by an ensemble of coupled model predictions. Results show that the ocean initial errors at the thermocline in the western tropical Pacific grow rapidly to project on the first mode of equatorial Kelvin wave and propagate to the east along the thermocline. In boreal spring when the surface buoyancy flux weakens in the eastern tropical Pacific, the subsurface errors influence sea surface temperature variability and would account for the seasonal dependence of prediction skill in the NINO3 region. It is concluded that the ENSO prediction in the eastern tropical Pacific after boreal spring can be improved by increasing the observational accuracy of subsurface ocean initial states in the western tropical Pacific.

  7. Isocurvature perturbations in the Ekpyrotic Universe

    International Nuclear Information System (INIS)

    Notari, A.; Riotto, A.

    2002-01-01

    The Ekpyrotic scenario assumes that our visible Universe is a boundary brane in a five-dimensional bulk and that the hot Big Bang occurs when a nearly supersymmetric five-brane travelling along the fifth dimension collides with our visible brane. We show that the generation of isocurvature perturbations is a generic prediction of the Ekpyrotic Universe. This is due to the interactions in the kinetic terms between the brane modulus parameterizing the position of the five-brane in the bulk and the dilaton and volume moduli. We show how to separate explicitly the adiabatic and isocurvature modes by performing a rotation in field space. Our results indicate that adiabatic and isocurvature perturbations might be cross-correlated and that curvature perturbations might be entirely seeded by isocurvature perturbations

  8. Non-Vacuum Initial States for Cosmological Perturbations of Quantum-Mechanical Origin

    CERN Document Server

    Martín, J; Sakellariadou, M; Martin, Jerome; Riazuelo, Alain; Sakellariadou, Mairi

    2000-01-01

    In the context of inflation, non-vacuum initial states for cosmological perturbations that possess a built in scale are studied. It is demonstrated that this assumption leads to a falsifiable class of models. The question of whether they lead to conflicts with the available observations is addressed. For this purpose, the power spectrum of the Bardeen potential operator is calculated and compared with the CMBR anisotropies measurements and the redshift surveys of galaxies and clusters of galaxies. Generic predictions of the model are: a high first acoustic peak, the presence of a bump in the matter power spectrum and non-Gaussian statistics. The details are controlled by the number of quanta in the non-vacuum initial state. Comparisons with observations show that there exists a window for the free parameters such that good agreement between the data and the theoretical predictions is possible. However, in the case where the initial state is a state with a fixed number of quanta, it is shown that this number c...

  9. Perturbation theory

    International Nuclear Information System (INIS)

    Bartlett, R.; Kirtman, B.; Davidson, E.R.

    1978-01-01

    After noting some advantages of using perturbation theory some of the various types are related on a chart and described, including many-body nonlinear summations, quartic force-field fit for geometry, fourth-order correlation approximations, and a survey of some recent work. Alternative initial approximations in perturbation theory are also discussed. 25 references

  10. Perturbation analysis of spontaneous action potential initiation by stochastic ion channels

    KAUST Repository

    Keener, James P.

    2011-07-01

    A stochastic interpretation of spontaneous action potential initiation is developed for the Morris-Lecar equations. Initiation of a spontaneous action potential can be interpreted as the escape from one of the wells of a double well potential, and we develop an asymptotic approximation of the mean exit time using a recently developed quasistationary perturbation method. Using the fact that the activating ionic channel\\'s random openings and closings are fast relative to other processes, we derive an accurate estimate for the mean time to fire an action potential (MFT), which is valid for a below-threshold applied current. Previous studies have found that for above-threshold applied current, where there is only a single stable fixed point, a diffusion approximation can be used. We also explore why different diffusion approximation techniques fail to estimate the MFT. © 2011 American Physical Society.

  11. METHODS FOR OVERCOMING SEED DORMANCY AND THE INITIAL GROWTH OF Ziziphus joazeiro Mart. IN DIFFERENT SOILS

    Directory of Open Access Journals (Sweden)

    JOSENARA DAIANE DE SOUZA COSTA

    2016-01-01

    Full Text Available Considering the potential and importance of biodiversity of the Caatinga biome, studies on endemic species are relevant to conservation of its natural resources. The objectives of this work was to evaluate seed viability and physical methods for overcoming seed dormancy in juazeiro (Ziziphus joazeiro Mart. and assess the influence of different types of soil on the initial growth of juazeiro plants. The experiments were conducted in three stages. In the first stage, the viability of seeds from different lots was evaluated using the tetrazolium test. The second stage was conducted in a plant nursery, evaluating the application of physical processes (scarification with sandpaper and hammer in overcoming seed dormancy, and the initial growth of the plants. In the third step, the chlorophyll a and b contents, gas exchange and dry matter accumulation were evaluated in young juazeiro plants in three types of soil (Oxisol, Entisol and Vertisol. The results indicate that the viability of juazeiro seeds is greatly influenced by differences between the progenitor plants and by storage conditions, which enable a longevity of two years when stored at 22°C and 16% of relative humidity. The scarification methods with sandpaper and hammer are not efficient to reduce the time and uniform seed germination. The juazeiro plants have high growth potential in different edaphic environments, adapting well to soils of different textures and chemical compositions.

  12. Dynamics of the cavity radiation of a correlated emission laser initially seeded with a thermal light

    Energy Technology Data Exchange (ETDEWEB)

    Tesfa, Sintayehu, E-mail: sint_tesfa@yahoo.com [Max Planck Institute for the Physics of Complex Systems, Noethnitzer Street 38, 01187 Dresden (Germany); Physics Department, Dilla University, PO Box 419, Dilla (Ethiopia)

    2011-10-15

    A detailed analysis of the time evolution of the two-mode squeezing, entanglement and intensity of the cavity radiation of a two-photon correlated emission laser initially seeded with a thermal light is presented. The dependences of the degree of two-mode squeezing and entanglement on the intensity of the thermal light and time are found to have a more or less similar nature, although the actual values differ, especially in the early stages of the process and when the atoms are initially prepared with nearly 50:50 probability to be in the upper and lower energy levels. Seeding the cavity degrades the nonclassical features significantly, particularly in the vicinity of t=0. It is also shown that the mean photon number in a wider time span has a dip when mode b is seeded but a peak when mode a is seeded. Moreover, it turns out that the effect of the seed light on the nonclassical features and intensity of the cavity radiation decreases significantly with time, an outcome essentially attributed to the pertinent emission-absorption mechanism. This can be taken as an encouraging aspect in the practical utilization of this model as a source of a bright entangled light.

  13. Chaotic inflation with metric and matter perturbations

    International Nuclear Information System (INIS)

    Feldman, H.A.; Brandenberger, R.H.

    1989-01-01

    A perturbative scheme to analyze the evolution of both metric and scalar field perturbations in an expanding universe is developed. The scheme is applied to study chaotic inflation with initial metric and scalar field perturbations present. It is shown that initial gravitational perturbations with wavelength smaller than the Hubble radius rapidly decay. The metric simultaneously picks up small perturbations determined by the matter inhomogeneities. Both are frozen in once the wavelength exceeds the Hubble radius. (orig.)

  14. Aging effect on step adjustments and stability control in visually perturbed gait initiation.

    Science.gov (United States)

    Sun, Ruopeng; Cui, Chuyi; Shea, John B

    2017-10-01

    Gait adaptability is essential for fall avoidance during locomotion. It requires the ability to rapidly inhibit original motor planning, select and execute alternative motor commands, while also maintaining the stability of locomotion. This study investigated the aging effect on gait adaptability and dynamic stability control during a visually perturbed gait initiation task. A novel approach was used such that the anticipatory postural adjustment (APA) during gait initiation were used to trigger the unpredictable relocation of a foot-size stepping target. Participants (10 young adults and 10 older adults) completed visually perturbed gait initiation in three adjustment timing conditions (early, intermediate, late; all extracted from the stereotypical APA pattern) and two adjustment direction conditions (medial, lateral). Stepping accuracy, foot rotation at landing, and Margin of Dynamic Stability (MDS) were analyzed and compared across test conditions and groups using a linear mixed model. Stepping accuracy decreased as a function of adjustment timing as well as stepping direction, with older subjects exhibited a significantly greater undershoot in foot placement to late lateral stepping. Late adjustment also elicited a reaching-like movement (i.e. foot rotation prior to landing in order to step on the target), regardless of stepping direction. MDS measures in the medial-lateral and anterior-posterior direction revealed both young and older adults exhibited reduced stability in the adjustment step and subsequent steps. However, young adults returned to stable gait faster than older adults. These findings could be useful for future study of screening deficits in gait adaptability and preventing falls. Copyright © 2017 Elsevier B.V. All rights reserved.

  15. A possible mechanism for the seed island formation

    International Nuclear Information System (INIS)

    Pustovitov, V.D.

    2005-01-01

    The evolution of neoclassical tearing modes (NTMs) is usually described by the generalized Rutherford equation allowing the mode growth from a finite level, which is referred to as seed island. It is generally accepted that the seed island is induced by some MHD event, but sometimes the NTMs start without visible triggers. Here we discuss a possible role of the error fields in producing the seeds. The analysis is based on Maxwell equations and Ohm's law for magnetic perturbation outside the plasma. The plasma enters the problem via boundary conditions. Its contribution is described by the decay/growth rate and the toroidal rotation frequency of perturbation. The model also assumes a resonant harmonic in the spectrum of the error field. It is shown that the resonant field amplification near the stability boundary of the mode may be a mechanism resulting in the 'spontaneous' formation of the seed island. In contrast to NTM seeding due to the sawteeth, fishbones, or ELMs, the considered mechanism needs some longer time. However, all the estimates give realistic values consistent with typical experimental conditions. (author)

  16. Seeded hot dark matter models with inflation

    Science.gov (United States)

    Gratsias, John; Scherrer, Robert J.; Steigman, Gary; Villumsen, Jens V.

    1993-01-01

    We examine massive neutrino (hot dark matter) models for large-scale structure in which the density perturbations are produced by randomly distributed relic seeds and by inflation. Power spectra, streaming velocities, and the Sachs-Wolfe quadrupole fluctuation are derived for this model. We find that the pure seeded hot dark matter model without inflation produces Sachs-Wolfe fluctuations far smaller than those seen by COBE. With the addition of inflationary perturbations, fluctuations consistent with COBE can be produced. The COBE results set the normalization of the inflationary component, which determines the large-scale (about 50/h Mpc) streaming velocities. The normalization of the seed power spectrum is a free parameter, which can be adjusted to obtain the desired fluctuations on small scales. The power spectra produced are very similar to those seen in mixed hot and cold dark matter models.

  17. Perturbations in the initial soil moisture conditions: Impacts on hydrologic simulation in a large river basin

    Science.gov (United States)

    Niroula, Sundar; Halder, Subhadeep; Ghosh, Subimal

    2018-06-01

    Real time hydrologic forecasting requires near accurate initial condition of soil moisture; however, continuous monitoring of soil moisture is not operational in many regions, such as, in Ganga basin, extended in Nepal, India and Bangladesh. Here, we examine the impacts of perturbation/error in the initial soil moisture conditions on simulated soil moisture and streamflow in Ganga basin and its propagation, during the summer monsoon season (June to September). This provides information regarding the required minimum duration of model simulation for attaining the model stability. We use the Variable Infiltration Capacity model for hydrological simulations after validation. Multiple hydrologic simulations are performed, each of 21 days, initialized on every 5th day of the monsoon season for deficit, surplus and normal monsoon years. Each of these simulations is performed with the initial soil moisture condition obtained from long term runs along with positive and negative perturbations. The time required for the convergence of initial errors is obtained for all the cases. We find a quick convergence for the year with high rainfall as well as for the wet spells within a season. We further find high spatial variations in the time required for convergence; the region with high precipitation such as Lower Ganga basin attains convergence at a faster rate. Furthermore, deeper soil layers need more time for convergence. Our analysis is the first attempt on understanding the sensitivity of hydrological simulations of Ganga basin on initial soil moisture conditions. The results obtained here may be useful in understanding the spin-up requirements for operational hydrologic forecasts.

  18. Evaluating cotton seed gland initiation by microscopy

    Science.gov (United States)

    Gossypol is a terpenoid aldehyde found in cotton (Gossypium hirsutum L.) glands and helps protect the seed from pests and pathogens. However, gossypol is toxic to many animals, so the seed is used mainly in cattle feed, as ruminants are tolerant to the effects of gossypol. In order to develop strat...

  19. Mix and instability growth seeded at the inner surface of CH-ablator implosions on the National Ignition Facility

    Science.gov (United States)

    Haan, S. W.; Celliers, P. M.; Collins, G. W.; Orth, C. D.; Clark, D. S.; Amendt, P.; Hammel, B. A.; Robey, H. F.; Huang, H.

    2014-10-01

    Mix and hydro instability growth are key issues in implosions of ignition targets on NIF. The implosions are designed so that the amplitude of perturbations is thought to be determined by initial seeds to the hydrodynamic instabilities, amplified by an instability growth factor. Experiments have indicated that growth factors can be calculated fairly well, but characterizing the initial seeds is an ongoing effort. Several threads of investigation this year have increased our understanding of growth seeded at the CH/DT interface. These include: more detailed characterization of the CH inner surface; possible other seeds, such as density irregularities either from fabrication defects or arising during the implosion; experiments on the Omega laser measuring velocity modulations on shock fronts shortly after breaking out from the CH, which can seed subsequent growth; and the possible significance of non-hydrodynamic effects such as plasma interpenetration or spall-like ejecta upon shock breakout. This presentation describes these developments, the relationships between them, and their implications for ignition target performance. Work performed under the auspices of the U.S. D.O.E. by Lawrence Livermore National Laboratory under Contract No. DE-AC52-07NA27344.

  20. Efficiency of alfalfa seed processing with different seed purity

    OpenAIRE

    Đokić, Dragoslav; Stanisavljević, Rade; Terzić, Dragan; Milenković, Jasmina; Radivojević, Gordana; Koprivica, Ranko; Štrbanović, Ratibor

    2015-01-01

    The work was carried out analysis of the impact of the initial purity of raw alfalfa seed on the resulting amount of processed seed in the processing. Alfalfa is very important perennial forage legume which is used for fodder and seed production. Alfalfa seed is possible to achieve high yields and very good financial effects. To obtain the seed material with good characteristics complex machines for cleaning and sorting seeds are used. In the processing center of the Institute for forage crop...

  1. On dark energy isocurvature perturbation

    International Nuclear Information System (INIS)

    Liu, Jie; Zhang, Xinmin; Li, Mingzhe

    2011-01-01

    Determining the equation of state of dark energy with astronomical observations is crucially important to understand the nature of dark energy. In performing a likelihood analysis of the data, especially of the cosmic microwave background and large scale structure data the dark energy perturbations have to be taken into account both for theoretical consistency and for numerical accuracy. Usually, one assumes in the global fitting analysis that the dark energy perturbations are adiabatic. In this paper, we study the dark energy isocurvature perturbation analytically and discuss its implications for the cosmic microwave background radiation and large scale structure. Furthermore, with the current astronomical observational data and by employing Markov Chain Monte Carlo method, we perform a global analysis of cosmological parameters assuming general initial conditions for the dark energy perturbations. The results show that the dark energy isocurvature perturbations are very weakly constrained and that purely adiabatic initial conditions are consistent with the data

  2. Odd-parity perturbations of the self-similar LTB spacetime

    Energy Technology Data Exchange (ETDEWEB)

    Duffy, Emily M; Nolan, Brien C, E-mail: emilymargaret.duffy27@mail.dcu.ie, E-mail: brien.nolan@dcu.ie [School of Mathematical Sciences, Dublin City University, Glasnevin, Dublin 9 (Ireland)

    2011-05-21

    We consider the behaviour of odd-parity perturbations of those self-similar LemaItre-Tolman-Bondi spacetimes which admit a naked singularity. We find that a perturbation which evolves from initially regular data remains finite on the Cauchy horizon. Finiteness is demonstrated by considering the behaviour of suitable energy norms of the perturbation (and pointwise values of these quantities) on natural spacelike hypersurfaces. This result holds for a general choice of initial data and initial data surface. Finally, we examine the perturbed Weyl scalars in order to provide a physical interpretation of our results. Taken on its own, this result does not support cosmic censorship; however, a full perturbation of this spacetime would include even-parity perturbations, so we cannot conclude that this spacetime is stable to all linear perturbations.

  3. Effect of a relative phase of waves constituting the initial perturbation and the wave interference on the dynamics of strong-shock-driven Richtmyer-Meshkov flows

    Science.gov (United States)

    Pandian, Arun; Stellingwerf, Robert F.; Abarzhi, Snezhana I.

    2017-07-01

    While it is a common wisdom that initial conditions influence the evolution of the Richtmyer-Meshkov instability (RMI), the research in this area is focused primarily on the effects of the wavelength and amplitude of the interface perturbation. The information has hitherto largely ignored the influences on RMI dynamics of the relative phase of waves constituting a multiwave initial perturbation and the interference of the perturbation waves. In this work we systematically study the influence of the relative phase and the interference of waves constituting a multiwave initial perturbation on a strong-shock-driven Richtmyer-Meshkov unstable interface separating ideal fluids with contrast densities. We apply group theory analysis and smoothed particle hydrodynamics numerical simulations. For verification and validation of the simulations, qualitative and quantitative comparisons are performed with rigorous zeroth-order, linear, and nonlinear theories as well as with gas dynamics experiments achieving good agreement. For a sample case of a two-wave (two-mode) initial perturbation we select the first-wave amplitude enabling the maximum initial growth rate of the RMI and we vary the second-wave amplitude from 1% to 100% of the first-wave amplitude. We also vary the relative phase of the first and second waves and consider the in-phase, the antiphase and the random-phase cases. We find that the relative phase and the interference of waves are important factors of RMI dynamics influencing qualitatively and quantitatively the symmetry, morphology, and growth rate of the Richtmyer-Meshkov unstable interface, as well as the order and disorder in strong-shock-driven RMI.

  4. The initial value problem for linearized gravitational perturbations of the Schwarzschild naked singularity

    Energy Technology Data Exchange (ETDEWEB)

    Dotti, Gustavo; Gleiser, Reinaldo J [Facultad de Matematica, AstronomIa y Fisica (FaMAF), Universidad Nacional de Cordoba, Ciudad Universitaria, 5000 Cordoba (Argentina)

    2009-11-07

    The coupled equations for the scalar modes of the linearized Einstein equations around Schwarzschild's spacetime were reduced by Zerilli to a (1+1) wave equation partial deriv{sup 2}PSI{sub z} /partial derivt{sup 2} +HPSI{sub z} =0, where H= -partial deriv{sup 2} /partial derivx{sup 2} + V(x) is the Zerilli 'Hamiltonian' and x is the tortoise radial coordinate. From its definition, for smooth metric perturbations the field PSI{sub z} is singular at r{sub s} = -6M/(l - 1)(l +2), with l being the mode harmonic number. The equation PSI{sub z} obeys is also singular, since V has a second-order pole at r{sub s}. This is irrelevant to the black hole exterior stability problem, where r > 2M > 0, and r{sub s} < 0, but it introduces a non-trivial problem in the naked singular case where M < 0, then r{sub s} > 0, and the singularity appears in the relevant range of r (0 < r < infinity). We solve this problem by developing a new approach to the evolution of the even mode, based on a new gauge invariant function, PSI-circumflex, that is a regular function of the metric perturbation for any value of M. The relation of PSI-circumflex to PSI{sub z} is provided by an intertwiner operator. The spatial pieces of the (1 + 1) wave equations that PSI-circumflex and PSI{sub z} obey are related as a supersymmetric pair of quantum Hamiltonians H and H-circumflex. For M < 0,H-circumflex has a regular potential and a unique self-adjoint extension in a domain D defined by a physically motivated boundary condition at r = 0. This allows us to address the issue of evolution of gravitational perturbations in this non-globally hyperbolic background. This formulation is used to complete the proof of the linear instability of the Schwarzschild naked singularity, by showing that a previously found unstable mode belongs to a complete basis of H-circumflex in D, and thus is excitable by generic initial data. This is further illustrated by numerically solving the linearized equations for

  5. Cumulants in perturbation expansions for non-equilibrium field theory

    International Nuclear Information System (INIS)

    Fauser, R.

    1995-11-01

    The formulation of perturbation expansions for a quantum field theory of strongly interacting systems in a general non-equilibrium state is discussed. Non-vanishing initial correlations are included in the formulation of the perturbation expansion in terms of cumulants. The cumulants are shown to be the suitable candidate for summing up the perturbation expansion. Also a linked-cluster theorem for the perturbation series with cumulants is presented. Finally a generating functional of the perturbation series with initial correlations is studied. We apply the methods to a simple model of a fermion-boson system. (orig.)

  6. Initial performance of corn in response to treatment of seeds with humic acids isolated from bokashi

    Directory of Open Access Journals (Sweden)

    Marihus Altoé Baldotto

    2016-02-01

    Full Text Available ABSTRACT The humified organic matter presents bioactivity similar to the auxinic effect. As bokashi is produced by a special process of humification, information is needed about the bioactive potential of its humic acids. The objective of this work was studying the initial performance of corn-indicator plants in response to the application of different concentrations of humic acids isolated from bokashi. The corn seeds were treated for 16 hours with solutions containing 0, 10, 20, 30, 40 and 80 mmol L-1 of C in the form of humic acids. Then, the seeds were planted in pots of 1 dm3 containing corrected and fertilized soil, in greenhouse. Growth characteristics of shoot and root systems were evaluated. The results showed that the humic acids extracted from bokashi had positive effects on the initial performance of corn.

  7. Multimode seeded Richtmyer-Meshkov mixing in a convergent, compressible, miscible plasma system

    International Nuclear Information System (INIS)

    Lanier, N.E.; Barnes, Cris W.; Batha, S.H.; Day, R.D.; Magelssen, G.R.; Scott, J.M.; Dunne, A.M.; Parker, K.W.; Rothman, S.D.

    2003-01-01

    Richtmyer-Meshkov (RM) mixing seeded by multimode initial surface perturbations in a convergent, compressible, miscible plasma system is measured on the OMEGA [T. R. Boehly et al., Opt. Commun. 133, 495 (1997)] laser system. A strong shock (Mach 12-20), created by 50 laser beams, is used to accelerate impulsively a thin aluminum shell into a lower density foam. As the system converges, both interfaces of the aluminum are RM unstable and undergo mixing. Standard x-ray radiographic techniques are employed to survey accurately the zero-order hydrodynamics, the average radius and overall width, of the marker. LASNEX [G. B. Zimmerman et al., Comments on Plasma Physics 2, 51 (1975)] simulations are consistent with the zero-order behavior of initially smooth markers. In experiments with smooth aluminum markers, the measured marker width shortly after shock passage behaves incompressibly and thickens due to Bell-Plesset effects. At high convergence (>4), the marker begins to compress as the rebounding shock passes back through the marker. When an initial multimode perturbation is introduced to the outer surface of the marker, the measured marker width is observed to increase by 10-15 μm, and is substantially smaller than as-shot simulations using RAGE [R. M. Baltrusaitis et al., Phys. Fluids 8, 2471 (1996)] would predict

  8. Viscous modes, isocurvature perturbations and CMB initial conditions

    CERN Document Server

    Giovannini, Massimo

    2015-01-01

    When the predecoupling plasma is thermodinamically reversible its fluctuations are classified in terms of the adiabatic and entropic modes. A different category of physical solutions, so far unexplored, arises when the inhomogeneities of the viscosity coefficients induce computable curvature perturbations. The viscous modes are explicitly illustrated and compared with the conventional isocurvature solutions.

  9. The theory of singular perturbations

    CERN Document Server

    De Jager, E M

    1996-01-01

    The subject of this textbook is the mathematical theory of singular perturbations, which despite its respectable history is still in a state of vigorous development. Singular perturbations of cumulative and of boundary layer type are presented. Attention has been given to composite expansions of solutions of initial and boundary value problems for ordinary and partial differential equations, linear as well as quasilinear; also turning points are discussed. The main emphasis lies on several methods of approximation for solutions of singularly perturbed differential equations and on the mathemat

  10. Difference scheme for a singularly perturbed parabolic convection-diffusion equation in the presence of perturbations

    Science.gov (United States)

    Shishkin, G. I.

    2015-11-01

    An initial-boundary value problem is considered for a singularly perturbed parabolic convection-diffusion equation with a perturbation parameter ɛ (ɛ ∈ (0, 1]) multiplying the highest order derivative. The stability of a standard difference scheme based on monotone approximations of the problem on a uniform mesh is analyzed, and the behavior of discrete solutions in the presence of perturbations is examined. The scheme does not converge ɛ-uniformly in the maximum norm as the number of its grid nodes is increased. When the solution of the difference scheme converges, which occurs if N -1 ≪ ɛ and N -1 0 ≪ 1, where N and N 0 are the numbers of grid intervals in x and t, respectively, the scheme is not ɛ-uniformly well conditioned or stable to data perturbations in the grid problem and to computer perturbations. For the standard difference scheme in the presence of data perturbations in the grid problem and/or computer perturbations, conditions on the "parameters" of the difference scheme and of the computer (namely, on ɛ, N, N 0, admissible data perturbations in the grid problem, and admissible computer perturbations) are obtained that ensure the convergence of the perturbed solutions. Additionally, the conditions are obtained under which the perturbed numerical solution has the same order of convergence as the solution of the unperturbed standard difference scheme.

  11. Root-cause Investigation for No Setback Initiation at Liquid Zone Control Unit Perturbation in CANDU6 Reactor

    Energy Technology Data Exchange (ETDEWEB)

    Park, Donghwan; Kim, Youngae; Kim, Sungmin [KHNP Central Research Institute, Daejeon (Korea, Republic of)

    2016-10-15

    Liquid zone control system (LZCS) is one of the indigenous systems in CANDU type reactor for reactor reactivity control. The LZCS is filled with light water and used to provide a continuous fine control of the reactivity and the reactor power level. This system is also designed to accomplish spatial control of the power distribution, automatically, which prevents xenon induced power oscillations. As the tilt control term is phased out, it is replaced by a level control term, which tends to drive the individual zone levels towards the average level of all the zones. Most of CANDU reactors have been experienced these events. Generally setback or stepback conditions are on when variables of spatial control off, high zone power, etc. are reached to the initiating conditions before ROP trip. But the condition of setback or stepback is not initiated before ROP trip sometime. In this study the root-causes for this event are investigated, and the impact assessment is performed by physics computational modeling. To investigate the root-cause of ROP trip before initiating setback at abnormal operating condition, some LZC perturbation models were simulated and investigated the neutron flux readings of zone detector and ROP detector. Two root-causes were founded. The first, flux variation by water level change is more gradual than other zones due to design characteristics in zone 03. The second, ROP detector (SDS no. 2 3G) in the near zone 03 is very sensitive below 40% of water level due to ROP detector installed position. Even though setback is initiated earlier than ROP trip in case of zone 03 perturbation, ROP trip will be occurred because power decreasing rate is very slow(0.1%/sec) on setback condition.

  12. Mode coupling of Schwarzschild perturbations: Ringdown frequencies

    International Nuclear Information System (INIS)

    Pazos, Enrique; Brizuela, David; Martin-Garcia, Jose M.; Tiglio, Manuel

    2010-01-01

    Within linearized perturbation theory, black holes decay to their final stationary state through the well-known spectrum of quasinormal modes. Here we numerically study whether nonlinearities change this picture. For that purpose we study the ringdown frequencies of gauge-invariant second-order gravitational perturbations induced by self-coupling of linearized perturbations of Schwarzschild black holes. We do so through high-accuracy simulations in the time domain of first and second-order Regge-Wheeler-Zerilli type equations, for a variety of initial data sets. We consider first-order even-parity (l=2, m=±2) perturbations and odd-parity (l=2, m=0) ones, and all the multipoles that they generate through self-coupling. For all of them and all the initial data sets considered we find that--in contrast to previous predictions in the literature--the numerical decay frequencies of second-order perturbations are the same ones of linearized theory, and we explain the observed behavior. This would indicate, in particular, that when modeling or searching for ringdown gravitational waves, appropriately including the standard quasinormal modes already takes into account nonlinear effects.

  13. Spectrum of perturbations arising in a nonsingular model of the Universe with the initial de Sitter stage and the anisotropy of the relic radiation

    International Nuclear Information System (INIS)

    Starobinskij, A.A.

    1983-01-01

    Spectrum of primary adiabatic perturbations and gravitational waves formed in the proposed earlier by the author nonsingular cosmological model with the initial quantum de Sitter stage generated by gravitational vacuum polarization is calculated. The spectrum of gravitational waves appears to be flat, the spectrum of adiabatic perturbations is close to the flat one. The large-scale anisotropy of the temperature T of the relic electromagnetic radiation due to these fluctuations is found. It is shown that the most promising way to detect the anisotropy in the case of a flat perturbation spectrum is the investigation of correlations of ΔT/T at the angles of 5 deg - 10 deg

  14. Effects of Initial Seeding Density and Fluid Perfusion Rate on Formation of Tissue-Engineered Bone

    OpenAIRE

    GRAYSON, WARREN L.; BHUMIRATANA, SARINDR; CANNIZZARO, CHRISTOPHER; CHAO, P.-H. GRACE; LENNON, DONALD P.; CAPLAN, ARNOLD I.; VUNJAK-NOVAKOVIC, GORDANA

    2008-01-01

    We describe a novel bioreactor system for tissue engineering of bone that enables cultivation of up to six tissue constructs simultaneously, with direct perfusion and imaging capability. The bioreactor was used to investigate the relative effects of initial seeding density and medium perfusion rate on the growth and osteogenic differentiation patterns of bone marrow–derived human mesenchymal stem cells (hMSCs) cultured on three-dimensional scaffolds. Fully decellularized bovine trabecular bon...

  15. Preheating curvaton perturbations

    International Nuclear Information System (INIS)

    Bastero-Gil, M.; Di Clemente, V.; King, S.F.

    2005-01-01

    We discuss the potentially important role played by preheating in certain variants of the curvaton mechanism in which isocurvature perturbations of a D-flat (and F-flat) direction become converted to curvature perturbations during reheating. We discover that parametric resonance of the isocurvature components amplifies the superhorizon fluctuations by a significant amount. As an example of these effects we develop a particle physics motivated model which involves hybrid inflation with the waterfall field N being responsible for generating the μ term, the right-handed neutrino mass scale, and the Peccei-Quinn symmetry breaking scale. The role of the curvaton field can be played either by usual Higgs field, or the lightest right-handed sneutrino. Our new results show that it is possible to achieve the correct curvature perturbations for initial values of the curvaton fields of order the weak scale. In this model we show that the prediction for the spectral index of the final curvature perturbation only depends on the mass of the curvaton during inflation, where consistency with current observational data requires the ratio of this mass to the Hubble constant to be 0.3

  16. Myrmecochory and short-term seed fate in Rhamnus alaternus: Ant species and seed characteristics

    Science.gov (United States)

    Bas, J. M.; Oliveras, J.; Gómez, C.

    2009-05-01

    Benefits conferred on plants in ant-mediated seed dispersal mutualisms (myrmecochory) depend on the fate of transported seeds. We studied the effects of elaiosome presence, seed size and seed treatment (with and without passage through a bird's digestive tract) on short-term seed fate in Rhamnus alaternus. In our study, we define short-term seed, or initial, seed fate, as the location where ants release the seeds after ant contact with it. The elaiosomes had the most influence on short-term fate, i.e. whether or not seeds were transported to the nest. The workers usually transported big seeds more often than small ones, but small ants did not transport large seeds. Effect of seed size on transport depended on the ant species and on the treatment of the seed (manual extraction simulating a direct fall from the parent plant vs. bird deposition corresponding to preliminary primary dispersal). Probability of removal of elaiosome-bearing seeds to the nest by Aphaenogaster senilis increased with increasing seed weight.

  17. Seed rain dynamics following disturbance exclusion in a secondary tropical dry forest in Morelos, Mexico.

    Science.gov (United States)

    Ceccon, Eliane; Hernández, Patricia

    2009-01-01

    In most of the legally protected areas in Mexico local inhabitants use natural resources, such as fire wood or cattle grazing. These frequent but low-intensity disturbances have consequences at various levels of the tropical ecosystems and strongly impact forest structure and its regeneration capacity. Despite their importance, the effects of these perturbations in many aspects of tropical forest ecology and in the forest's capacity to recover after disturbance exclusion remain poorly understood. Understanding the impact of these processes on tropical forests is necessary for rehabilitating these forests and enhancing their productivity. In this study, we evaluate the impact of twelve years of exclusion (E) of cattle grazing and fire wood extraction in the composition and dynamics of seed rain, and compare this assessment to a similar analysis in an area where these perturbations continued (without exclusion, WE). We found a strong seasonality in seed rain (96% of seeds fell in the dry season) in both areas. There were no significant differences between E and WE sites in relation to overall seed density, species richness and diversity. However, the distribution along the year of seed species density was significantly different among the E and WE sites. The Jaccard's similarity index between E and WE sites was relatively low (0.57). Barochory was the most common dispersal mode observed among the 23 species in terms of seed species density (48%), followed by anemochory (39%) and zoochory (13%). In relation to seed density, anemochory was the most frequent dispersal mode (88%). Most species in the zone were categorized as small seeds (92%), and there were no significant differences in the distribution of seed size between E and WE. The spatial pattern of dispersal of the four species with the highest relative importance value index, in both areas, was aggregated. Twelve years of disturbance exclusion were not enough to fully restore the seed rain of the area; some

  18. Survival and death of seeds during liquid nitrogen storage: a case study on seeds with short lifespans.

    Science.gov (United States)

    Ballesteros, D; Pence, V C

    The low temperature of liquid nitrogen is assumed to stop ageing and preserve viability indefinitely, however there are few validating data sets. The use of seeds to test these assumptions is important because other cryopreserved systems lack quantitative measures of viability to allow comparisons among timed points. To evaluate survival of a collection of seeds with short lifespans stored 12-20 years in liquid nitrogen. Seeds from 11 species (26 accessions) were removed from cryostorage and evaluated for germination and normal growth. Germination of Plantago cordata and Betula spp. seeds did not decrease significantly during cryostorage. However, Populus deltoides and most Salix spp. accessions showed a significant decrease in germination, with further loss observed when P. deltoides seedlings were followed to the young plant stage. Seeds of initial low quality showed greater deterioration during cryostorage. Cryostorage maintained viability of Salix and Populus seeds longer than other temperatures. However, ageing was not completely stopped and seed longevity was shorter than that predicted for many other species. A high initial seed quality is important in order to obtain the maximum benefit of cryostorage.

  19. Understanding the unsteady aerodynamics of a revolving wing with pitching-flapping perturbations

    Science.gov (United States)

    Chen, Long; Wu, Jianghao; Zhou, Chao; Hsu, Shih-Jung; Eslam Panah, Azar; Cheng, Bo

    2017-11-01

    Revolving wings become less efficient for lift generation at low Reynolds numbers. Unlike flying insects using reciprocating revolving wings to exploit unsteady mechanisms for lift enhancement, an alternative that introduces unsteadiness through vertical flapping perturbation, is studied via experiments and simulations. Substantial drag reduction, linearly dependent on Strouhal number, is observed for a flapping-perturbed revolving wing at zero angle of attack (AoA), which can be explained by changes in the effective angle of attack and formation of reverse Karman vortex streets. When the AoA increases, flapping perturbations improve the maximum lift coefficient attainable by the revolving wing, with minor increases of drag or even minor drag reductions depending on Strouhal number and normalized flapping amplitude. When the pitching perturbations are further introduced, more substantial drag reduction and lift enhancement can be achieved in zero and positive AoAs, respectively. As the flapping-perturbed wings are less efficient compared with revolving wings in terms of power loading, the pitching-flapping perturbations can achieve a higher power loading at 20°AoA and thus have potential applications in micro air vehicle designs. This research was supported by NSF, DURIP, NSFC and Penn State Multi-Campus SEED Grant.

  20. Base case and perturbation scenarios

    Energy Technology Data Exchange (ETDEWEB)

    Edmunds, T

    1998-10-01

    This report describes fourteen energy factors that could affect electricity markets in the future (demand, process, source mix, etc.). These fourteen factors are believed to have the most influence on the State's energy environment. A base case, or most probable, characterization is given for each of these fourteen factors over a twenty year time horizon. The base case characterization is derived from quantitative and qualitative information provided by State of California government agencies, where possible. Federal government databases are nsed where needed to supplement the California data. It is envisioned that a initial selection of issue areas will be based upon an evaluation of them under base case conditions. For most of the fourteen factors, the report identities possible perturbations from base case values or assumptions that may be used to construct additional scenarios. Only those perturbations that are plausible and would have a significant effect on energy markets are included in the table. The fourteen factors and potential perturbations of the factors are listed in Table 1.1. These perturbations can be combined to generate internally consist.ent. combinations of perturbations relative to the base case. For example, a low natural gas price perturbation should be combined with a high natural gas demand perturbation. The factor perturbations are based upon alternative quantitative forecasts provided by other institutions (the Department of Energy - Energy Information Administration in some cases), changes in assumptions that drive the quantitative forecasts, or changes in assumptions about the structure of the California energy markets. The perturbations are intended to be used for a qualitative reexamination of issue areas after an initial evaluation under the base case. The perturbation information would be used as a "tiebreaker;" to make decisions regarding those issue areas that were marginally accepted or rejected under the base case. Hf a

  1. Initial conditions for chaotic inflation

    International Nuclear Information System (INIS)

    Brandenberger, R.; Kung, J.; Feldman, H.

    1991-01-01

    In contrast to many other inflationary Universe models, chaotic inflation does not depend on fine tuning initial conditions. Within the context of linear perturbation theory, it is shown that chaotic inflation is stable towards both metric and matter perturbations. Neglecting gravitational perturbations, it is shown that chaotic inflation is an attractor in initial condition space. (orig.)

  2. Monosynaptic Stretch Reflex Fails to Explain the Initial Postural Response to Sudden Lateral Perturbations

    Directory of Open Access Journals (Sweden)

    Andreas Mühlbeier

    2017-06-01

    Full Text Available Postural reflexes are essential for locomotion and postural stability, and may play an important role in the etiology of chronic back pain. It has recently been theoretically predicted, and with the help of unilateral perturbations of the trunk experimentally confirmed that the sensorimotor control must lower the reflex amplitude for increasing reflex delays to maintain spinal stability. The underlying neuromuscular mechanism for the compensation of postural perturbations, however, is not yet fully understood. In this study, we applied unilateral and bilateral sudden external perturbations to the trunk of healthy subjects and measured the muscular activity and the movement onset of the trunk. We found that the onset of the trunk muscle activity is prior to, or coincident with, the onset of the trunk movement. Additionally, the results of our experiments imply that the muscular response mechanism integrates distant sensory information from both sides of the body. These findings rule out a simple monosynaptic stretch reflex in favor of a more complex polysynaptic postural reflex mechanism to compensate postural perturbations. Moreover, the previously predicted negative correlation between reflex delay and reflex gain was also confirmed for bilateral perturbations.

  3. The spectrum of density perturbations in an expanding universe

    Science.gov (United States)

    Silk, J.

    1974-01-01

    The basic dynamic equations that govern the evolution of perturbations in a Friedmann-Lemaitre universe are derived. General solutions describing the evolution of adiabatic perturbations in the density of matter are obtained, and the choice of the appropriate initial conditions is examined. The various perturbation modes are compared, and the effects of decoupling on the perturbation spectrum are studied. The scheme used to follow the evolution of density perturbations through decoupling is based on an extension of the Eddington approximation to the radiative transfer equation, and is strictly valid in both optically thick and thin limits.

  4. Stability in and correlation between factors influencing genetic quality of seed lots in seed orchard of Pinus tabuliformis Carr. over a 12-year span.

    Directory of Open Access Journals (Sweden)

    Wei Li

    Full Text Available Coniferous seed orchards require a long period from initial seed harvest to stable seed production. Differential reproductive success and asynchrony are among the main factors for orchard crops year-to-year variation in terms of parental gametic contribution and ultimately the genetic gain. It is fundamental in both making predictions about the genetic composition of the seed crop and decisions about orchard roguing and improved seed orchard establishment. In this paper, a primary Chinese pine seed orchard with 49 clones is investigated for stability, variation and correlation analysis of factors which influence genetic quality of the seed lots from initial seed harvest to the stable seed production over a 12 years span. Results indicated that the reproductive synchrony index of pollen shedding has shown to be higher than that of the strobili receptivity, and both can be drastically influenced by the ambient climate factors. Reproductive synchrony index of the clones has certain relative stability and it could be used as an indication of the seed orchard status during maturity stage; clones in the studied orchard have shown extreme differences in terms of the gametic and genetic contribution to the seed crop at the orchard's early production phase specifically when they severe as either female or male parents. Those differences are closely related to clonal sex tendency at the time of orchard's initial reproduction. Clonal gamete contribution as male and female parent often has a negative correlation. Clone utilization as pollen, seed or both pollen and seed donors should consider the role it would play in the seed crop; due to numerous factors influencing on the mating system in seed orchards, clonal genetic contribution as male parent is uncertain, and it has major influence on the genetic composition in the seed orchard during the initial reproductive and seed production phase.

  5. Oxyradical accumulation and rapid deterioration of soybean seeds due to field weathering.

    Science.gov (United States)

    Yadav, Sanjeev; Bhatia, V S; Guruprasad, K N

    2006-02-01

    The effect of field weathering on oxyradical accumulation and subsequent changes were studied in the seeds of soybean [Glycine max (L.) Merr.] cv. JS 71-05. Electron spin resonance (ESR) quantification of oxyradical revealed that field weathering plays an important role in acceleration of their accumulation. One week of weathering increased the accumulation of oxyradicals to almost 2-fold and triggered the deteriorative cascade, by enhancing the lipid peroxidation and membrane perturbation, leading to cell death in seed tissues and poor germinability and vigour of soybean seeds. Thus, the weather conditions at the time of physiological maturity to harvesting of crop are very crucial and the field weathering plays a critical role for the maintenance of seed quality.

  6. Challenges of establishing big sgebrush (Artemisia tridentata) in rangeland restoration: effects of herbicide, mowing, whole-community seeding, and sagebrush seed sources

    Science.gov (United States)

    Brabec, Martha M.; Germino, Matthew J.; Shinneman, Douglas J.; Pilliod, David S.; McIlroy, Susan K.; Arkle, Robert S.

    2015-01-01

    The loss of big sagebrush (Artemisia tridentata Nutt.) on sites disturbed by fire has motivated restoration seeding and planting efforts. However, the resulting sagebrush establishment is often lower than desired, especially in dry areas. Sagebrush establishment may be increased by addressing factors such as seed source and condition or management of the plant community. We assessed initial establishment of seeded sagebrush and four populations of small outplants (from different geographies, climates, and cytotypes) and small sagebrush outplants in an early seral community where mowing, herbicide, and seeding of other native plants had been experimentally applied. No emergence of seeded sagebrush was detected. Mowing the site before planting seedlings led to greater initial survival probabilities for sagebrush outplants, except where seeding also occurred, and these effects were related to corresponding changes in bare soil exposure. Initial survival probabilities were > 30% greater for the local population of big sagebrush relative to populations imported to the site from typical seed transfer distances of ~320–800 km. Overcoming the high first-year mortality of outplanted or seeded sagebrush is one of the most challenging aspects of postfire restoration and rehabilitation, and further evaluation of the impacts of herb treatments and sagebrush seed sources across different site types and years is needed.

  7. The role of seed coat phenolics on water uptake and early protein synthesis during germination of dimorphic seeds of halopyrum mucronatum (L.) staph

    International Nuclear Information System (INIS)

    Siddiqui, Z. S.; Khan, M.A.

    2010-01-01

    Role of seed coat phenolics on water uptake and early protein synthesis of Halopyrum mucronatum dimorphic seeds during germination were tested. Scanning electron micrographs (SEM) showed seed texture with differential deposition of secondary metabolites in both morphs. Ability of both seed morphs to retain secondary deposition was dependent on exposure to either saline or non-saline conditions. More phenols leached from the brown seed during the initial hours of soaking when compared to black seeds. Water uptake pattern was slightly different in both seed type particularly during initial hours when imbibition in black seeds showed little water uptake while in brown seeds absorption was quick in the first hour under both saline and non saline condition. Change in total protein was somewhat similar in both seeds morphs showing early increase (4 and 8 h), reaching to the maximum (12 h) and decreasing (24 and 48 h) afterward. The results are discussed in relation to seed coat phenolics, water uptake and early protein synthesis during germination. (author)

  8. Instability growth seeded by ablator material inhomogeneity in indirect drive implosions on the National Ignition Facility

    Science.gov (United States)

    Haan, Steven; Ali, S. J.; Baxamusa, S. H.; Celliers, P. M.; Clark, D. S.; Kritcher, A. L.; Nikroo, A.; Stadermann, M.; Biener, J.; Wallace, R.; Smalyuk, V.; Robey, H.; Weber, C. R.; Huang, H.; Reynolds, H.; Carlson, L.; Rice, N.; Kline, J. L.; Simakov, A. N.; Yi, S. A.

    2017-10-01

    NIF indirect drive ablators (CH, Be, and high density carbon HDC) show hydrodynamic irregularity beyond that expected from surface features. Characterizing these seeds and estimating their growth is important in projecting performance. The resulting modulations can be measured in x-ray backlit implosions on NIF called Hydro Growth Radiography, and on Omega with 2D velocimetry. This presentation summarizes the experiments for the three ablators, along with simulations thereof and projections of the significance for NIF. For CH, dominant seeds are photo-induced oxidation, which might be mitigated with alumina coating. For Be, perturbations result from Ar and O contamination. For HDC, perturbations are seeded by shock propagation around melt, depend on shock strength, and may constrain the adiabat of future HDC implosions. Work performed under the auspices of the U.S. D.O.E. by Lawrence Livermore National Laboratory under Contract No. DE-AC52-07NA27344.

  9. ECOPHYSIOLOGICAL ANALYSIS OF GENIPA AMERICANA L. SEEDS IN AN INDUCED SOIL SEED BANK

    Directory of Open Access Journals (Sweden)

    Francesca Salla

    2016-03-01

    Full Text Available This work studied the behavior of G. americana L. (Rubiaceae seeds in an induced soil seed bank. This study was conducted in Lavras-MG in a seasonal semideciduous forest of the Federal University of Lavras. Seeds collected in the area were cleaned and analyzed (water content, viability and desiccation tolerance. Soil banks were installed in two distinct areas (top of hill and riparian forest located in the understory of the forest. Seeds were placed in nylon nets and covered with a thin litter layer that was previously removed for this purpose. Monthly assessment of germination, seedling emergence, seed and soil water content, and the characterization of the initial seedling growth was performed. It was observed that G. americana seeds forms a transitory seed bank, with maintenance of its viability until the fourth month after disposal in natural environment. In general, the seed bank located in the riparian forest area showed the best potential for seedling establishment in a natural environment, which supports the ecological behavior of this species.

  10. Gibbs perturbations of a two-dimensional gauge field

    International Nuclear Information System (INIS)

    Petrova, E.N.

    1981-01-01

    Small Gibbs perturbations of random fields have been investigated up to now for a few initial fields only. Among them there are independent fields, Gaussian fields and some others. The possibility for the investigation of Gibbs modifications of a random field depends essentially on the existence of good estimates for semiinvariants of this field. This is the reason why the class of random fields for which the investigation of Gibbs perturbations with arbitrary potential of bounded support is possible is rather small. The author takes as initial a well-known model: a two-dimensional gauge field. (Auth.)

  11. Seed reserve utilization and hydrolytic enzyme activities in germinating seeds of sweet corn

    International Nuclear Information System (INIS)

    Cheng, X.; Xiong, F.; Wang, C.; He, S.; Zhou, Y.

    2018-01-01

    In this study, two sh2 sweet corn cultivars (i.e., the initial seed dry weight for FT018 and TB010 was 0.16+-0.02 g/grain and 0.09+-0.01 g/grain, respectively) were used to determine the physiological characteristics of seed reserve utilization in germination. The data implied that the weight of mobilized seed reserve (WMSR) and seed reserve utilization efficiency (SRUE) increased with seed germination. FT018 exhibited higher SRUE than TB010 due to its sufficient energy production for growth. Sugar (sucrose and fructose) contents were at different levels in the germinating seed of sh2 sweet corn. The protein content and number of protein species were highest in the early stage of germination. Enzyme activity in the germinating seed indicated that enzymes for starch and sugar hydrolysis were important and that enzyme activities significantly differed at each germination stage and between the cultivars under dark conditions. Succinate dehydrogenase, sucrose synthase, and glucose-6-phosphate dehydrogenase accumulated in the late germination stage. Thus, appropriate efforts should be focused on improving the seed reserve utilization in sweet corn by identifying the physiological mechanism of germinating seed. (author)

  12. Oil seed marketing prospects

    International Nuclear Information System (INIS)

    Ceroni, G.

    1992-01-01

    With its 100 million tonnes annual production, the American continent is by far the world's biggest producer of oil seed, followed by Asia - 52 million, and Europe - 27 million tonnes. The Italian and European Communities have the farming capacity to double their production, but international agreements currently prohibit such initiatives. After first providing a panorama of the world oil seed market, this paper discusses new reforms in European Communities internal agricultural policies which currently limit production. These reforms, intended to encourage the production of oil seed for use as an ecological automotive fuel alternative, call for an obligatory set-aside of 15% of producing farm-land in exchange for the compensatory removal of oil seed production limits

  13. Mechanism of fluridone-induced seed germination of cistanche tubulosa

    International Nuclear Information System (INIS)

    Chen, Q.L.; Tu, P.

    2016-01-01

    Our previous study disclosed that fluridone, a synthesis inhibitor of abscisic acid (ABA), could stimulate seed germination in the holoparasitic plant Cistanche tubulosa . Nonetheless, the underlying mechanisms have not been thoroughly elucidated. In the present study, an attempt was made to reveal the mechanism of fluridone breaking seed dormancy in C. tubulosa and to determine the contribution of hormones in this process. The ABA level in seeds initially decreased following fluridone treatment and was subsequently maintained at a concentration of 31 ng g/sup -1/ DW (dry weight) three days later. The contents of gibberellins (GAs) initially in creased and subsequently were maintained at a level of 40 ng g-1 DW after ten days. However, the increment of seed germination induced by fluridone was inhibited after the introduction of exogenous ABA or paclobutrazol (a synthesis inhibitor of GAs). Furthermore, inhibition from paclobutrazol was reversed by an additional treatment with exogenous GA3. When the ratio of endogenous GAs to ABA reached 4:3, C. tubulosa seeds initiated germination. By contrast, although the ratio of endogenous GAs to ABA content reached 2:1 by cold stratification, C. tubulosa seeds could not germinate unless exogenous GA3 was added. In summary, our current study revealed that (i) GAs and ABA play key roles for the seed germination of C. tubulosa , (ii) fluridone inhibited ABA biosynthesis but increased the concentration of GAs in seeds, and (iii) fluridone might initiate other processes associated with germination. (author)

  14. Divergence of perturbation theory in large scale structures

    Science.gov (United States)

    Pajer, Enrico; van der Woude, Drian

    2018-05-01

    We make progress towards an analytical understanding of the regime of validity of perturbation theory for large scale structures and the nature of some non-perturbative corrections. We restrict ourselves to 1D gravitational collapse, for which exact solutions before shell crossing are known. We review the convergence of perturbation theory for the power spectrum, recently proven by McQuinn and White [1], and extend it to non-Gaussian initial conditions and the bispectrum. In contrast, we prove that perturbation theory diverges for the real space two-point correlation function and for the probability density function (PDF) of the density averaged in cells and all the cumulants derived from it. We attribute these divergences to the statistical averaging intrinsic to cosmological observables, which, even on very large and "perturbative" scales, gives non-vanishing weight to all extreme fluctuations. Finally, we discuss some general properties of non-perturbative effects in real space and Fourier space.

  15. Dynamics of entropy perturbations in assisted dark energy with mixed kinetic terms

    International Nuclear Information System (INIS)

    Karwan, Khamphee

    2011-01-01

    We study dynamics of entropy perturbations in the two-field assisted dark energy model. Based on the scenario of assisted dark energy, in which one scalar field is subdominant compared with the other in the early epoch, we show that the entropy perturbations in this two-field system tend to be constant on large scales in the early epoch and hence survive until the present era for a generic evolution of both fields during the radiation and matter eras. This behaviour of the entropy perturbations is preserved even when the fields are coupled via kinetic interaction. Since, for assisted dark energy, the subdominant field in the early epoch becomes dominant at late time, the entropy perturbations can significantly influence the dynamics of density perturbations in the universe. Assuming correlations between the entropy and curvature perturbations, the entropy perturbations can enhance the integrated Sachs-Wolfe (ISW) effect if the signs of the contributions from entropy perturbations and curvature perturbations are opposite after the matter era, otherwise the ISW contribution is suppressed. For canonical scalar field the effect of entropy perturbations on ISW effect is small because the initial value of the entropy perturbations estimated during inflation cannot be sufficiently large. However, in the case of k-essence, the initial value of the entropy perturbations can be large enough to affect the ISW effect to leave a significant imprint on the CMB power spectrum

  16. Glioblastoma with spinal seeding

    International Nuclear Information System (INIS)

    Fakhrai, N.; Fazeny-Doerner, B.; Marosi, C.; Czech, T.; Diekmann, K.; Birner, P.; Hainfellner, J.A.; Prayer, D.

    2004-01-01

    Background: extracranial seeding of glioblastoma multiforme (GBM) is very rare and its development depends on several factors. This case report describes two patients suffering from GBM with spinal seeding. In both cases, the anatomic localization of the primary tumor close to the cerebrospinal fluid (CSF) was the main factor for spinal seeding. Case reports: two patients with GBM and spinal seeding are presented. After diagnosis of spinal seeding, both patients were highly symptomatic from their spinal lesions. Case 1 experienced severe pain requiring opiates, and case 2 had paresis of lower limbs as well as urinary retention/incontinence. Both patients were treated with spinal radiation therapy. Nevertheless, they died 3 months after diagnosis of spinal seeding. Results: in both patients the diagnosis of spinal seeding was made at the time of cranial recurrence. Both tumors showed close contact to the CSF initially. Even though the patients underwent intensive treatment, it was not possible to keep them in a symptom-free state. Conclusion: because of short survival periods, patients deserve optimal pain management and dedicated palliative care. (orig.)

  17. Glioblastoma with spinal seeding

    Energy Technology Data Exchange (ETDEWEB)

    Fakhrai, N.; Fazeny-Doerner, B.; Marosi, C. [Clinical Div. of Oncology, Dept. of Medicine I, Univ. of Vienna (Austria); Czech, T. [Dept. of Neurosurgery, Univ. of Vienna (Austria); Diekmann, K. [Dept. of Radiooncology, Univ. of Vienna (Austria); Birner, P.; Hainfellner, J.A. [Clinical Inst. for Neurology, Univ. of Vienna (Austria); Prayer, D. [Dept. of Neuroradiology, Univ. of Vienna (Austria)

    2004-07-01

    Background: extracranial seeding of glioblastoma multiforme (GBM) is very rare and its development depends on several factors. This case report describes two patients suffering from GBM with spinal seeding. In both cases, the anatomic localization of the primary tumor close to the cerebrospinal fluid (CSF) was the main factor for spinal seeding. Case reports: two patients with GBM and spinal seeding are presented. After diagnosis of spinal seeding, both patients were highly symptomatic from their spinal lesions. Case 1 experienced severe pain requiring opiates, and case 2 had paresis of lower limbs as well as urinary retention/incontinence. Both patients were treated with spinal radiation therapy. Nevertheless, they died 3 months after diagnosis of spinal seeding. Results: in both patients the diagnosis of spinal seeding was made at the time of cranial recurrence. Both tumors showed close contact to the CSF initially. Even though the patients underwent intensive treatment, it was not possible to keep them in a symptom-free state. Conclusion: because of short survival periods, patients deserve optimal pain management and dedicated palliative care. (orig.)

  18. Profiles of an initially perturbed electron beam

    International Nuclear Information System (INIS)

    Abdelsalam, F.W.

    1991-01-01

    This paper discusses the solutions for the profiles of an electron beam which is launched into a constant magnetic field with an initial boundary slope and injected with a radius which is greater or less than the cathode radius. It has been found that the outermost electron traces sine waves and executes limited excursions when the initial boundary slope corresponds to angles up to 1 degree, no matter whether the initial radius is 0.90 or 1.10 times the radius of the cathode. For initial inclination angles close to 2 degrees, the beam boundary does not preserve a sinusoidal shape, this statement holds true for focusing magnetic flux densities varying from 200x10 -4 to 700x10 -4 weber per square meter

  19. Translocation of the neonicotinoid seed treatment clothianidin in maize.

    Science.gov (United States)

    Alford, Adam; Krupke, Christian H

    2017-01-01

    Neonicotinoid seed treatments, typically clothianidin or thiamethoxam, are routinely applied to >80% of maize (corn) seed grown in North America where they are marketed as a targeted pesticide delivery system. Despite this widespread use, the amount of compound translocated into plant tissue from the initial seed treatment to provide protection has not been reported. Our two year field study compared concentrations of clothianidin seed treatments in maize to that of maize without neonicotinoid seed treatments and found neonicotinoids present in root tissues up to 34 days post planting. Plant-bound clothianidin concentrations followed an exponential decay pattern with initially high values followed by a rapid decrease within the first ~20 days post planting. A maximum of 1.34% of the initial seed treatment was successfully recovered from plant tissues in both study years and a maximum of 0.26% was recovered from root tissue. Our findings show neonicotinoid seed treatments may provide protection from some early season secondary maize pests. However, the proportion of the neonicotinoid seed treatment clothianidin translocated into plant tissues throughout the growing season is low overall and this observation may provide a mechanism to explain reports of inconsistent efficacy of this pest management approach and increasing detections of environmental neonicotinoids.

  20. Translocation of the neonicotinoid seed treatment clothianidin in maize.

    Directory of Open Access Journals (Sweden)

    Adam Alford

    Full Text Available Neonicotinoid seed treatments, typically clothianidin or thiamethoxam, are routinely applied to >80% of maize (corn seed grown in North America where they are marketed as a targeted pesticide delivery system. Despite this widespread use, the amount of compound translocated into plant tissue from the initial seed treatment to provide protection has not been reported. Our two year field study compared concentrations of clothianidin seed treatments in maize to that of maize without neonicotinoid seed treatments and found neonicotinoids present in root tissues up to 34 days post planting. Plant-bound clothianidin concentrations followed an exponential decay pattern with initially high values followed by a rapid decrease within the first ~20 days post planting. A maximum of 1.34% of the initial seed treatment was successfully recovered from plant tissues in both study years and a maximum of 0.26% was recovered from root tissue. Our findings show neonicotinoid seed treatments may provide protection from some early season secondary maize pests. However, the proportion of the neonicotinoid seed treatment clothianidin translocated into plant tissues throughout the growing season is low overall and this observation may provide a mechanism to explain reports of inconsistent efficacy of this pest management approach and increasing detections of environmental neonicotinoids.

  1. Microgravity effects on different stages of higher plant life cycle and completion of the seed-to-seed cycle.

    Science.gov (United States)

    De Micco, V; De Pascale, S; Paradiso, R; Aronne, G

    2014-01-01

    Human inhabitation of Space requires the efficient realisation of crop cultivation in bioregenerative life-support systems (BLSS). It is well known that plants can grow under Space conditions; however, perturbations of many biological phenomena have been highlighted due to the effect of altered gravity and its possible interactions with other factors. The mechanisms priming plant responses to Space factors, as well as the consequences of such alterations on crop productivity, have not been completely elucidated. These perturbations can occur at different stages of plant life and are potentially responsible for failure of the completion of the seed-to-seed cycle. After brief consideration of the main constraints found in the most recent experiments aiming to produce seeds in Space, we focus on two developmental phases in which the plant life cycle can be interrupted more easily than in others also on Earth. The first regards seedling development and establishment; we discuss reasons for slow development at the seedling stage that often occurs under microgravity conditions and can reduce successful establishment. The second stage comprises gametogenesis and pollination; we focus on male gamete formation, also identifying potential constraints to subsequent fertilisation. We finally highlight how similar alterations at cytological level can not only be common to different processes occurring at different life stages, but can be primed by different stress factors; such alterations can be interpreted within the model of 'stress-induced morphogenic response' (SIMR). We conclude by suggesting that a systematic analysis of all growth and reproductive phases during the plant life cycle is needed to optimise resource use in plant-based BLSS. © 2013 German Botanical Society and The Royal Botanical Society of the Netherlands.

  2. Regulation of carotenoid and ABA accumulation during the development and germination of Nicotiana plumbaginifolia seeds.

    Science.gov (United States)

    Frey, Anne; Boutin, Jean-Pierre; Sotta, Bruno; Mercier, Raphaël; Marion-Poll, Annie

    2006-08-01

    Abscisic acid (ABA) is derived from epoxycarotenoid cleavage and regulates seed development and maturation. A detailed carotenoid analysis was undertaken to study the contribution of epoxycarotenoid synthesis to the regulation of ABA accumulation in Nicotiana plumbaginifolia developing seeds. Maximal accumulation of xanthophylls occurred at mid-development in wild type seeds, when total ABA levels also peaked. In contrast, in ABA-deficient mutants xanthophyll synthesis was delayed, in agreement with the retardation in seed maturation. Seed dormancy was restored in mutants impaired in the conversion of zeaxanthin into violaxanthin by zeaxanthin epoxidase (ZEP), by the introduction of the Arabidopsis AtZEP gene under the control of promoters inducing expression during later stages of seed development compared to wild type NpZEP, and in dry and imbibed seeds. Alterations in the timing and level of ZEP expression did not highly affect the temporal regulation of ABA accumulation in transgenic seeds, despite notable perturbations in xanthophyll accumulation. Therefore, major regulatory control of ABA accumulation might occur downstream of epoxycarotenoid synthesis.

  3. Application of functional analysis to perturbation theory of differential equations. [nonlinear perturbation of the harmonic oscillator

    Science.gov (United States)

    Bogdan, V. M.; Bond, V. B.

    1980-01-01

    The deviation of the solution of the differential equation y' = f(t, y), y(O) = y sub O from the solution of the perturbed system z' = f(t, z) + g(t, z), z(O) = z sub O was investigated for the case where f and g are continuous functions on I x R sup n into R sup n, where I = (o, a) or I = (o, infinity). These functions are assumed to satisfy the Lipschitz condition in the variable z. The space Lip(I) of all such functions with suitable norms forms a Banach space. By introducing a suitable norm in the space of continuous functions C(I), introducing the problem can be reduced to an equivalent problem in terminology of operators in such spaces. A theorem on existence and uniqueness of the solution is presented by means of Banach space technique. Norm estimates on the rate of growth of such solutions are found. As a consequence, estimates of deviation of a solution due to perturbation are obtained. Continuity of the solution on the initial data and on the perturbation is established. A nonlinear perturbation of the harmonic oscillator is considered a perturbation of equations of the restricted three body problem linearized at libration point.

  4. Production of quality/certified seed of fodder-crops

    International Nuclear Information System (INIS)

    Bhutta, A.R.; Hussain, A.

    2006-01-01

    Although, Pakistan has well developed Seed-production and certification Programme for major crops, but seed programme for fodder-crops is still not well organized. Availability of local certified seed, remained 250-350 mt for Berseem, Sorghum, maize, barley and oat. About 5000 to 9000 mt of seed has being imported during 2003-04 to 2005-06. Fodder Research Institute and jullundhur Seed Corporation have demonstrated a model of public/private partnership for initiation of certified seed of a few fodder crops. To produce quality seeds of fodder crops, various steps, procedures and prescribed standards have been given, which will help in production of quality seed of fodder crops in Pakistan. (author)

  5. Thermal Properties of Kerstingiella geocarpa Seeds as Influenced ...

    African Journals Online (AJOL)

    The specific heat capacity, thermal conductivity and thermal diffusivity of Kerstingiella geocarpa seeds were determined as a function of moisture content. The initial moisture content of the seeds determined using the ASAE standard test was 10.0 % (d.b). The specific heat capacity of Kerstingiella geocarpa seed increased ...

  6. Modeling Small-Amplitude Perturbations in Inertial Confinement Fusion Pellets

    Science.gov (United States)

    Zalesak, Steven; Metzler, N.; Velikovich, A. L.; Gardner, J. H.; Manheimer, W.

    2005-10-01

    Recent advances in inertial confinement fusion (ICF) technology serve to ensure that imploding laser-driven ICF pellets will spend a significantly larger portion of their time in what is regarded as the ``linear'' portion of their perturbation evolution, i.e., in the presence of small-amplitude but nonetheless evolving perturbations. Since the evolution of these linear perturbations collectively form the initial conditions for the subsequent nonlinear evolution of the pellet, which in turn determines the energy yield of the pellet, the accurate numerical modeling of these small-amplitude perturbations has taken on an increased importance. This modeling is difficult despite the expected linear evolution of the perturbations themselves, because these perturbations are embedded in a highly nonlinear, strongly-shocked, and highly complex flow field which in and of itself stresses numerical computation capabilities, and whose simulation often employs numerical techniques which were not designed with the proper treatment of small-amplitude perturbations in mind. In this paper we will review some of the techniques that we have recently found to be of use toward this end.

  7. Perturbative instabilities in Horava gravity

    International Nuclear Information System (INIS)

    Bogdanos, Charalampos; Saridakis, Emmanuel N

    2010-01-01

    We investigate the scalar and tensor perturbations in Horava gravity, with and without detailed balance, around a flat background. Once both types of perturbations are taken into account, it is revealed that the theory is plagued by ghost-like scalar instabilities in the range of parameters which would render it power-counting renormalizable, that cannot be overcome by simple tricks such as analytic continuation. Implementing a consistent flow between the UV and IR limits seems thus more challenging than initially presumed, regardless of whether the theory approaches general relativity at low energies or not. Even in the phenomenologically viable parameter space, the tensor sector leads to additional potential problems, such as fine-tunings and super-luminal propagation.

  8. Controlling chaos in low and high dimensional systems with periodic parametric perturbations

    International Nuclear Information System (INIS)

    Mirus, K.A.; Sprott, J.C.

    1998-06-01

    The effect of applying a periodic perturbation to an accessible parameter of various chaotic systems is examined. Numerical results indicate that perturbation frequencies near the natural frequencies of the unstable periodic orbits of the chaotic systems can result in limit cycles for relatively small perturbations. Such perturbations can also control or significantly reduce the dimension of high-dimensional systems. Initial application to the control of fluctuations in a prototypical magnetic fusion plasma device will be reviewed

  9. Volatile emission in dry seeds as a way to probe chemical reactions during initial asymptomatic deterioration.

    Science.gov (United States)

    Mira, Sara; Hill, Lisa M; González-Benito, M Elena; Ibáñez, Miguel Angel; Walters, Christina

    2016-03-01

    The nature and kinetics of reactions in dry seeds determines how long the seeds survive. We used gas chromatography to assay volatile organic compounds (VOCs) emitted from seeds of three unrelated species as a means to non-invasively probe chemical changes during very dry, dry, and humid storage (seeds were dried to 5.5, 33, and 75% relative humidity at room temperature). VOCs emitted from seeds stored in humid conditions reflected fermentation-type reactions, with methanol and ethanol being predominant in Lactuca sativa and Carum carvi, and acetaldehyde and acetone being predominant in Eruca vesicaria. Dried C. carvi seeds continued to emit fermentation-type products, although at slower rates than the seeds stored in humid conditions. In contrast, drying caused a switch in VOC emission in L. sativa and E. vesicaria seeds towards higher emission of pentane and hexanal, molecules considered to be byproducts from the peroxidation of polyunsaturated fatty acids. Longevity correlated best with the rate of fermentation-type reactions and appeared unrelated to the rate of lipid peroxidation. Emission of VOCs decreased when seed species were mixed together, indicating that seeds adsorbed VOCs. Adsorption of VOCs did not appear to damage seeds, as longevity was not affected in seed mixtures. Collectively, the study shows similarity among species in the types of reactions that occur in dry seeds, but high diversity in the substrates, and hence the byproducts, of the reactions. Moreover, the study suggests that the most abundant VOCs arise from degradation of storage reserves within seed cells, and that these reactions and their byproducts are not, in themselves, damaging. © The Author 2016. Published by Oxford University Press on behalf of the Society for Experimental Biology.

  10. Stimulation of lettuce seed germination by ethylene.

    Science.gov (United States)

    Abeles, F B; Lonski, J

    1969-02-01

    Ethylene increased the germination of freshly imbibed lettuce (Lactuca sativa L. var. Grand Rapids) seeds. Seeds receiving either red or far-red light or darkness all showed a positive response to the gas. However, ethylene was apparently without effect on dormant seeds, those which failed to germinate after an initial red or far-red treatment. Carbon dioxide, which often acts as a competitive inhibitor of ethylene, failed to clearly reverse ethylene-enhanced seed germination. While light doubled ethylene production from the lettuce seeds, its effect was not mediated by the phytochrome system since both red and far-red light had a similar effect.

  11. IMPORTANCE OF STORAGE CONDITIONS AND SEED TREATMENT FOR SUNFLOWER HYBRIDS SEEDS GERMINATION

    Directory of Open Access Journals (Sweden)

    Goran Krizmanić

    2014-12-01

    Full Text Available In this research we have determined germination energy and germination of seeds of sunflower hybrids ‘Luka’ and ‘Apolon’, at the beginning of storage and 6, 12 and 18 months after of storage period (2011-2012 in the floor concrete storage at two different air temperatures and humidity (S-1: air temperature 15-18°C and relative air humidity 65-70% as well as in climate chamber (S-2: air temperature 10-12°C and relative air humidity 60-65%, stored in four treatments (Control: processed-untreated seed; T-1: treated with A.I. metalaxyl-M; T-2: treated with A.I. metalaxyl-M + A.I. imidacloprid and T-3: treated with A.I. metalaxyl-M + A.I. clothianidin. Based on the obtained results we have determined that sunflower hybrid ‘Luka’, compared to hybrid ‘Apolon’, in the given storage conditions and with the same seed treatment has 5-8% higher germination energy and seed germination and that in climate chamber both hybrids have 5-7% higher germination energy. Seed treatment of both sunflower hybrids with A.I. imidacloprid maximally reduced initial germination energy and seed germination in all tested periods and conditions of storage. On the average, natural seed, after 18 months of storage did not have better seed quality compared to seed treated with A.I. metalaxyl-M while other treatments had more significant influence on reduction of germination energy and seed germination, 6-15%. On the average, compared to other variants, seeds treated with A.I. metalaxyl-M after 18 months of storage in both storage conditions had higher germination energy by 4-15%, and seed germination by 2-12%.

  12. Derivation and experimental demonstration of the perturbed reactivity method for the determination of subcriticality

    International Nuclear Information System (INIS)

    Kwok, K.S.; Bernard, J.A.; Lanning, D.D.

    1992-01-01

    The perturbed reactivity method is a general technique for the estimation of reactivity. It is particularly suited to the determination of a reactor's initial degree of subcriticality and was developed to facilitate the automated startup of both spacecraft and multi-modular reactors using model-based control laws. It entails perturbing a shutdown reactor by the insertion of reactivity at a known rate and then estimating the initial degree of subcriticality from observation of the resulting reactor period. While similar to inverse kinetics, the perturbed reactivity method differs in that the net reactivity present in the core is treated as two separate entities. The first is that associated with the known perturbation. This quantity, together with the observed period and the reactor's describing parameters, are the inputs to the method's implementing algorithm. The second entity, which is the algorithm;s output, is the sum of all other reactivities including those resulting from inherent feedback and the initial degree of subcriticality. During an automated startup, feedback effects will be minimal. Hence, when applied to a shutdown reactor, the output of the perturbed reactivity method will be a constant that is equal to the initial degree of subcriticality. This is a major advantage because repeated estimates can be made of this one quantity and signal smoothing techniques can be applied to enhance accuracy. In addition to describing the theoretical basis for the perturbed reactivity method, factors involved in its implementation such as the movement of control devices other than those used to create the perturbation, source estimation, and techniques for data smoothing are presented

  13. [Study on influence factors of seed germination and seeding growth of Lonicera macranthoides].

    Science.gov (United States)

    Xu, Jin; Zhang, Ying; Cui, Guang-Lin; She, Yue-Hui; Li, Long-Yun

    2016-01-01

    In order to improve reproductive efficiency and quality standard, the influence factors of seed germination and seeding growth of Lonicera macranthoides werew studied. The fruit and seed morphological characteristics of L. macranthoides were observed, the seed water absorbing capacity was determined, and different wet sand stratification time, temperature and germination bed treatment were set up. The effects of the parameters on seed germination and seedling growth were analysed. There was no obstacles of water absorption on L. macranthoides seed, quantity for 22 h water absorption was close to saturation. In the first 80 d, with the increase of the stratification time, seed initial germination time was shortened, germination rate and germination potential was improved. Stratification for 100 d, germination rate decreased. At 15 ℃, seed germination and seedling growth indicators were the best. The seedling cotyledon width in light was significantly higher than that in dark. Seeds on the top of paper and top of sand germination rate, germination potential, and germination index was significantly higher than that of other germination bed and mildew rate is low. The optimal conditions of seeds germination test was stratified in 4 ℃ wet sand for 80 d, 15 ℃ illuminate culture on the top of paper or top of sand. The first seeding counting time was the 4th day after beginning the test, the final time was the 23th day. The germination potential statistical time was the 13th day after beginning the test. Copyright© by the Chinese Pharmaceutical Association.

  14. Vertical Propagation and Temporal Growth of Perturbations in the Winter Atmosphere

    Science.gov (United States)

    Christiansen, B.

    2001-12-01

    We present a general circulation model study of the temporal growth and vertically propagation of perturbations following vertical confined forcings. Both transient and sustained forcings are considered. The motivation for the study is the recent recognition of downward propagation of anomalies from the stratosphere to the troposphere and its implications both for medium range forecasts and for a possible physical mechanism for stratospheric impacts on weather and climate. The dynamical link might also offer a mechanism for changes in the upper atmosphere to affect the tropospheric climate. Here we are thinking of changes in trace gases such as ozone, but also of modulations of the upper atmospheric structure related to the 11-year solar cycle. The model atmosphere is chaotic and shows growth of perturbations no matter which level is forced. The perturbations grow to a size comparable to the variability of the unperturbed atmosphere on a time-scale of 20 - 25 days in the troposphere and 30 - 40 days in the stratosphere. After the initial period of growth the perturbations have the same structure as the unperturbed atmosphere. Although the forcing is restricted to the northern hemisphere the perturbations encompass the whole atmosphere and develop on the same time scale on both hemispheres. Perturbations grow with time squared both when zonal mean and single cell values are considered. Such a power law growth suggest the existence of a finite predictability time which is independent of the initial perturbation as long as it is small. In the unperturbed atmosphere the stratospheric variability has the form of downward propagating stratospheric vacillations. However, in the initial period of growth the perturbations do not propagate downward and seem in general uncoupled to the background vacillations. This suggests that the downward propagation is a robust feature determined more by the processes in the troposphere than the state of the stratosphere. We note that

  15. Non-adiabatic perturbations in Ricci dark energy model

    International Nuclear Information System (INIS)

    Karwan, Khamphee; Thitapura, Thiti

    2012-01-01

    We show that the non-adiabatic perturbations between Ricci dark energy and matter can grow both on superhorizon and subhorizon scales, and these non-adiabatic perturbations on subhorizon scales can lead to instability in this dark energy model. The rapidly growing non-adiabatic modes on subhorizon scales always occur when the equation of state parameter of dark energy starts to drop towards -1 near the end of matter era, except that the parameter α of Ricci dark energy equals to 1/2. In the case where α = 1/2, the rapidly growing non-adiabatic modes disappear when the perturbations in dark energy and matter are adiabatic initially. However, an adiabaticity between dark energy and matter perturbations at early time implies a non-adiabaticity between matter and radiation, this can influence the ordinary Sachs-Wolfe (OSW) effect. Since the amount of Ricci dark energy is not small during matter domination, the integrated Sachs-Wolfe (ISW) effect is greatly modified by density perturbations of dark energy, leading to a wrong shape of CMB power spectrum. The instability in Ricci dark energy is difficult to be alleviated if the effects of coupling between baryon and photon on dark energy perturbations are included

  16. Hard exudates segmentation based on learned initial seeds and iterative graph cut.

    Science.gov (United States)

    Kusakunniran, Worapan; Wu, Qiang; Ritthipravat, Panrasee; Zhang, Jian

    2018-05-01

    (Background and Objective): The occurrence of hard exudates is one of the early signs of diabetic retinopathy which is one of the leading causes of the blindness. Many patients with diabetic retinopathy lose their vision because of the late detection of the disease. Thus, this paper is to propose a novel method of hard exudates segmentation in retinal images in an automatic way. (Methods): The existing methods are based on either supervised or unsupervised learning techniques. In addition, the learned segmentation models may often cause miss-detection and/or fault-detection of hard exudates, due to the lack of rich characteristics, the intra-variations, and the similarity with other components in the retinal image. Thus, in this paper, the supervised learning based on the multilayer perceptron (MLP) is only used to identify initial seeds with high confidences to be hard exudates. Then, the segmentation is finalized by unsupervised learning based on the iterative graph cut (GC) using clusters of initial seeds. Also, in order to reduce color intra-variations of hard exudates in different retinal images, the color transfer (CT) is applied to normalize their color information, in the pre-processing step. (Results): The experiments and comparisons with the other existing methods are based on the two well-known datasets, e_ophtha EX and DIARETDB1. It can be seen that the proposed method outperforms the other existing methods in the literature, with the sensitivity in the pixel-level of 0.891 for the DIARETDB1 dataset and 0.564 for the e_ophtha EX dataset. The cross datasets validation where the training process is performed on one dataset and the testing process is performed on another dataset is also evaluated in this paper, in order to illustrate the robustness of the proposed method. (Conclusions): This newly proposed method integrates the supervised learning and unsupervised learning based techniques. It achieves the improved performance, when compared with the

  17. Perturbations in electromagnetic dark energy

    International Nuclear Information System (INIS)

    Jiménez, Jose Beltrán; Maroto, Antonio L.; Koivisto, Tomi S.; Mota, David F.

    2009-01-01

    It has been recently proposed that the presence of a temporal electromagnetic field on cosmological scales could explain the phase of accelerated expansion that the universe is currently undergoing. The field contributes as a cosmological constant and therefore, the homogeneous cosmology produced by such a model is exactly the same as that of ΛCDM. However, unlike a cosmological constant term, electromagnetic fields can acquire perturbations which in principle could affect CMB anisotropies and structure formation. In this work, we study the evolution of inhomogeneous scalar perturbations in this model. We show that provided the initial electromagnetic fluctuations generated during inflation are small, the model is perfectly compatible with both CMB and large scale structure observations at the same level of accuracy as ΛCDM

  18. The Germination of Some Species Tropical Legume Seeds

    Directory of Open Access Journals (Sweden)

    Eko Poetri

    2005-09-01

    Full Text Available A study to evaluate the seed germination of Leucaena pallida under climatic and soil conditions in Palu was conducted in village of Taipa, Sub district of North Palu, District of Palu. To compare with other species of legume trees however, this study involved Leucaena leucocephala cv Tarramba, Leucaena leucocephala cv Gumph and Gliricidia maculata. This experiment used completely randomized design with species of tropical tree legumes as treatment.  Each treatment was replicated five times.  Each experimental unit consisted of one tray (size 12.5 x 25 cm and planted by 20 seed.  Each tray was filled with soil while the seeds were planted one cm deep.  All seeds were immersed in warm water (600C for five minutes before planted.  The base of the trays were drilled to create some holes for water to drain out.  The trays were sprayed twice daily (07.00 am and 03.00 pm to keep the soil to be moist using a very smooth sprayer.  The variables recorded included the initiation time of germination, the range time of germination and the percentage of seed germination.  The data obtained were analyses using the Minitab 11. Least significance difference was used to test for possible differences between treatment means. The result revealed that initiation time of germination and the range of germination were not varied (P>0.05 among the seeds tested. The initiation time of germination ranged between 9 to 12 d after sowing.  Gliricidia maculata seed has the shortest period to germinate (12-16 d after sowing, meanwhile Leucaena leucocephala cv. Tarramba appear to be the longest (9-17 d after sowing. The highest seed viability was 60% in Leucaena leucocephala, cv Gump while the lowest was found in Gliricidia maculata (29%. In addition, both Leucaena pallida and Leucaena leucocephala cv Tarramba had medium seed germination (40% and 53% respectively. (Animal Production 7(3: 156-160 (2005Key Words: Seed, Germination, Tropical Leguminous

  19. QTLs for seed vigor-related traits identified in maize seeds germinated under artificial aging conditions.

    Science.gov (United States)

    Han, Zanping; Ku, Lixia; Zhang, Zhenzhen; Zhang, Jun; Guo, Shulei; Liu, Haiying; Zhao, Ruifang; Ren, Zhenzhen; Zhang, Liangkun; Su, Huihui; Dong, Lei; Chen, Yanhui

    2014-01-01

    High seed vigor is important for agricultural production due to the associated potential for increased growth and productivity. However, a better understanding of the underlying molecular mechanisms is required because the genetic basis for seed vigor remains unknown. We used single-nucleotide polymorphism (SNP) markers to map quantitative trait loci (QTLs) for four seed vigor traits in two connected recombinant inbred line (RIL) maize populations under four treatment conditions during seed germination. Sixty-five QTLs distributed between the two populations were identified and a meta-analysis was used to integrate genetic maps. Sixty-one initially identified QTLs were integrated into 18 meta-QTLs (mQTLs). Initial QTLs with contribution to phenotypic variation values of R(2)>10% were integrated into mQTLs. Twenty-three candidate genes for association with seed vigor traits coincided with 13 mQTLs. The candidate genes had functions in the glycolytic pathway and in protein metabolism. QTLs with major effects (R(2)>10%) were identified under at least one treatment condition for mQTL2, mQTL3-2, and mQTL3-4. Candidate genes included a calcium-dependent protein kinase gene (302810918) involved in signal transduction that mapped in the mQTL3-2 interval associated with germination energy (GE) and germination percentage (GP), and an hsp20/alpha crystallin family protein gene (At5g51440) that mapped in the mQTL3-4 interval associated with GE and GP. Two initial QTLs with a major effect under at least two treatment conditions were identified for mQTL5-2. A cucumisin-like Ser protease gene (At5g67360) mapped in the mQTL5-2 interval associated with GP. The chromosome regions for mQTL2, mQTL3-2, mQTL3-4, and mQTL5-2 may be hot spots for QTLs related to seed vigor traits. The mQTLs and candidate genes identified in this study provide valuable information for the identification of additional quantitative trait genes.

  20. QTLs for seed vigor-related traits identified in maize seeds germinated under artificial aging conditions.

    Directory of Open Access Journals (Sweden)

    Zanping Han

    Full Text Available High seed vigor is important for agricultural production due to the associated potential for increased growth and productivity. However, a better understanding of the underlying molecular mechanisms is required because the genetic basis for seed vigor remains unknown. We used single-nucleotide polymorphism (SNP markers to map quantitative trait loci (QTLs for four seed vigor traits in two connected recombinant inbred line (RIL maize populations under four treatment conditions during seed germination. Sixty-five QTLs distributed between the two populations were identified and a meta-analysis was used to integrate genetic maps. Sixty-one initially identified QTLs were integrated into 18 meta-QTLs (mQTLs. Initial QTLs with contribution to phenotypic variation values of R(2>10% were integrated into mQTLs. Twenty-three candidate genes for association with seed vigor traits coincided with 13 mQTLs. The candidate genes had functions in the glycolytic pathway and in protein metabolism. QTLs with major effects (R(2>10% were identified under at least one treatment condition for mQTL2, mQTL3-2, and mQTL3-4. Candidate genes included a calcium-dependent protein kinase gene (302810918 involved in signal transduction that mapped in the mQTL3-2 interval associated with germination energy (GE and germination percentage (GP, and an hsp20/alpha crystallin family protein gene (At5g51440 that mapped in the mQTL3-4 interval associated with GE and GP. Two initial QTLs with a major effect under at least two treatment conditions were identified for mQTL5-2. A cucumisin-like Ser protease gene (At5g67360 mapped in the mQTL5-2 interval associated with GP. The chromosome regions for mQTL2, mQTL3-2, mQTL3-4, and mQTL5-2 may be hot spots for QTLs related to seed vigor traits. The mQTLs and candidate genes identified in this study provide valuable information for the identification of additional quantitative trait genes.

  1. Perturbing engine performance measurements to determine optimal engine control settings

    Science.gov (United States)

    Jiang, Li; Lee, Donghoon; Yilmaz, Hakan; Stefanopoulou, Anna

    2014-12-30

    Methods and systems for optimizing a performance of a vehicle engine are provided. The method includes determining an initial value for a first engine control parameter based on one or more detected operating conditions of the vehicle engine, determining a value of an engine performance variable, and artificially perturbing the determined value of the engine performance variable. The initial value for the first engine control parameter is then adjusted based on the perturbed engine performance variable causing the engine performance variable to approach a target engine performance variable. Operation of the vehicle engine is controlled based on the adjusted initial value for the first engine control parameter. These acts are repeated until the engine performance variable approaches the target engine performance variable.

  2. EDITORIAL: Non-linear and non-Gaussian cosmological perturbations Non-linear and non-Gaussian cosmological perturbations

    Science.gov (United States)

    Sasaki, Misao; Wands, David

    2010-06-01

    In recent years there has been a resurgence of interest in the study of non-linear perturbations of cosmological models. This has been the result of both theoretical developments and observational advances. New theoretical challenges arise at second and higher order due to mode coupling and the need to develop new gauge-invariant variables beyond first order. In particular, non-linear interactions lead to deviations from a Gaussian distribution of primordial perturbations even if initial vacuum fluctuations are exactly Gaussian. These non-Gaussianities provide an important probe of models for the origin of structure in the very early universe. We now have a detailed picture of the primordial distribution of matter from surveys of the cosmic microwave background, notably NASA's WMAP satellite. The situation will continue to improve with future data from the ESA Planck satellite launched in 2009. To fully exploit these data cosmologists need to extend non-linear cosmological perturbation theory beyond the linear theory that has previously been sufficient on cosmological scales. Another recent development has been the realization that large-scale structure, revealed in high-redshift galaxy surveys, could also be sensitive to non-linearities in the primordial curvature perturbation. This focus section brings together a collection of invited papers which explore several topical issues in this subject. We hope it will be of interest to theoretical physicists and astrophysicists alike interested in understanding and interpreting recent developments in cosmological perturbation theory and models of the early universe. Of course it is only an incomplete snapshot of a rapidly developing field and we hope the reader will be inspired to read further work on the subject and, perhaps, fill in some of the missing pieces. This focus section is dedicated to the memory of Lev Kofman (1957-2009), an enthusiastic pioneer of inflationary cosmology and non-Gaussian perturbations.

  3. Initial characterisation of low and high seed dormancy populations of Lolium rigidum produced by repeated selection.

    Science.gov (United States)

    Goggin, Danica E; Emery, R J Neil; Powles, Stephen B; Steadman, Kathryn J

    2010-10-15

    The physiological and biochemical bases of seed dormancy in Lolium rigidum (annual ryegrass) are largely unknown, and study of this process is complicated by the outcrossing nature of the species and the strong influence of environment on seed dormancy. In order to identify heritable biochemical factors contributing to seed dormancy in L. rigidum, seeds from a field-collected population were used to select sub-populations with consistently low or high seed dormancy over four generations. Low-dormancy seeds showed constitutive alpha-amylase activity prior to imbibition, higher concentrations of polyphenols and cis-zeatin, and lower abscisic acid and cis-zeatin riboside concentrations than high-dormancy seeds. Selection for high dormancy was associated with a reduction in response to dark-stratification for 21d at 20 degrees C (an effective means of releasing dormancy in the original, unselected population) over successive generations, but fluridone remained effective in breaking dormancy. Crossing of low- and high-dormancy populations indicated that dormancy level was not dependent upon the maternal genotype of the seed, and that the constitutive alpha-amylase activity and high seed anthocyanin concentrations characteristic of the low-dormancy populations were not correlated to high basal germination ability. Copyright (c) 2010 Elsevier GmbH. All rights reserved.

  4. Perturbative QCD and exclusive processes

    International Nuclear Information System (INIS)

    Bennett, J.; Hawes, F.; Zhao, M.; Zyla, P.

    1991-01-01

    The authors discuss perturbation theory as applied to particle physics calculations. In particle physics one is generally interested in the scattering amplitude for a system going from some initial state to a final state. The intermediate state or states are unknown. To get the scattering amplitude it is necessary to sum the contributions from processes which pass through all possible intermediate states. Intermediate states involve the exchange of intermediate vector bosons between the particles, and with this interaction is associated a coupling constant α. Each additional boson exchange involves an additional contribution of α to the coupling. If α is less than 1, one can see that the relative contribution of higher order processes is less and less important as α falls. In QCD the gluons serve as the intermediate vector bosons exchanged by quarks and gluons, and the interaction constant is not really a constant, but depends upon the distance between the particles. At short distances the coupling is small, and one can assume perturbative expansions may converge rapidly. Exclusive scattering processes, as opposed to inclusive, are those in which all of the final state products are detected. The authors then discuss the application of perturbative QCD to the deuteron. The issues of chiral conservation and color transparancy are also discussed, in the scheme of large Q 2 interations, where perturbative QCD should be applicable

  5. The effect of altitude on breaking seed dormancy and stimulation of seed germination of Persian hogweed (Heracleum persicum).

    Science.gov (United States)

    Salehani, M Khajavi; Mahmoudi, J; Mahdavi, S Kh; Habibzadeh, R

    2013-01-01

    Persian hogweed is a perennial herb and aromatic plant which has pharmaceutical and fodder values, and the main propagation method of this species is seed. The goal of this study was to investigate the effect of altitude on breaking dormancy and stimulate seed germination of this species. The study was designed and carried out using the test of seed analysis. For our purpose, seeds were collected from three different altitudes (1700, 2200, 2700 masl) in Kojoor area. After initial purification, germination percent (GP) and speed (GS) of each elevation were determined by cold stratification compared to control. According to results, control seeds did not germinate, showing that the seeds of this species need to be treated. Statistical analysis of results showed that there are significant differences between GP and GS of each elevation, as seeds of higher elevation had slower and less germination in longer periods. So, changes in elevation are an effective factor on seed germination characteristics of this species and this factor has to be considered in seed preparation and restoration with this species.

  6. Seed dormancy and germination.

    Science.gov (United States)

    Penfield, Steven

    2017-09-11

    Reproduction is a critical time in plant life history. Therefore, genes affecting seed dormancy and germination are among those under strongest selection in natural plant populations. Germination terminates seed dispersal and thus influences the location and timing of plant growth. After seed shedding, germination can be prevented by a property known as seed dormancy. In practise, seeds are rarely either dormant or non-dormant, but seeds whose dormancy-inducing pathways are activated to higher levels will germinate in an ever-narrower range of environments. Thus, measurements of dormancy must always be accompanied by analysis of environmental contexts in which phenotypes or behaviours are described. At its simplest, dormancy can be imposed by the formation of a simple physical barrier around the seed through which gas exchange and the passage of water are prevented. Seeds featuring this so-called 'physical dormancy' often require either scarification or passage through an animal gut (replete with its associated digestive enzymes) to disrupt the barrier and permit germination. In other types of seeds with 'morphological dormancy' the embryo remains under-developed at maturity and a dormant phase exists as the embryo continues its growth post-shedding, eventually breaking through the surrounding tissues. By far, the majority of seeds exhibit 'physiological dormancy' - a quiescence program initiated by either the embryo or the surrounding endosperm tissues. Physiological dormancy uses germination-inhibiting hormones to prevent germination in the absence of the specific environmental triggers that promote germination. During and after germination, early seedling growth is supported by catabolism of stored reserves of protein, oil or starch accumulated during seed maturation. These reserves support cell expansion, chloroplast development and root growth until photoauxotrophic growth can be resumed. Crown Copyright © 2017. Published by Elsevier Ltd. All rights reserved.

  7. Evaluating results from the Relativistic Heavy Ion Collider with perturbative QCD and hydrodynamics

    Energy Technology Data Exchange (ETDEWEB)

    Fries, R.J.; Nonaka, C.

    2011-07-01

    We review the basic concepts of perturbative quantum chromodynamics (QCD) and relativistic hydrodynamics, and their applications to hadron production in high energy nuclear collisions. We discuss results from the Relativistic Heavy Ion Collider (RHIC) in light of these theoretical approaches. Perturbative QCD and hydrodynamics together explain a large amount of experimental data gathered during the first decade of RHIC running, although some questions remain open. We focus primarily on practical aspects of the calculations, covering basic topics like perturbation theory, initial state nuclear effects, jet quenching models, ideal hydrodynamics, dissipative corrections, freeze-out and initial conditions. We conclude by comparing key results from RHIC to calculations.

  8. Development of transgenic Brassica juncea lines for reduced seed sinapine content by perturbing phenylpropanoid pathway genes.

    Directory of Open Access Journals (Sweden)

    Sachin Kajla

    Full Text Available Sinapine is a major anti-nutritive compound that accumulates in the seeds of Brassica species. When ingested, sinapine imparts gritty flavuor in meat and milk of animals and fishy odor to eggs of brown egg layers, thereby compromising the potential use of the valuable protein rich seed meal. Sinapine content in Brassica juncea germplasm ranges from 6.7 to 15.1 mg/g of dry seed weight (DSW which is significantly higher than the prescribed permissible level of 3.0 mg/g of DSW. Due to limited natural genetic variability, conventional plant breeding approach for reducing the sinapine content has largely been unsuccessful. Hence, transgenic approach for gene silencing was adopted by targeting two genes-SGT and SCT, encoding enzymes UDP- glucose: sinapate glucosyltransferase and sinapoylglucose: choline sinapoyltransferase, respectively, involved in the final two steps of sinapine biosynthetic pathway. These two genes were isolated from B. juncea and eight silencing constructs were developed using three different RNA silencing approaches viz. antisense RNA, RNAi and artificial microRNA. Transgenics in B. juncea were developed following Agrobacterium-mediated transformation. From a total of 1232 independent T0 transgenic events obtained using eight silencing constructs, 25 homozygous lines showing single gene inheritance were identified in the T2 generation. Reduction of seed sinapine content in these lines ranged from 15.8% to 67.2%; the line with maximum reduction had sinapine content of 3.79 mg/g of DSW. The study also revealed that RNAi method was more efficient than the other two methods used in this study.

  9. Engineering properties of sunflower seed: Effect of dehulling and moisture content

    Directory of Open Access Journals (Sweden)

    Mudasir Ahmad Malik

    2016-12-01

    Full Text Available The study diagnosed engineering properties on varying moisture content of sunflower seed and kernel from 7.6 to 25% (wet basis. On increasing moisture, dimensional values increased for both seed and kernel. Bulk density, true density and porosity were found higher for kernel as compared to seed at each moisture content. On increasing the moisture content from 7.6 to 25%, true density, porosity and thousand kernel weight increased. Coefficient of static friction on plywood was found maximum for kernel at 25% moisture content, while it was minimum for seed on glass at 7.6% moisture content. The angle of repose was maximum for kernel as compared to seed. Initial cracking force, average rupture force and average rupture energy for seed and kernel decreased with an increase in the moisture content. The kernel was found to be more resistant to initial cracking than seed.

  10. Physiological and proteomic analyses on artificially aged Brassica napus seed

    Directory of Open Access Journals (Sweden)

    Pingfang eYang

    2015-02-01

    Full Text Available Plant seeds lose their viability when they are exposed to long term storage or controlled deterioration treatments, by a process known as seed ageing. Based on previous studies, artificially ageing treatments have been developed to accelerate the process of seed ageing in order to understand its underlying mechanisms. In this study, we used Brassica napus seeds to investigate the mechanisms of ageing initiation. B. napus seeds were exposed to artificially ageing treatment (40 oC and 90% relative humidity and their physio-biochemical characteristics were analyzed. Although the treatment delayed germination, it did not increase the concentration of cellular reactive oxygen species (ROS. Comparative proteomic analysis was conducted among the control and treated seeds at different stages of germination. The proteins responded to the treatment were mainly involved in metabolism, protein modification and destination, stress response, development and miscellaneous enzymes. Except for peroxiredoxin, no changes were observed in the accumulation of other antioxidant enzymes in the artificially aged seeds. Increased content of ABA was observed in the artificially treated seeds which might be involved in the inhibition of germination. Taken together, our results highlight the involvement of ABA in the initiation of seed ageing in addition to the ROS which was previously reported to mediate the seed ageing process.

  11. Anomalous, extreme weather disrupts obligate seed dispersal mutualism: snow in a subtropical forest ecosystem.

    Science.gov (United States)

    Zhou, Youbing; Newman, Chris; Chen, Jin; Xie, Zongqiang; Macdonald, David W

    2013-09-01

    Ongoing global climate change is predicted to increase the frequency and magnitude of extreme weather events, impacting population dynamics and community structure. There is, however, a critical lack of case studies considering how climatic perturbations affect biotic interactions. Here, we document how an obligate seed dispersal mutualism was disrupted by a temporally anomalous and meteorologically extreme interlude of unseasonably frigid weather, with accompanying snowstorms, in subtropical China, during January-February 2008. Based on the analysis of 5892 fecal samples (representing six mammalian seed dispersers), this event caused a substantial disruption to the relative seed dispersal function for the raisin tree Hovenia dulcis from prestorm 6.29 (2006) and 11.47 (2007), down to 0.35 during the storm (2008). Crucially, this was due to impacts on mammalian seed dispersers and not due to a paucity of fruit, where 4.63 fruit per branch were available in January 2008, vs. 3.73 in 2006 and 3.58 in 2007. An induced dietary shift occurred among omnivorous carnivores during this event, from the consumption fruit to small mammals and birds, reducing their role in seed dispersal substantially. Induced range shift extinguished the functionality of herbivorous mammals completely, however, seed dispersal function was compensated in part by three omnivorous carnivores during poststorm years, and thus while the mutualism remained intact it was enacted by a narrower assemblage of species, rendering the system more vulnerable to extrinsic perturbations. The storm's extended effects also had anthropogenic corollaries - migrating ungulates becoming exposed to heightened levels of illegal hunting - causing long-term modification to the seed dispersal community and mutualism dynamics. Furthermore, degraded forests proved especially vulnerable to the storm's effects. Considering increasing climate variability and anthropogenic disturbance, the impacts of such massive, aberrant

  12. Imazapyr (herbicide) seed dressing increases yield, suppresses ...

    African Journals Online (AJOL)

    from damage. In 1998/99 season, a trial was initiated at Chitedze Research Station under artificial infection, to evaluate the effects of seed dressing with imazapyr (an acetolactate synthase {ALS} inhibiting herbicide) using three seed treatment methods (coating, priming or drenching) and three herbicide rates (15, 30 and 45 ...

  13. Cosmological perturbations on the phantom brane

    Energy Technology Data Exchange (ETDEWEB)

    Bag, Satadru; Sahni, Varun [Inter-University Centre for Astronomy and Astrophysics, Pune (India); Viznyuk, Alexander; Shtanov, Yuri, E-mail: satadru@iucaa.in, E-mail: viznyuk@bitp.kiev.ua, E-mail: shtanov@bitp.kiev.ua, E-mail: varun@iucaa.in [Bogolyubov Institute for Theoretical Physics, Kiev 03680 (Ukraine)

    2016-07-01

    We obtain a closed system of equations for scalar perturbations in a multi-component braneworld. Our braneworld possesses a phantom-like equation of state at late times, w {sub eff} < −1, but no big-rip future singularity. In addition to matter and radiation, the braneworld possesses a new effective degree of freedom—the 'Weyl fluid' or 'dark radiation'. Setting initial conditions on super-Hubble spatial scales at the epoch of radiation domination, we evolve perturbations of radiation, pressureless matter and the Weyl fluid until the present epoch. We observe a gradual decrease in the amplitude of the Weyl-fluid perturbations after Hubble-radius crossing, which results in a negligible effect of the Weyl fluid on the evolution of matter perturbations on spatial scales relevant for structure formation. Consequently, the quasi-static approximation of Koyama and Maartens provides a good fit to the exact results during the matter-dominated epoch. We find that the late-time growth of density perturbations on the brane proceeds at a faster rate than in ΛCDM. Additionally, the gravitational potentials Φ and Ψ evolve differently on the brane than in ΛCDM, for which Φ = Ψ. On the brane, by contrast, the ratio Φ/Ψ exceeds unity during the late matter-dominated epoch ( z ∼< 50). These features emerge as smoking gun tests of phantom brane cosmology and allow predictions of this scenario to be tested against observations of galaxy clustering and large-scale structure.

  14. The perturbative (QCD) Pomeron and Odderon in the photon initiated reactions

    International Nuclear Information System (INIS)

    Ginzburg, I.F.

    1992-07-01

    The cross sections of neutral meson M production in the exclusive γγ → MM', γq → Mq or semiexclusive γγ → MX processes (two or three gluon exchange) in the semihard region s≥|t|>1 GeV 2 , μ 2 ≤M X 2 <|t| are calculated. The relation of investigated processes to the problem of the perturbative Pomeron and Odderon is discussed. The possibility of measurements is also discussed. (author) 23 refs.; 3 figs

  15. Constraints on the production of primordial magnetic seeds in pre-big bang cosmology

    Science.gov (United States)

    Gasperini, M.

    2017-06-01

    We study the amplification of the electromagnetic fluctuations, and the production of "seeds" for the cosmic magnetic fields, in a class of string cosmology models whose scalar and tensor perturbations reproduce current observations and satisfy known phenomenological constraints. We find that the condition of efficient seeds production can be satisfied and compatible with all constraints only in a restricted region of parameter space, but we show that such a region has significant intersections with the portions of parameter space where the produced background of relic gravitational waves is strong enough to be detectable by aLIGO/Virgo and/or by eLISA.

  16. Shadowing of gluons in perturbative QCD: A comparison of different models

    International Nuclear Information System (INIS)

    Jalilian-Marian, Jamal; Wang, Xin-Nian

    2001-01-01

    We investigate the different perturbative QCD-based models for nuclear shadowing of gluons. We show that, in the kinematic region appropriate to the BNL relativistic heavy ion collider experiment, all models give similar estimates for the magnitude of gluon shadowing. At scales relevant to CERN large hadron collider (LHC), there is a sizable difference between the predictions of the different models. However, the uncertainties in gluon shadowing coming from a different parametrization of the gluon distribution in nucleons, are larger than those due to different perturbative QCD models of gluon shadowing. We also investigate the effect of initial nonperturbative shadowing on the magnitude of perturbative shadowing and show that the magnitudes of perturbative and nonperturbative shadowing are comparable at RHIC but perturbative shadowing dominates over nonperturbative shadowing at smaller values of x reached at LHC

  17. Influence of asymmetric magnetic perturbation on the nonlinear evolution of double tearing modes

    Science.gov (United States)

    Xiong, G. Z.; Wang, L.; Li, X. Q.; Liu, H. F.; Tang, C. J.; Huang, J.; Zhang, X.; Wang, X. Q.

    2017-06-01

    The effects of asymmetric magnetic perturbation on the triggering and evolution of double tearing modes (DTMs) are investigated using nonlinear magnetohydrodynamics simulations in a slab geometry. We find that for reversed magnetic shear plasmas the resistive reconnection process induced by the initial perturbation at one rational surface can drive a new island at the other rational surface with the same mode number. The four typical states of the mode for the time evolution are found, and include: (i) a linear growth stage; (ii) a linear/nonlinear stable stage; (iii) an interactively driving stage; and (iv) a symmetric DTM stage. These differ from previous simulation results. Moreover, nonlinear DTM growth is found to strongly depend on the asymmetric magnetic perturbation, particularly in the early nonlinear phase. The initial perturbation strength scale of island width suggests that the left island enters into a Sweet-Parker growth process when the right island is sufficiently large to effectively drive the other. These results predict that although externally applied magnetic perturbations can suppress the neoclassical tearing mode they can also trigger new instabilities such as asymmetric DTMs.

  18. Influence of asymmetric magnetic perturbation on the nonlinear evolution of double tearing modes

    International Nuclear Information System (INIS)

    Xiong, G Z; Liu, H F; Huang, J; Wang, X Q; Wang, L; Li, X Q; Tang, C J; Zhang, X

    2017-01-01

    The effects of asymmetric magnetic perturbation on the triggering and evolution of double tearing modes (DTMs) are investigated using nonlinear magnetohydrodynamics simulations in a slab geometry. We find that for reversed magnetic shear plasmas the resistive reconnection process induced by the initial perturbation at one rational surface can drive a new island at the other rational surface with the same mode number. The four typical states of the mode for the time evolution are found, and include: (i) a linear growth stage; (ii) a linear/nonlinear stable stage; (iii) an interactively driving stage; and (iv) a symmetric DTM stage. These differ from previous simulation results. Moreover, nonlinear DTM growth is found to strongly depend on the asymmetric magnetic perturbation, particularly in the early nonlinear phase. The initial perturbation strength scale of island width suggests that the left island enters into a Sweet–Parker growth process when the right island is sufficiently large to effectively drive the other. These results predict that although externally applied magnetic perturbations can suppress the neoclassical tearing mode they can also trigger new instabilities such as asymmetric DTMs. (paper)

  19. Use of Moringa oleifera seeds for the removal of turbidity of water supply

    Directory of Open Access Journals (Sweden)

    Gustavo Lopes Muniz

    2015-04-01

    Full Text Available Water used for human consumption may contain various impurities and solid particles in suspension that increase its turbidity level. Moringa oleifera Lam is a plant that has the potential to be used as coagulating agent in removing turbidity. The objective of this work was to evaluate the efficiency of Moringa oleifera seeds used in shells and without shells in the removal of turbidity from waters with different degrees of turbidity. Waters were used with 70, 250 and 400 initial NTU obtained synthetically. The extract of moringa seeds was prepared using unshelled and shelled seeds, seeking a simplified procedure and practice. The sedimentation times and dose of coagulant solution used were based on existing recommendations in the literature. All treatments were performed with three replicates and the averages depicted in graphs. The results showed that the use of extract of moringa seeds in shells was more efficient than with unshelled seeds in the removal of turbidity of all treatments and that the shelled seeds removed more than 99% of the initial turbidity of the water samples. Furthermore, there was a direct relationship between turbidity removal efficiency and the level of initial turbidity of the samples. The seeds were more efficient in removing turbidity of the water with a higher level of initial turbidity.

  20. Commercial Scale Production of Mushroom Liquid Seeds

    International Nuclear Information System (INIS)

    Rosnani Abdul Rashid; Hassan Hamdani Hassan Mutaat; Mohd Meswan Maskom; Khairuddin Abdul Rahim

    2015-01-01

    Mushroom liquid seed production technology was developed by Malaysian Nuclear Agency (Nuclear Malaysia) in the late 1990s. Initially, the liquid seeds were used mainly in the solid state fermentation process for converting oil palm empty fruit bunch fibres into ruminant feed. Considering widespread problems encountered by mushroom growers from use of solid seeds, especially in cases of contaminant agents infecting cultivated bags and inconsistencies in yield, we diverted our focus to utilising liquid seeds as alternative inocula for mushroom cultivation. These problems provide us opportunities to look into the issues and address the problems faced by mushroom growers. However, the technology of producing liquid seed at laboratory scale needs to be primed for commercial production. This paper discusses developmental aspects of mushroom liquid seed at commercial scale for the advancement of the country's mushroom industry. (author)

  1. Supersingular quantum perturbations

    International Nuclear Information System (INIS)

    Detwiler, L.C.; Klauder, J.R.

    1975-01-01

    A perturbation potential is called supersingular whenever generally every matrix element of the perturbation in the unperturbed eigenstates is infinite. It follows that supersingular perturbations do not have conventional perturbation expansions, say for energy eigenvalues. By invoking variational arguments, we determine the asymptotic behavior of the energy eigenvalues for asymptotically small values of the coupling constant of the supersingular perturbation

  2. Boundary Layer Instabilities Generated by Freestream Laser Perturbations

    Science.gov (United States)

    Chou, Amanda; Schneider, Steven P.

    2015-01-01

    A controlled, laser-generated, freestream perturbation was created in the freestream of the Boeing/AFOSR Mach-6 Quiet Tunnel (BAM6QT). The freestream perturbation convected downstream in the Mach-6 wind tunnel to interact with a flared cone model. The geometry of the flared cone is a body of revolution bounded by a circular arc with a 3-meter radius. Fourteen PCB 132A31 pressure transducers were used to measure a wave packet generated in the cone boundary layer by the freestream perturbation. This wave packet grew large and became nonlinear before experiencing natural transition in quiet flow. Breakdown of this wave packet occurred when the amplitude of the pressure fluctuations was approximately 10% of the surface pressure for a nominally sharp nosetip. The initial amplitude of the second mode instability on the blunt flared cone is estimated to be on the order of 10 -6 times the freestream static pressure. The freestream laser-generated perturbation was positioned upstream of the model in three different configurations: on the centerline, offset from the centerline by 1.5 mm, and offset from the centerline by 3.0 mm. When the perturbation was offset from the centerline of a blunt flared cone, a larger wave packet was generated on the side toward which the perturbation was offset. The offset perturbation did not show as much of an effect on the wave packet on a sharp flared cone as it did on a blunt flared cone.

  3. Development of a new bioprocess scheme using frozen seed train intermediates to initiate CHO cell culture manufacturing campaigns.

    Science.gov (United States)

    Seth, Gargi; Hamilton, Robert W; Stapp, Thomas R; Zheng, Lisa; Meier, Angela; Petty, Krista; Leung, Stephenie; Chary, Srikanth

    2013-05-01

    Agility to schedule and execute cell culture manufacturing campaigns quickly in a multi-product facility will play a key role in meeting the growing demand for therapeutic proteins. In an effort to shorten campaign timelines, maximize plant flexibility and resource utilization, we investigated the initiation of cell culture manufacturing campaigns using CHO cells cryopreserved in large volume bags in place of the seed train process flows that are conventionally used in cell culture manufacturing. This approach, termed FASTEC (Frozen Accelerated Seed Train for Execution of a Campaign), involves cultivating cells to high density in a perfusion bioreactor, and cryopreserving cells in multiple disposable bags. Each run for a manufacturing campaign would then come from a thaw of one or more of these cryopreserved bags. This article reviews the development and optimization of individual steps of the FASTEC bioprocess scheme: scaling up cells to greater than 70 × 10(6) cells/mL and freezing in bags with an optimized controlled rate freezing protocol and using a customized rack configuration. Flow cytometry analysis was also employed to understand the recovery of CHO cells following cryopreservation. Extensive development data were gathered to ensure that the quantity and quality of the drug manufactured using the FASTEC bioprocess scheme was acceptable compared to the conventional seed train process flow. The result of offering comparable manufacturing options offers flexibility to the cell culture manufacturing network. Copyright © 2012 Wiley Periodicals, Inc.

  4. Singularly perturbed Burger-Huxley equation: Analytical solution ...

    African Journals Online (AJOL)

    The work presented considers the initial boundary value problem for nonlinear singularly perturbed time dependent Burger- Huxley equation. The equation contains two terms with nonlinearities, the cubic term and the advection term. Generally, the severe difficulties of two types encounter in solving this problem. The first ...

  5. Fluridone and norflurazon, carotenoid-biosynthesis inhibitors, promote seed conditioning and germination of the holoparasite Orobanche minor.

    Science.gov (United States)

    Chae, Sang Heon; Yoneyama, Koichi; Takeuchi, Yasutomo; Joel, Daniel M.

    2004-02-01

    Fluridone and norflurazon, two carotenoid-biosynthesis inhibitors, shortened the conditioning period required by seeds of Orobanche minor in order to respond to the germination stimulant strigol. Neither fluridone nor norflurazon alone induced seed germination of O. minor, they promoted strigol-induced germination. In addition, these compounds restored the conditioning and germination of seeds at a supraoptimal temperature (30 degrees C) as well as in the light. Gibberellic acid (GA(3)) showed similar promotive and protective effects on the conditioning and germination of O. minor seeds. Although fluridone and norflurazon are known to prevent abscisic acid (ABA)-biosynthesis, and stresses such as supraoptimal temperatures have been reported to induce ABA accumulation in plants, the amount of ABA in the seeds or that released from the seeds into the conditioning media was not affected by the fluridone treatment and by exposure to the supraoptimal temperature. These results indicate that the promotive and protective effects of fluridone and norflurazon on the conditioning and germination of O. minor seeds would be attributed to other perturbations rather than the inhibition of ABA-biosynthesis.

  6. An initial non-targeted analysis of the peanut seed metabolome

    Science.gov (United States)

    There are likely a large number of compounds that constitute the peanut seed metabolome that have yet to be elucidated. Although the proximate composition and nutrients such as vitamins and minerals are well known, the composition of many other small molecule metabolites present have not been syste...

  7. Seed quality in informal seed systems

    NARCIS (Netherlands)

    Biemond, P.C.

    2013-01-01

    Keywords: informal seed systems, seed recycling, seed quality, germination, seed pathology, seed health, seed-borne diseases, mycotoxigenic fungi, Fusarium verticillioides, mycotoxins, Vigna unguiculata, Zea mays, Nigeria.

    Seed is a crucial input for agricultural production.

  8. Where does cosmological perturbation theory break down?

    International Nuclear Information System (INIS)

    Armendariz-Picon, Cristian; Fontanini, Michele; Penco, Riccardo; Trodden, Mark

    2009-01-01

    It is often assumed that initial conditions for the evolution of a cosmological mode should be set at the time its physical wavelength reaches a cut-off of the order of the Planck length. Beyond that scale, trans-Planckian corrections to the dispersion relation are supposed to become dominant, leading to the breakdown of cosmological perturbation theory. In this paper, we apply the effective field theory approach to the coupled metric-inflaton system in order to calculate the corrections to the power spectrum of scalar and tensor perturbations induced by higher-dimension operators at short wavelengths. These corrections can be interpreted as modifications of the dispersion relation, and thus open a window to probe the validity of cosmological perturbation theory. Both for scalars and tensors, the modifications become important when the Hubble parameter is of the order of the Planck mass, or when the physical wave number of a cosmological perturbation mode approaches the square of the Planck mass divided by the Hubble constant. Thus, the cut-off length at which such a breakdown occurs is finite, but much smaller than the Planck length.

  9. Streamer properties and associated x-rays in perturbed air

    Science.gov (United States)

    Köhn, C.; Chanrion, O.; Babich, L. P.; Neubert, T.

    2018-01-01

    Streamers are ionization waves in electric discharges. One of the key ingredients of streamer propagation is an ambient gas that serves as a source of free electrons. Here, we explore the dependence of streamer dynamics on different spatial distributions of ambient air molecules. We vary the spatial profile of air parallel and perpendicular to the ambient electric field. We consider local sinusoidal perturbations of 5%-100%, as induced from discharge shock waves. We use a cylindrically symmetric particle-in-cell code to simulate the evolution of bidirectional streamers and compare the electron density, electric field, streamer velocity and electron energy of streamers in uniform air and in perturbed air. In all considered cases, the motion is driven along in decreasing air density and damped along increasing air density. Perturbations of at most 5%-10% change the velocity differences by up to approximately 40%. Perturbations perpendicular to the electric field additionally squeeze or branch streamers. Air variations can thus partly explain the difference of velocities and morphologies of streamer discharges. In cases with large perturbations, electrons gain energies of up to 30 keV compared to 100 eV in uniformly distributed air. For such perturbations parallel to the ambient electric field, we see the spontaneous initiation of a negative streamer; for perpendicular perturbations, x-rays with energies of up to 20 keV are emitted within 0.17 ns.

  10. Nonlinear Brillouin amplification of finite-duration seeds in the strong coupling regime

    International Nuclear Information System (INIS)

    Lehmann, G.; Spatschek, K. H.

    2013-01-01

    Parametric plasma processes received renewed interest in the context of generating ultra-intense and ultra-short laser pulses up to the exawatt-zetawatt regime. Both Raman as well as Brillouin amplifications of seed pulses were proposed. Here, we investigate Brillouin processes in the one-dimensional (1D) backscattering geometry with the help of numerical simulations. For optimal seed amplification, Brillouin scattering is considered in the so called strong coupling (sc) regime. Special emphasis lies on the dependence of the amplification process on the finite duration of the initial seed pulses. First, the standard plane-wave instability predictions are generalized to pulse models, and the changes of initial seed pulse forms due to parametric instabilities are investigated. Three-wave-interaction results are compared to predictions by a new (kinetic) Vlasov code. The calculations are then extended to the nonlinear region with pump depletion. Generation of different seed layers is interpreted by self-similar solutions of the three-wave interaction model. Similar to Raman amplification, shadowing of the rear layers by the leading layers of the seed occurs. The shadowing is more pronounced for initially broad seed pulses. The effect is quantified for Brillouin amplification. Kinetic Vlasov simulations agree with the three-wave interaction predictions and thereby affirm the universal validity of self-similar layer formation during Brillouin seed amplification in the strong coupling regime

  11. Predicting areas of sustainable error growth in quasigeostrophic flows using perturbation alignment properties

    Science.gov (United States)

    Rivière, G.; Hua, B. L.

    2004-10-01

    A new perturbation initialization method is used to quantify error growth due to inaccuracies of the forecast model initial conditions in a quasigeostrophic box ocean model describing a wind-driven double gyre circulation. This method is based on recent analytical results on Lagrangian alignment dynamics of the perturbation velocity vector in quasigeostrophic flows. More specifically, it consists in initializing a unique perturbation from the sole knowledge of the control flow properties at the initial time of the forecast and whose velocity vector orientation satisfies a Lagrangian equilibrium criterion. This Alignment-based Initialization method is hereafter denoted as the AI method.In terms of spatial distribution of the errors, we have compared favorably the AI error forecast with the mean error obtained with a Monte-Carlo ensemble prediction. It is shown that the AI forecast is on average as efficient as the error forecast initialized with the leading singular vector for the palenstrophy norm, and significantly more efficient than that for total energy and enstrophy norms. Furthermore, a more precise examination shows that the AI forecast is systematically relevant for all control flows whereas the palenstrophy singular vector forecast leads sometimes to very good scores and sometimes to very bad ones.A principal component analysis at the final time of the forecast shows that the AI mode spatial structure is comparable to that of the first eigenvector of the error covariance matrix for a "bred mode" ensemble. Furthermore, the kinetic energy of the AI mode grows at the same constant rate as that of the "bred modes" from the initial time to the final time of the forecast and is therefore characterized by a sustained phase of error growth. In this sense, the AI mode based on Lagrangian dynamics of the perturbation velocity orientation provides a rationale of the "bred mode" behavior.

  12. Non-perturbative versus perturbative renormalization of lattice operators

    International Nuclear Information System (INIS)

    Goeckeler, M.; Technische Hochschule Aachen; Horsley, R.; Ilgenfritz, E.M.; Oelrich, H.; Forschungszentrum Juelich GmbH; Schierholz, G.; Forschungszentrum Juelich GmbH; Perlt, H.; Schiller, A.; Rakow, P.

    1995-09-01

    Our objective is to compute the moments of the deep-inelastic structure functions of the nucleon on the lattice. A major source of uncertainty is the renormalization of the lattice operators that enter the calculation. In this talk we compare the renormalization constants of the most relevant twist-two bilinear quark operators which we have computed non-perturbatively and perturbatively to one loop order. Furthermore, we discuss the use of tadpole improved perturbation theory. (orig.)

  13. Fluid dynamic propagation of initial baryon number perturbations on a Bjorken flow background

    CERN Document Server

    Floerchinger, Stefan

    2015-01-01

    Baryon number density perturbations offer a possible route to experimentally measure baryon number susceptibilities and heat conductivity of the quark gluon plasma. We study the fluid dynamical evolution of local and event-by-event fluctuations of baryon number density, flow velocity and energy density on top of a (generalized) Bjorken expansion. To that end we use a background-fluctuation splitting and a Bessel-Fourier decomposition for the fluctuating part of the fluid dynamical fields with respect to the azimuthal angle, the radius in the transverse plane and rapidity. We examine how the time evolution of linear perturbations depends on the equation of state as well as on shear viscosity, bulk viscosity and heat conductivity for modes with different azimuthal, radial and rapidity wave numbers. Finally we discuss how this information is accessible to experiments in terms of the transverse and rapidity dependence of correlation functions for baryonic particles in high energy nuclear collisions.

  14. Seed regulations and local seed systems

    NARCIS (Netherlands)

    Louwaars, N.

    2000-01-01

    Seed regulations have been introduced in most countries based on the development of formal seed production. Concerns about seed quality and about the varietal identity of the seeds have commonly led to seed laws. However, formal regulations are often inappropriate for informal seed systems, which

  15. Colonization of citrus seed coats by 'Candidatus Liberibacter asiaticus': implications for seed transmission of the bacterium.

    Science.gov (United States)

    Hilf, Mark E

    2011-10-01

    Huanglongbing is an economically damaging disease of citrus associated with infection by 'Candidatus Liberibacter asiaticus'. Transmission of the organism via infection of seeds has not been demonstrated but is a concern since some citrus varieties, particularly those used as rootstocks in commercial plantings are propagated from seed. We compared the incidence of detection of 'Ca. Liberibacter asiaticus' DNA in individual fruit peduncles, seed coats, seeds, and in germinated seedlings from 'Sanguenelli' sweet orange and 'Conners' grapefruit fruits sampled from infected trees. Using real-time quantitative PCR (qPCR) we detected pathogen DNA in nucleic acid extracts of 36 and 100% of peduncles from 'Sanguenelli' and from 'Conners' fruits, respectively. We also detected pathogen DNA in extracts of 37 and 98% of seed coats and in 1.6 and 4% of extracts from the corresponding seeds of 'Sanguenelli' and 'Conners', respectively. Small amounts of pathogen DNA were detected in 10% of 'Sanguenelli' seedlings grown in the greenhouse, but in none of 204 extracts from 'Conners' seedlings. Pathogen DNA was detected in 4.9% and in 89% of seed coats peeled from seeds of 'Sanguenelli' and 'Conners' which were germinated on agar, and in 5% of 'Sanguenelli' but in none of 164 'Conners' seedlings which grew from these seeds on agar. No pathogen DNA was detected in 'Ridge Pineapple' tissue at 3 months post-grafting onto 'Sanguenelli' seedlings, even when pathogen DNA had been detected initially in the 'Sanguenelli' seedling. Though the apparent colonization of 'Conners' seeds was more extensive and nearly uniform compared with 'Sanguenelli' seeds, no pathogen DNA was detected in 'Conners' seedlings grown from these seeds. For either variety, no association was established between the presence of pathogen DNA in fruit peduncles and seed coats and in seedlings.

  16. Stepping responses to treadmill perturbations vary with severity of motor deficits in human SCI.

    Science.gov (United States)

    Chu, Virginia Way Tong; Hornby, T George; Schmit, Brian D

    2018-04-18

    In this study, we investigated the responses to tread perturbations during human stepping on a treadmill. Our approach was to test the effects of perturbations to a single leg using a split-belt treadmill in healthy participants and in participants with varying severity of spinal cord injury (SCI). We recruited 11 people with incomplete SCI and 5 noninjured participants. As participants walked on an instrumented treadmill, the belt on one side was stopped or accelerated briefly during mid to late stance. A majority of participants initiated an unnecessary swing when the treadmill was stopped in mid stance, although the likelihood of initiating a step was decreased in participants with more severe SCI. Accelerating or decelerating one belt of the treadmill during stance altered the characteristics of swing. We observed delayed swing initiation when the belt was decelerated (i.e. the hip was in a more flexed position at time of swing) and advanced swing initiation with acceleration (i.e. hip extended at swing initiation). Further, the timing and leg posture of heel strike appeared to remain constant, reflected by a sagittal plane hip angle at heel strike that remained the same regardless of the perturbation. In summary, our results supported the current understanding of the role of sensory feedback and central drive in the control of stepping in participants with incomplete SCI and noninjured participants. In particular, the observation of unnecessary swing during a stop perturbation highlights the interdependence of central and sensory drive in walking control.

  17. Constraints on the production of primordial magnetic seeds in pre-big bang cosmology

    Energy Technology Data Exchange (ETDEWEB)

    Gasperini, M., E-mail: gasperini@ba.infn.it [Dipartimento di Fisica, Università di Bari, Via G. Amendola 173, 70126 Bari (Italy)

    2017-06-01

    We study the amplification of the electromagnetic fluctuations, and the production of 'seeds' for the cosmic magnetic fields, in a class of string cosmology models whose scalar and tensor perturbations reproduce current observations and satisfy known phenomenological constraints. We find that the condition of efficient seeds production can be satisfied and compatible with all constraints only in a restricted region of parameter space, but we show that such a region has significant intersections with the portions of parameter space where the produced background of relic gravitational waves is strong enough to be detectable by aLIGO/Virgo and/or by eLISA.

  18. Water Productivity of Irrigated Rice under Transplanting, Wet Seeding and Dry Seeding Methods of Cultivation

    Directory of Open Access Journals (Sweden)

    Murali, NS.

    1997-01-01

    Full Text Available Water productivity (WP of irrigated lowland rice was determined during the 1994 dry (January to May and wet (August to December seasons on a heavy clay acid sulphate soil. Treatments consisted of three cultivation methods : transplanted rice, pregerminated seeds broadcasted on puddled soil (wet seeding and dry seeds broadcasted on unpuddled soil (dry seeding. In wet and dry seeded plots, continuous standing water condition was initiated 17 days after sowing. Total water requirement for rice production was highest in transplanted plots (755 mm in wet season and 1154 mm in dry season and was lowest in dry seeded plots (505 mm in wet season and 1040 mm in dry season. Dry seeding required no water for land preparation but transplanting and wet seeding methods required 18 - 20 % of total water requirement in dry season and 27 - 29 % in wet season. Total percolation was maximum (99 mm in wet season and 215 mm in dry season in dry seeding method and was minimum (62 mm in wet season and 94 mm in dry season in transplanting method. In dry and wet seeding methods, daily percolation gradually decreased with the age of the crop. Total seepage loss did not show any significant difference between the cultivation methods in the two seasons. Grain yield was not affected by the three cultivation methods in both seasons. Water productivity (the ratio between grain yield and total amount of water used in production was 3.5 - 4.1 kg ha-1 mm-1, 3.8 - 4.4 kg ha-1 mm-1 and 4.1 - 5.5 kg ha-1 mm-1 in transplanted, wet seeded and dry seeded rice, respectively. Labour requirement for land preparation and sowing was maximum in transplanted (219 - 226 man-hours ha-1 followed by wet (104 -112 man-hours ha-1 and dry seeded (94 - 99 man-hours ha-1 methods. However, in wet season extra labour (77 man-hours ha-1 was required for weeding after crop establishment in dry and wet seeding methods. Crop maturity was 20 days earlier in wet and dry seeding methods compared to

  19. Modularity and the spread of perturbations in complex dynamical systems.

    Science.gov (United States)

    Kolchinsky, Artemy; Gates, Alexander J; Rocha, Luis M

    2015-12-01

    We propose a method to decompose dynamical systems based on the idea that modules constrain the spread of perturbations. We find partitions of system variables that maximize "perturbation modularity," defined as the autocovariance of coarse-grained perturbed trajectories. The measure effectively separates the fast intramodular from the slow intermodular dynamics of perturbation spreading (in this respect, it is a generalization of the "Markov stability" method of network community detection). Our approach captures variation of modular organization across different system states, time scales, and in response to different kinds of perturbations: aspects of modularity which are all relevant to real-world dynamical systems. It offers a principled alternative to detecting communities in networks of statistical dependencies between system variables (e.g., "relevance networks" or "functional networks"). Using coupled logistic maps, we demonstrate that the method uncovers hierarchical modular organization planted in a system's coupling matrix. Additionally, in homogeneously coupled map lattices, it identifies the presence of self-organized modularity that depends on the initial state, dynamical parameters, and type of perturbations. Our approach offers a powerful tool for exploring the modular organization of complex dynamical systems.

  20. Evolution of perturbation in charge-varying dusty plasmas

    International Nuclear Information System (INIS)

    Popel, S.I.; Golub, A.P.; Losseva, T.V.; Bingham, R.; Benkadda, S.

    2001-01-01

    The nonstationary problem of the evolution of perturbation and its transformation into nonlinear wave structure in dusty plasmas is considered. For this purpose two one-dimensional models based on a set of fluid equations, Poisson's equation, and a charging equation for dust are developed. The first (simplified) model corresponds to the case [Popel et al., Phys. Plasmas 3, 4313 (1996)] when exact steady-state shock wave solutions can exist. This simplified model includes variable-charged dust grains, Boltzmann electrons, and inertial ions. The second (ionization source) model takes into account the variation of the ion density and the ion momentum dissipation due to dust particle charging as well as the source of plasma particles due to ionization process. The computational method for solving the set of equations which describe the evolution in time of a nonlinear structure in a charge-varying dusty plasma is developed. The case of the evolution of an intensive initial nonmoving region with a constant enhanced ion density is investigated on the basis of these two models. The consideration within the ionization source model is performed for the data of the laboratory experiment [Luo et al., Phys. Plasmas 6, 3455 (1999)]. It is shown that the ionization source model allows one to obtain shock structures as a result of evolution of an initial perturbation and to explain the experimental value of the width of the shock wave front. Comparison of the numerical data obtained on the basis of the ionization source model and the simplified model shows that the main characteristic features of the shock structure are the same for both models. Nevertheless, the ionization source model is much more sensitive to the form of the initial perturbation than the simplified model. The solution of the problem of the evolution of perturbation and its transformation into shock wave in charge-varying dusty plasmas opens up possibilities for description of the real phenomena like supernova

  1. An Initial Seed Selection Algorithm for K-means Clustering of Georeferenced Data to Improve Replicability of Cluster Assignments for Mapping Application

    OpenAIRE

    Khan, Fouad

    2016-01-01

    K-means is one of the most widely used clustering algorithms in various disciplines, especially for large datasets. However the method is known to be highly sensitive to initial seed selection of cluster centers. K-means++ has been proposed to overcome this problem and has been shown to have better accuracy and computational efficiency than k-means. In many clustering problems though -such as when classifying georeferenced data for mapping applications- standardization of clustering methodolo...

  2. Initial value problem for plasma oscillations

    International Nuclear Information System (INIS)

    Li, J.; Spies, G.O.

    1991-01-01

    The solution of the initial value problem for the linearized one-dimensional electron Vlasov--Poisson equations in a field-free homogeneous equilibrium is examined for small and for large ratios κ of Debye length and wavelength, assuming initial perturbing distribution functions varying on the same velocity scale as the equilibrium. Previously known approximations of the initial evolution (which, unlike the time-asymptotic one, does not depend on analyticity assumptions) are extended to longer times, and to arbitrary stable or unstable equilibria: In the quasifluid regime (small κ), the electric field, within an additive error O(κ 2 ), and independently of the initial data, performs an oscillation near the plasma frequency that corresponds to an eigenmode if it is unstable or marginal, but to an approximate eigenmode arising from the continuous spectrum otherwise. If other unstable or marginal modes are present, these influence only the time-asymptotic behavior because their amplitudes are O(κ 2 ) initially. In the ballistic regime (large κ), there are no instabilities and the perturbing density, now within an error O(κ -2 ), is the Fourier transform of the initial perturbing distribution function, thus following an arbitrary decay law that is independent of the equilibrium. The errors are shown to be time-independent, implying that either approximation is relevant at least until the perturbing density has essentially damped out. Hence the dominating damping mechanism (in the stable case) is Landau damping if κ much-lt 1, but ballistic particle mixing if κ much-gt 1

  3. Thieving rodents as substitute dispersers of megafaunal seeds

    Science.gov (United States)

    Jansen, Patrick A.; Hirsch, Ben T.; Emsens, Willem-Jan; Zamora-Gutierrez, Veronica; Wikelski, Martin; Kays, Roland

    2012-01-01

    The Neotropics have many plant species that seem to be adapted for seed dispersal by megafauna that went extinct in the late Pleistocene. Given the crucial importance of seed dispersal for plant persistence, it remains a mystery how these plants have survived more than 10,000 y without their mutualist dispersers. Here we present support for the hypothesis that secondary seed dispersal by scatter-hoarding rodents has facilitated the persistence of these large-seeded species. We used miniature radio transmitters to track the dispersal of reputedly megafaunal seeds by Central American agoutis, which scatter-hoard seeds in shallow caches in the soil throughout the forest. We found that seeds were initially cached at mostly short distances and then quickly dug up again. However, rather than eating the recovered seeds, agoutis continued to move and recache the seeds, up to 36 times. Agoutis dispersed an estimated 35% of seeds for >100 m. An estimated 14% of the cached seeds survived to the next year, when a new fruit crop became available to the rodents. Serial video-monitoring of cached seeds revealed that the stepwise dispersal was caused by agoutis repeatedly stealing and recaching each other’s buried seeds. Although previous studies suggest that rodents are poor dispersers, we demonstrate that communities of rodents can in fact provide highly effective long-distance seed dispersal. Our findings suggest that thieving scatter-hoarding rodents could substitute for extinct megafaunal seed dispersers of tropical large-seeded trees. PMID:22802644

  4. Germination and field survival of white-topped pitcher plant seeds

    Science.gov (United States)

    Kristina Connor; Hilliard Gibbs

    2012-01-01

    A study was initiated to determine longevity of white-topped pitcher plant (Sarracenia leucophylla, Raf.) seeds in the field and in cold storage. Thirty seed pods were harvested in August 2009 from plants located in Alabama 38 miles from the Gulf Coast. Of the 10,000+ seeds extracted from the pods, some were buried outside in screen-wire bags and...

  5. On a Shallow Water Equation Perturbed in Schwartz Class

    International Nuclear Information System (INIS)

    Zhu Xiang’ou

    2012-01-01

    We discuss the Camassa-Holm equation perturbed in Schwartz class around a suitable constant. This paper is concerned with the wave breaking mechanism for periodic case where two special classes of initial data were involved. The asymptotic behavior of solutions is also analyzed in the following sense: the corresponding solution to initial data with algebraic decay at infinity will retain this property at infinity in its lifespan.

  6. Seeding Event: Creating and Developing Spaces of Entrepreneurial Freedom

    Directory of Open Access Journals (Sweden)

    Gaëtan Mourmant

    2012-12-01

    Full Text Available This paper addresses the question of initiating, fostering and growing a vibrant economy by developing Spaces of Entrepreneurial Freedom (SoEF. Establishing and developing the SoEF is explained by a seeding event which is the core category of this grounded theory. In short, a seeding event leads to the patching of a potential, structural “hole”, which may prove valuable to an entrepreneurial network. Seeding events are started by an initiator who will recognize a network opportunity and exploit it. After event designing, the initiators implement the event through bold experimentation and using an adaptive structure. If the event is considered successful, the next stages are refining, growing, templating and finally replicating; these stages may occur one after the other or simultaneously. Through the development of SoEF, we suggest that entrepreneurs, governments, universities, large companies, and other players in the business world can improve the development of entrepreneurship at their respective levels.

  7. A Parameter Robust Method for Singularly Perturbed Delay Differential Equations

    Directory of Open Access Journals (Sweden)

    Erdogan Fevzi

    2010-01-01

    Full Text Available Uniform finite difference methods are constructed via nonstandard finite difference methods for the numerical solution of singularly perturbed quasilinear initial value problem for delay differential equations. A numerical method is constructed for this problem which involves the appropriate Bakhvalov meshes on each time subinterval. The method is shown to be uniformly convergent with respect to the perturbation parameter. A numerical example is solved using the presented method, and the computed result is compared with exact solution of the problem.

  8. Characteristics of Color Development in Seeds of Brown- and Yellow-Seeded Heading Chinese Cabbage and Molecular Analysis of Brsc, the Candidate Gene Controlling Seed Coat Color.

    Science.gov (United States)

    Ren, Yanjing; He, Qiong; Ma, Xiaomin; Zhang, Lugang

    2017-01-01

    The proanthocyanidin (PA) is the main flavonoids which affect the seed coat color in Brassica species. In this paper, characteristics of color development and accumulation of flavonoids were analyzed in the seeds of brown-seeded (B147) and yellow-seeded (B80) heading Chinese cabbage ( Brassica rapa L. ssp. Pekinensis ). It is found that the content of phenolic compounds in B147 were significantly more than that of B80 by using dimethylaminocinnamaldehyde (DMACA) staining and toluidine blue O (TBO) staining. In previous studies, the locus associated with seed coat color has been mapped. The results of whole genome re-sequencing showed that there are large fragment deletions variation in the mapping region between the brown-seeded parent '92S105' and the yellow-seeded parent '91-125.' Based on the B. rapa genome annotation information, the TRANSPARENT TESTA GLABRA 1 ( TTG1 ), is likely to be the candidate gene controlling seed coat color. A 94-base deletion was found in the 96th base downstream of the initiation codon in the TTG1 of yellow seed, thus, the termination codon TGA was occurred in the 297th base which makes the full length of TTG1 of yellow seed is 300 bp. Based on the differential sequences of TTG1 of brown and yellow seed, a functional marker, Brsc-yettg1, was developed to detect the variation of TTG1 . Quantitative real-time PCR analysis of BrTTG1 in different tissues showed that expression levels of BrTTG1 was not tissue-specific. During the whole seed development period, the expression of BrTTG1 in B147 was higher than that of B80. The expression levels of four structural genes, BrDFR, BrANS, BrANR1 , and BrANR2 in B147 were also higher than those in B80. The co-segregation molecular markers obtained in this report and TTG1 related information provide a basis for further understanding of the molecular mechanism of seed coat color in heading Chinese cabbage.

  9. Ecological patterns of seed microbiome diversity, transmission, and assembly.

    Science.gov (United States)

    Shade, Ashley; Jacques, Marie-Agnès; Barret, Matthieu

    2017-06-01

    Seeds are involved in the transmission of microorganisms from one plant generation to another and consequently act as the initial inoculum for the plant microbiota. The purpose of this mini-review is to provide an overview of current knowledge on the diversity, structure and role of the seed microbiota. The relative importance of the mode of transmission (vertical vs horizontal) of the microbial entities composing the seed microbiota as well as the potential connections existing between seed and other plant habitats such as the anthosphere and the spermosphere is discussed. Finally the governing processes (niche vs neutral) involved in the assembly and the dynamics of the seed microbiota are examined. Copyright © 2017. Published by Elsevier Ltd.

  10. Behaviour of scalar perturbations of a Reissner-Nordstroem black hole inside the event horizon

    International Nuclear Information System (INIS)

    McNamara, J.M.

    1978-01-01

    This paper considers general scalar perturbations of a Reissner-Nordstrom black hole and examines the qualitative behaviour of these perturbations in the region between and on the inner and outer horizons. Initial data are specified in terms of the ingoing radiation crossing the outer (event) horizon. The only essential restriction on these data is that the radiation should not die away too slowly on this horizon. The resultant perturbations are shown to be bounded and continuous. In particular, these properties hold for perturbations on the inner horizon. For certain types of scalar field (including the zero rest mass scalar field) perturbations vanish at the cross-over point on the inner horizon. (author)

  11. Imbibition of wheat seeds: Application of image analysis

    Science.gov (United States)

    Lev, Jakub; Blahovec, Jiří

    2017-10-01

    Image analysis is widely used for monitoring seeds during germination, and it is often the final phase of germination that is subjected to the greatest attention. However, the initial phase of germination (the so-called imbibition) also exhibits interesting behaviour. This work shows that image analysis has significant potential in the imbibition. Herein, a total of 120 seeds were analysed during germination tests, and information about seed size and shape was stored and analysed. It was found that the imbibition can be divided into two newly defined parts. The first one (`abrupt imbibition') consists mainly of the swelling of the seed embryo part and lasts approximately one hour. The second one, referred to as `main imbibition', consists mainly of spatial expansion caused by imbibition in the other parts of the seed. The results presented are supported by the development of seed cross area and shape parameters, and by direct observation.

  12. Relaxation periodic solutions of one singular perturbed system with delay

    Science.gov (United States)

    Kashchenko, A. A.

    2017-12-01

    In this paper, we consider a singularly perturbed system of two differential equations with delay, simulating two coupled oscillators with a nonlinear compactly supported feedback. We reduce studying nonlocal dynamics of initial system to studying dynamics of special finite-dimensional mappings: rough stable (unstable) cycles of these mappings correspond to exponentially orbitally stable (unstable) relaxation solutions of initial problem. We show that dynamics of initial model depends on coupling coefficient crucially. Multistability is proved.

  13. Dynamically constrained ensemble perturbations – application to tides on the West Florida Shelf

    Directory of Open Access Journals (Sweden)

    F. Lenartz

    2009-07-01

    Full Text Available A method is presented to create an ensemble of perturbations that satisfies linear dynamical constraints. A cost function is formulated defining the probability of each perturbation. It is shown that the perturbations created with this approach take the land-sea mask into account in a similar way as variational analysis techniques. The impact of the land-sea mask is illustrated with an idealized configuration of a barrier island. Perturbations with a spatially variable correlation length can be also created by this approach. The method is applied to a realistic configuration of the West Florida Shelf to create perturbations of the M2 tidal parameters for elevation and depth-averaged currents. The perturbations are weakly constrained to satisfy the linear shallow-water equations. Despite that the constraint is derived from an idealized assumption, it is shown that this approach is applicable to a non-linear and baroclinic model. The amplitude of spurious transient motions created by constrained perturbations of initial and boundary conditions is significantly lower compared to perturbing the variables independently or to using only the momentum equation to compute the velocity perturbations from the elevation.

  14. The onset condition of equatorial plasma bubbles - the role of seeding mechanism and growth condition

    Science.gov (United States)

    Kil, H.; Choi, J. M.; Kwak, Y. S.; Lee, W. K.; Park, J.

    2015-12-01

    We investigate the role of seeding mechanism and growth condition of perturbations in the creation of equatorial plasma bubbles by analyzing the C/NOFS and ROCSAT-1 satellite observations. The initial development times of bubbles were identified by manual processing of the data, and the periodic characteristics in the occurrence of bubbles were investigated using periodograms obtained from segments of bubble chains. Our preliminary results show that bubbles initiate at the time that the pre-reversal enhancement (PRE) ends. This time corresponds to the time that the F region reaches the highest altitude where the growth rate of the Rayleigh-Taylor (R-T) instability is large. The initial onset time of bubbles varies with season and longitude in accordance with the variation of the PRE ending time. Our investigation of the periodicity in the occurrence of bubbles (spacing between bubbles) shows that a dominant periodicity does not exist; the spacing between bubbles ranges from 100 km to over 1000 km. A pronounced periodicity occurs in some series of bubbles, but, in general, multiple periodicity co-exists. The initiation of bubbles at a specific local time but the absence of a preferential wave property in the occurrence of bubbles lead to the conclusion that the onset of bubbles is controlled by the growth condition of the R-T instability.

  15. (Cicer arietinum L.) seeds during germination by NMR spectroscopy

    African Journals Online (AJOL)

    Experiments were conducted to characterize the changes in water status during imbibition by nuclear magnetic resonance (NMR) spectroscopy in chickpea seeds exposed to static magnetic fields of 100 mT for 1 h. Water uptake during seed germination showed three phases with rapid initial hydration phase I, followed by ...

  16. Coherent and Incoherent Rogue Waves in Seeded Supercontinuum Generation

    DEFF Research Database (Denmark)

    Sørensen, Simon Toft; Larsen, Casper; Møller, Uffe Visbech

    2013-01-01

    The shot-to-shot stability of a supercontiuum (SC) can be controlled both in terms of coherence and intensity stability by modulating the input pulse with a weak seed [1-3]. In the long-pulse regime, the SC generation is initiated by noise-seeded modulation instability (MI), which breaks the pump...

  17. Time-dependent perturbation theory for nonequilibrium lattice models

    International Nuclear Information System (INIS)

    Jensen, I.; Dickman, R.

    1993-01-01

    The authors develop a time-dependent perturbation theory for nonequilibrium interacting particle systems. They focus on models such as the contact process which evolve via destruction and autocatalytic creation of particles. At a critical value of the destruction rate there is a continuous phase transition between an active steady state and the vacuum state, which is absorbing. They present several methods for deriving series for the evolution starting from a single seed particle, including expansions for the ultimate survival probability in the super- and subcritical regions, expansions for the average number of particles in the subcritical region, and short-time expansions. Algorithms for computer generation of the various expansions are presented. Rather long series (24 terms or more) and precise estimates of critical parameters are presented. 45 refs., 4 figs., 9 tabs

  18. A discrete homotopy perturbation method for non-linear Schrodinger equation

    Directory of Open Access Journals (Sweden)

    H. A. Wahab

    2015-12-01

    Full Text Available A general analysis is made by homotopy perturbation method while taking the advantages of the initial guess, appearance of the embedding parameter, different choices of the linear operator to the approximated solution to the non-linear Schrodinger equation. We are not dependent upon the Adomian polynomials and find the linear forms of the components without these calculations. The discretised forms of the nonlinear Schrodinger equation allow us whether to apply any numerical technique on the discritisation forms or proceed for perturbation solution of the problem. The discretised forms obtained by constructed homotopy provide the linear parts of the components of the solution series and hence a new discretised form is obtained. The general discretised form for the NLSE allows us to choose any initial guess and the solution in the closed form.

  19. Measurement of the stimulated thermal Rayleigh scattering instability

    International Nuclear Information System (INIS)

    Karr, T.J.; Rushford, M.C.; Murray, J.R.; Morris, J.R.

    1989-04-01

    Growth of perturbations due to stimulated thermal Rayleigh scattering was observed on a laser beam propagating in a 1 meter cell of CC14. Initial sinusoidal irradiance perturbations were seeded onto the laser leam, and their amplification in the cell was recorded by a near field camera. The perturbation growth rate is in agreement with analytical predictions of linearized propagation theory

  20. Effects of graphene on seed germination and seedling growth

    Energy Technology Data Exchange (ETDEWEB)

    Zhang, Ming; Gao, Bin, E-mail: bg55@ufl.edu [University of Florida, Department of Agricultural and Biological Engineering (United States); Chen, Jianjun [University of Florida, Department of Environmental Horticulture and Mid-Florida Research & Education Center (United States); Li, Yuncong [University of Florida, Soil and Water Science Department Tropical Research & Education Center (United States)

    2015-02-15

    The environmental impact of graphene has recently attracted great attention. In this work, we show that graphene at a low concentration affected tomato seed germination and seedling growth. Graphene-treated seeds germinated much faster than control seeds. Analytical results indicated that graphene penetrated seed husks. The penetration might break the husks to facilitate water uptake, resulting in faster germination and higher germination rates. At the stage of seedling growth, graphene was also able to penetrate root tip cells. Seedlings germinated from graphene-treated seeds had slightly lower biomass accumulation than the control, but exhibited significantly longer stems and roots than the control, which suggests that graphene, in contrast with other nanoparticles, had different effects on seedling growth. Taken together, our results imply that graphene played complicated roles in affecting the initial stage of seed germination and subsequent seedling growth.

  1. Oxygen dependency of germinating Brassica seeds

    Science.gov (United States)

    Park, Myoung Ryoul; Hasenstein, Karl H.

    2016-02-01

    Establishing plants in space, Moon or Mars requires adaptation to altered conditions, including reduced pressure and composition of atmospheres. To determine the oxygen requirements for seed germination, we imbibed Brassica rapa seeds under varying oxygen concentrations and profiled the transcription patterns of genes related to early metabolism such as starch degradation, glycolysis, and fermentation. We also analyzed the activity of lactate dehydrogenase (LDH) and alcohol dehydrogenase (ADH), and measured starch degradation. Partial oxygen pressure (pO2) greater than 10% resulted in normal germination (i.e., protrusion of radicle about 18 hours after imbibition) but lower pO2 delayed and reduced germination. Imbibition in an oxygen-free atmosphere for three days resulted in no germination but subsequent transfer to air initiated germination in 75% of the seeds and the root growth rate was transiently greater than in roots germinated under ambient pO2. In hypoxic seeds soluble sugars degraded faster but the content of starch after 24 h was higher than at ambient oxygen. Transcription of genes related to starch degradation, α-amylase (AMY) and Sucrose Synthase (SUS), was higher under ambient O2 than under hypoxia. Glycolysis and fermentation pathway-related genes, glucose phosphate isomerase (GPI), 6-phosphofructokinase (PFK), fructose 1,6-bisphosphate aldolase (ALD), glyceraldehyde-3-phosphate dehydrogenase (GAPDH), pyruvate decarboxylase (PDC), LDH, and ADH, were induced by low pO2. The activity of LDH and ADH was the highest in anoxic seeds. Germination under low O2 conditions initiated ethanolic fermentation. Therefore, sufficient oxygen availability is important for germination before photosynthesis provides necessary oxygen and the determination of an oxygen carrying capacity is important for uniform growth in space conditions.

  2. Gauge invariant perturbations of self-similar Lemaitre-Tolman-Bondi spacetime: Even parity modes with l≥2

    International Nuclear Information System (INIS)

    Waters, Thomas J.; Nolan, Brien C.

    2009-01-01

    In this paper we consider gauge invariant linear perturbations of the metric and matter tensors describing the self-similar Lemaitre-Tolman-Bondi (timelike dust) spacetime containing a naked singularity. We decompose the angular part of the perturbation in terms of spherical harmonics and perform a Mellin transform to reduce the perturbation equations to a set of ordinary differential equations with singular points. We fix initial data so the perturbation is finite on the axis and the past null cone of the singularity, and follow the perturbation modes up to the Cauchy horizon. There we argue that certain scalars formed from the modes of the perturbation remain finite, indicating linear stability of the Cauchy horizon.

  3. Conditions Affecting Shelf-Life of Inoculated Legume Seed

    Directory of Open Access Journals (Sweden)

    Greg Gemell

    2012-02-01

    Full Text Available Microbial inoculants are becoming more available as sustainable alternatives to fertilizers and other agrichemicals in broad-acre cropping. However, with the exception of legume inoculants little is understood about effective delivery and survival of the inoculum. Legume inoculants are applied to both seed and soil but seed inoculation is the most economical technique. Large quantities of pasture seed in Australia are inoculated by commercial seed coating companies, but the long-term survival of seed-applied inoculum is variable and monitoring of viability requires specialist microbiology skills and facilities. The aim of our research was to define optimum storage conditions for survival of rhizobia on legume seed and evaluate water activity as a means of monitoring shelf-life. The relationship between survival and water activity varied according to seed species, inoculum preparation, coating ingredients, initial water activity and time suggesting that storage conditions would need to be defined for each different combination. Although drying seeds after coating significantly reduced viable numbers of rhizobia, survival of rhizobia on dried commercially coated lucerne seed after 11 weeks was less variable than seeds that had not been dried. The highest numbers were maintained when seeds remained dry with water activities of between 0.47 and 0.38. The quality of inoculated seed could be improved by reducing the death rate of inoculum during preparation and providing optimum storage conditions for long-term survival.

  4. The influence of temperature dynamics and dynamic finite ion Larmor radius effects on seeded high amplitude plasma blobs

    DEFF Research Database (Denmark)

    Held, Magnus; Wiesenberger, M.; Madsen, Jens

    2016-01-01

    Thermal effects on the perpendicular convection of seeded pressure blobs in the scrape-off layer of magnetised fusion plasmas are investigated. Our numerical study is based on a four field full-F gyrofluid model, which entails the consistent description of high fluctuation amplitudes and dynamic...... finite Larmor radius effects. We find that the maximal radial blob velocity increases with the square root of the initial pressure perturbation and that a finite Larmor radius contributes to highly compact blob structures that propagate in the poloidal direction. An extensive parameter study reveals...... that a smooth transition to this compact blob regime occurs when the finite Larmor radius effect strength, defined by the ratio of the magnetic field aligned component of the ion diamagnetic to the E × B vorticity, exceeds unity. The maximal radial blob velocities agree excellently with the inertial velocity...

  5. A perturbative approach for enhancing the performance of time series forecasting.

    Science.gov (United States)

    de Mattos Neto, Paulo S G; Ferreira, Tiago A E; Lima, Aranildo R; Vasconcelos, Germano C; Cavalcanti, George D C

    2017-04-01

    This paper proposes a method to perform time series prediction based on perturbation theory. The approach is based on continuously adjusting an initial forecasting model to asymptotically approximate a desired time series model. First, a predictive model generates an initial forecasting for a time series. Second, a residual time series is calculated as the difference between the original time series and the initial forecasting. If that residual series is not white noise, then it can be used to improve the accuracy of the initial model and a new predictive model is adjusted using residual series. The whole process is repeated until convergence or the residual series becomes white noise. The output of the method is then given by summing up the outputs of all trained predictive models in a perturbative sense. To test the method, an experimental investigation was conducted on six real world time series. A comparison was made with six other methods experimented and ten other results found in the literature. Results show that not only the performance of the initial model is significantly improved but also the proposed method outperforms the other results previously published. Copyright © 2017 Elsevier Ltd. All rights reserved.

  6. Adaptation of reach-to-grasp movement in response to force perturbations.

    Science.gov (United States)

    Rand, M K; Shimansky, Y; Stelmach, G E; Bloedel, J R

    2004-01-01

    This study examined how reach-to-grasp movements are modified during adaptation to external force perturbations applied on the arm during reach. Specifically, we examined whether the organization of these movements was dependent upon the condition under which the perturbation was applied. In response to an auditory signal, all subjects were asked to reach for a vertical dowel, grasp it between the index finger and thumb, and lift it a short distance off the table. The subjects were instructed to do the task as fast as possible. The perturbation was an elastic load acting on the wrist at an angle of 105 deg lateral to the reaching direction. The condition was modified by changing the predictability with which the perturbation was applied in a given trial. After recording unperturbed control trials, perturbations were applied first on successive trials (predictable perturbations) and then were applied randomly (unpredictable perturbations). In the early predictable perturbation trials, reach path length became longer and reaching duration increased. As more predictable perturbations were applied, the reach path length gradually decreased and became similar to that of control trials. Reaching duration also decreased gradually as the subjects adapted by exerting force against the perturbation. In addition, the amplitude of peak grip aperture during arm transport initially increased in response to repeated perturbations. During the course of learning, it reached its maximum and thereafter slightly decreased. However, it did not return to the normal level. The subjects also adapted to the unpredictable perturbations through changes in both arm transport and grasping components, indicating that they can compensate even when the occurrence of the perturbation cannot be predicted during the inter-trial interval. Throughout random perturbation trials, large grip aperture values were observed, suggesting that a conservative aperture level is set regardless of whether the

  7. Role of magnetic flux perturbations in confinement bifurcations in TUMAN-3M

    International Nuclear Information System (INIS)

    Lebedev, S.V.; Andreiko, M.V.; Askinazi, L.G.

    2003-01-01

    Poloidal magnetic flux variations in the small tokamak TUMAN-3M allowed observation of transitions between different confinement modes. The possibility of switching on/off the ohmic H-mode by edge poloidal magnetic flux perturbations has been found. The flux perturbations were created by fast current ramp up/down or by magnetic compression/decompression produced by fast increase/decrease in the toroidal magnetic field. It was found that positive flux perturbations (current ramp-up and magnetic compression scenarios) are useful means of H-mode triggering. If a negative flux perturbation (current ramp-down or magnetic decompression) is applied, the H-mode terminated. Various mechanisms involved in the L-H and H-L transition physics in the flux perturbation experiments were analyzed. The experimental observations of the transitions between confinement modes might be understood in terms of the model of a sheared radial electric field generation, which takes into account the electron Ware drift in a perturbed longitudinal electric field. Another scenario of improved confinement was observed in the initial phase of an ohmic discharge, when change in the poloidal flux is associated with current ramp-up. Variation of the rates of current ramp-up and working gas puffing in the beginning of a discharge resulted in a fast increase in the electron temperature near the axis. The increase correlates with low m/n MHD mode growth. The observed core electron confinement improvement is apparently connected with the rate of current ramp. Deviation from the optimal rate results in disappearance of the improvement. The role of magnetic shear profile and rational magnetic surfaces in the core electron confinement improvement in the initial phase of ohmic discharges is discussed. (author)

  8. Change in radiosensitivity of seeds depending on their humidity data and methods of moistening

    International Nuclear Information System (INIS)

    Savin, B.N.; Labrada, A.R.

    1980-01-01

    Investigated was the change in readiosensitivity of maize seeds depending on their humidity, method of moistening and initial humidity before moistening. Maize seeds of Krasnodarskaya 303 TV breed were irradiated with γ-rays. It was shown that seeds of the same humidity had different radiosensitivity depending on the method of moistening. When moistening seeds in water, they had the highest radiostability at 20-24% humidity but when moistening them in exsiccator, this index was the highest at 15% humidity. Along with the method of moistening initial humidity before moistening also effected the radiosensitivity. The necessity to take this factor into account during presowing irradiation was noted

  9. Use of seeds to control precipitation of calcium carbonate and determination of seed nature.

    Science.gov (United States)

    Donnet, Marcel; Bowen, Paul; Jongen, Nathalie; Lemaître, Jacques; Hofmann, Heinrich

    2005-01-04

    Understanding and controlling precipitation reactions is a major challenge for industrial crystallization. Calcium carbonate is a widely studied system: more than 3000 papers have been devoted to the subject over the past 10 years. The first step of the precipitation of calcium carbonate, from relatively concentrated solutions (0.01 mol/L), involves the formation of an initial gel phase which later transforms into calcite, vaterite, or a mixture of both phases. Our work aimed at controlling this first step. Nanosized seeds (8 nm), formed in situ, were used in order to control the often chaotic nucleation step which normally leads to poor phase selection and broad particle size distributions. Seeding has often been used to avoid spontaneous nucleation in metastable solutions for growth mechanism investigations of single-crystal calcium carbonate. Here the ability of a seeding method to control the precipitation reaction evolution even in the case of high supersaturation is demonstrated. The seeds and the presence of a polymeric additive (poly(acrylic acid)) allow the control of the precipitated polymorph and the specific surface area, while maintaining a narrow particle size distribution in the submicron range. Direct characterization methods did not succeed in identifying these nanoseeds; indirect methods using solubility calculations are used to demonstrate their existence and quantify size and number density of the nanosized seeds.

  10. Use of bioactivator, biostimulant and complex of nutrients in soybean seeds

    Directory of Open Access Journals (Sweden)

    José Adolfo Binsfeld

    2014-03-01

    Full Text Available New discoveries have stimulated the use of different substances with physiologic effects, in order to develop agricultural crops. Thus, this study aimed at evaluating seeds treated with biostimulant, bioactivator and nutrients, in the initial development of soybean seeds. Two lots of seeds (high and low vigor, BMX Potência RR cultivar were used. The products tested were an insecticide with bioactivator effect, a plant growth regulator with biostimulant effect, a complex of nutrients and a control. Under laboratory conditions, the parameters water content, germination, first germination counting, accelerated aging, cold test, length and dry matter weight of seedlings were evaluated. Under greenhouse conditions, evaluations included emergence, emergence speed index, length and dry matter weight of seedlings. The efficiency of the products tested was affected by the seed physiologic quality, with a more pronounced effect for the products in high vigor lots. In general, the treatment with best results for initial performance was the complex of nutrients, followed by the plant growth regulator with biostimulant effect. The bioactivator had negative effect on seeds germination and seedling development.

  11. Irradiation effect on the seed vigor, SOD activity and MDA content in germinating seeds of yellow-seeded and black-seeded rape seed (Brassica napus L.)

    International Nuclear Information System (INIS)

    Han Jixiang; Hu Danhong; Liu Houli

    1993-01-01

    Seeds of a set of near-isogenic lines (Brassica napus L.) with different seed coat color from yellow to black were irradiated by 60 Co γ-rays of 150 krad. Seed vigor, superoxide dismutase (SOD) and malondialdehyde (MDA) in germinating seeds were analysed. In these characters, no significant difference between yellow-seeded lines (YLs) and black-seeded lines (BLs) showed before irradiation. But after irradiation, SOD activity in YLs was lower than that in BLs. While MDA content in YLs was obviously higher that that in DLs. As a result of irradiation, seed vigor of YLs was lower than that in BLs. these results indicated that the irradiation resistance of rape seed was related to the level of SOD as well as protective structure or substances in seed coat and that the radiosensitivity of YLs was higher than that of DLs

  12. Understanding Theoretical Uncertainties in Perturbative QCD Computations

    DEFF Research Database (Denmark)

    Jenniches, Laura Katharina

    effective field theories and perturbative QCD to predict the effect of New Physics on measurements at the LHC and at other future colliders. We use heavy-quark, heavy-scalar and soft-collinear effective theory to calculate a three-body cascade decay at NLO QCD in the expansion-by-regions formalism...... discuss an extension of the Cacciari-Houdeau approach to observables with hadrons in the initial state....

  13. Perturbed effects at radiation physics

    International Nuclear Information System (INIS)

    Külahcı, Fatih; Şen, Zekâi

    2013-01-01

    Perturbation methodology is applied in order to assess the linear attenuation coefficient, mass attenuation coefficient and cross-section behavior with random components in the basic variables such as the radiation amounts frequently used in the radiation physics and chemistry. Additionally, layer attenuation coefficient (LAC) and perturbed LAC (PLAC) are proposed for different contact materials. Perturbation methodology provides opportunity to obtain results with random deviations from the average behavior of each variable that enters the whole mathematical expression. The basic photon intensity variation expression as the inverse exponential power law (as Beer–Lambert's law) is adopted for perturbation method exposition. Perturbed results are presented not only in terms of the mean but additionally the standard deviation and the correlation coefficients. Such perturbation expressions provide one to assess small random variability in basic variables. - Highlights: • Perturbation methodology is applied to Radiation Physics. • Layer attenuation coefficient (LAC) and perturbed LAC are proposed for contact materials. • Perturbed linear attenuation coefficient is proposed. • Perturbed mass attenuation coefficient (PMAC) is proposed. • Perturbed cross-section is proposed

  14. Effects of core perturbations on the structure of the sun

    International Nuclear Information System (INIS)

    Sweigart, A.V.

    1983-01-01

    A number of numerical experiments have been carried out in order to investigate the sensivity of the solar luminosity and radius to perturbations within the radiative core. In these experiments the core was perturbed by suddenly mixing various parts of the composition profile during evolutionary sequences for the present Sun. The hydrostatic readjustment caused by these ''mixing events'' induced an immediate change in the surface luminosity and radius on both the hydrodynamic time scale (approx.15 minutes) and the thermal time scale of the superadiabatic layers (approx.1 day). The subsequent evolution of the luminosity and radius perturbations was followed for 5 x 10 5 yr after each mixing event. The time-dependent behavior of these perturbations was found to depend on where the mixing event occurred. In all cases, however, the ratio W(t) = Δ log R/Δ log L had an initial value of 0.71 and showed only a mild time dependence during the first several thousand years. Two other relationships between the luminosity and radius perturbations are also discussed. One of these, V(t) = (d log R/dd)/(d log L/dt), has a fairly constant value of 0.3 +- 0.1. Both perturbations in the mixing-length ratio α and perturbations in the magnetic pressure within the solar convective envelope yield the same value for V/(t). During the normal unperturbed evolution of the present Sun, V(t) = 0.4. Our results show that core perturbations such as the present mixing events cannot explain the decrease in the solar radius indicated by the solar eclipse data between 1925 and 1980

  15. Enzyme activity and reserve mobilization during Macaw palm ( Acrocomia aculeata seed germination

    Directory of Open Access Journals (Sweden)

    Elisa Monteze Bicalho

    2016-01-01

    Full Text Available ABSTRACT Reserve mobilization in seeds occurs after visible germination, which is marked by the protrusion of the radicle or cotyledonary petiole, as in species of Arecaceae. Acrocomia aculeata (macaw palm, usually produces hard seeds whose endosperm has mannan-rich cell walls. We investigated the composition of storage compounds in macaw palm seed and the roles of two enzymes (endo-β-mannanase, α-galactosidase during and after germination. The seeds were firstly submitted to pre-established protocol to overcome dormancy and promote germination. Enzyme activity in both embryo and endosperm were assayed from the initiation of germinative activities until leaf sheath appearance, and the status of seed structures and reserve compounds were evaluated. Protein content of the embryo decreased with the initiation of imbibition while the lipid content began decreasing six days after removal of the operculum. Increases in enzyme activity and starch content were both observed after visible germination. We suggest that endo-β-mannanase and α-galactosidase become active immediately at germination, facilitating haustorium expansion and providing carbohydrates for initial seedling development. Protein is the first storage compound mobilized during early imbibition, and the observed increase in the starch content of the haustorium was related to lipid degradation in that organ and mannan degradation in the adjacent endosperm.

  16. Tangent Orbital Rendezvous Using Linear Relative Motion with J2 Perturbations

    Directory of Open Access Journals (Sweden)

    Gang Zhang

    2013-01-01

    Full Text Available The tangent-impulse coplanar orbit rendezvous problem is studied based on the linear relative motion for J2-perturbed elliptic orbits. There are three cases: (1 only the first impulse is tangent; (2 only the second impulse is tangent; (3 both impulses are tangent. For a given initial impulse point, the first two problems can be transformed into finding all roots of a single variable function about the transfer time, which can be done by the secant method. The bitangent rendezvous problem requires the same solution for the first two problems. By considering the initial coasting time, the bitangent rendezvous solution is obtained with a difference function. A numerical example for two coplanar elliptic orbits with J2 perturbations is given to verify the efficiency of these proposed techniques.

  17. Organic leek seed production - securing seed quality

    DEFF Research Database (Denmark)

    Deleuran, Lise Christina; Boelt, Birte

    2011-01-01

    To maintain integrity in organic farming, availability of organically produced GM-free seed of varieties adapted to organic production systems is of vital impor-tance. Despite recent achievements, organic seed supply for a number of vegetable species is insufficient. Still, in many countries...... seeds. Tunnel production is a means of securing seed of high genetic purity and quality, and organic leek (Allium porrum L.) seed production was tested in tunnels in Denmark. The present trial focused on steckling size and in all years large stecklings had a positive effect on both seed yield...

  18. Organic Leek Seed Production - Securing Seed Quality

    DEFF Research Database (Denmark)

    Deleuran, L C; Boelt, B

    2011-01-01

    To maintain integrity in organic farming, availability of organically produced GM-free seed of varieties adapted to organic production systems is of vital impor-tance. Despite recent achievements, organic seed supply for a number of vegetable species is insufficient. Still, in many countries...... seeds. Tunnel production is a means of securing seed of high genetic purity and quality, and organic leek (Allium porrum L.) seed production was tested in tunnels in Denmark. The present trial focused on steckling size and in all years large stecklings had a positive effect on both seed yield...

  19. Perturbative anyon gas

    International Nuclear Information System (INIS)

    Dasnieres de Veigy, A.; Ouvry, S.; Paris-6 Univ., 75

    1992-06-01

    The problem of the statistical mechanics of an anyon gas is addressed. A perturbative analysis in the anyonic coupling constant α is reviewed, and the thermodynamical potential is computed at first and second order. An adequate second quantized formalism (field theory at finite temperature) is proposed. At first order in perturbation theory, the results are strikingly simple: only the second virial coefficient close to bosonic statistics is corrected. At second order, however, the complexity of the anyon model appears. One can compute exactly the perturbative correction to each cluster coefficient. However, and contrary to first order, a closed expression for the equation of state seems out of reach. As an illustration, the perturbative expressions of a 3 , a 4 , a 5 and a 6 are given at second order. Finally, using the same formalism, the equation of state of an anyon gas in a constant magnetic field is analyzed at first order in perturbation theory. (K.A.) 16 refs.; 3 figs.; 7 tabs

  20. Objective quantification of perturbations produced with a piecewise PV inversion technique

    Directory of Open Access Journals (Sweden)

    L. Fita

    2007-11-01

    Full Text Available PV inversion techniques have been widely used in numerical studies of severe weather cases. These techniques can be applied as a way to study the sensitivity of the responsible meteorological system to changes in the initial conditions of the simulations. Dynamical effects of a collection of atmospheric features involved in the evolution of the system can be isolated. However, aspects, such as the definition of the atmospheric features or the amount of change in the initial conditions, are largely case-dependent and/or subjectively defined. An objective way to calculate the modification of the initial fields is proposed to alleviate this problem. The perturbations are quantified as the mean absolute variations of the total energy between the original and modified fields, and an unique energy variation value is fixed for all the perturbations derived from different PV anomalies. Thus, PV features of different dimensions and characteristics introduce the same net modification of the initial conditions from an energetic point of view. The devised quantification method is applied to study the high impact weather case of 9–11 November 2001 in the Western Mediterranean basin, when a deep and strong cyclone was formed. On the Balearic Islands 4 people died, and sustained winds of 30 ms−1 and precipitation higher than 200 mm/24 h were recorded. Moreover, 700 people died in Algiers during the first phase of the event. The sensitivities to perturbations in the initial conditions of a deep upper level trough, the anticyclonic system related to the North Atlantic high and the surface thermal anomaly related to the baroclinicity of the environment are determined. Results reveal a high influence of the upper level trough and the surface thermal anomaly and a minor role of the North Atlantic high during the genesis of the cyclone.

  1. Empty seeds are not always bad: simultaneous effect of seed emptiness and masting on animal seed predation.

    Directory of Open Access Journals (Sweden)

    Ramón Perea

    Full Text Available Seed masting and production of empty seeds have often been considered independently as different strategies to reduce seed predation by animals. Here, we integrate both phenomena within the whole assemblage of seed predators (both pre and post-dispersal and in two contrasting microsites (open vs. sheltered to improve our understanding of the factors controlling seed predation in a wind-dispersed tree (Ulmus laevis. In years with larger crop sizes more avian seed predators were attracted with an increase in the proportion of full seeds predated on the ground. However, for abundant crops, the presence of empty seeds decreased the proportion of full seeds predated. Empty seeds remained for a very long period in the tree, making location of full seeds more difficult for pre-dispersal predators and expanding the overall seed drop period at a very low cost (in dry biomass and allocation of C, N and P. Parthenocarpy (non-fertilized seeds was the main cause of seed emptiness whereas seed abortion was produced in low quantity. These aborted seeds fell prematurely and, thus, could not work as deceptive seeds. A proportion of 50% empty seeds significantly reduced ground seed predation by 26%. However, a high rate of parthenocarpy (beyond 50% empty seeds did not significantly reduce seed predation in comparison to 50% empty seeds. We also found a high variability and unpredictability in the production of empty seeds, both at tree and population level, making predator deception more effective. Open areas were especially important to facilitate seed survival since rodents (the main post-dispersal predators consumed seeds mostly under shrub cover. In elm trees parthenocarpy is a common event that might work as an adaptive strategy to reduce seed predation. Masting per se did not apparently reduce the overall proportion of seeds predated in this wind-dispersed tree, but kept great numbers of seeds unconsumed.

  2. Chemical, morphological and functional properties of Brazilian jackfruit (Artocarpus heterophyllus L.) seeds starch.

    Science.gov (United States)

    Madruga, Marta Suely; de Albuquerque, Fabíola Samara Medeiros; Silva, Izis Rafaela Alves; do Amaral, Deborah Silva; Magnani, Marciane; Queiroga Neto, Vicente

    2014-01-15

    Starches used in food industry are extracted from roots, tubers and cereals. Seeds of jackfruit are abundant and contain high amounts of starch. They are discarded during the fruit processing or consumption and can be an alternative source of starch. The starch was extract from the jackfruit seeds and characterised to chemical, morphological and functional properties. Soft and hard jackfruit seeds showed starch content of 92.8% and 94.5%, respectively. Starch granules showed round and bell shape and some irregular cuts on their surface with type-A crystallinity pattern, similar to cereals starches. The swelling power and solubility of jackfruit starch increased with increasing temperature, showing opaque pastes. The soft seeds starch showed initial and final gelatinisation temperature of 36°C and 56°C, respectively; while hard seeds starch presented initial gelatinisation at 40°C and final at 61°C. These results suggest that the Brazilian jackfruit seeds starches could be used in food products. Copyright © 2013 Elsevier Ltd. All rights reserved.

  3. A Homotopy-Perturbation analysis of the non-linear contaminant ...

    African Journals Online (AJOL)

    In this research work, a Homotopy-perturbation analysis of a non –linear contaminant flow equation with an initial continuous point source is provided. The equation is characterized by advection, diffusion and adsorption. We assume that the adsorption term is modeled by Freudlich Isotherm. We provide an approximation of ...

  4. Seasonal pattern of seed dormancy in parthenium hysterophorus L

    International Nuclear Information System (INIS)

    Arshad Javaid, A.; Shafique, S.; Shafique, S.

    2010-01-01

    Earlier non-conclusive results have been reported on the initial dormancy status of parthenium (Parthenium hysterophorus L.) seeds. The present study reports the seasonal dormancy pattern of parthenium in Lahore, Pakistan where there are four distinct seasons viz. summer, autumn, winter and spring in a year. Mature parthenium seeds were collected on the last day of each month from January to December 2006 and investigations for their germination percentage and rate of germination were started on the next day. Parthenium seeds collected during coldest months of January and December showed highest germination of 100% with germination rate of 33.3% per day. Conversely, seeds collected in summer months of April to September exhibited lowest germination of 0-7% and germination rate of 0-1.75% per day. Seeds collected in rest of the months showed variable final germination percentage and germination rate ranging from 30-97% and 3.8-17.4%, respectively. Both the final germination and germination rate showed a highly significant negative correlation with the solar radiation and environmental temperature during the seed development period. The present study concludes that dormancy in parthenium seeds depends upon the temperature and solar radiation during the seed development period. (author)

  5. Can superhorizon cosmological perturbations explain the acceleration of the universe?

    International Nuclear Information System (INIS)

    Hirata, Christopher M.; Seljak, Uros

    2005-01-01

    We investigate the recent suggestions by Barausse et al. and Kolb et al. that the acceleration of the universe could be explained by large superhorizon fluctuations generated by inflation. We show that no acceleration can be produced by this mechanism. We begin by showing how the application of Raychaudhuri equation to inhomogeneous cosmologies results in several 'no go' theorems for accelerated expansion. Next we derive an exact solution for a specific case of initial perturbations, for which application of the Kolb et al. expressions leads to an acceleration, while the exact solution reveals that no acceleration is present. We show that the discrepancy can be traced to higher-order terms that were dropped in the Kolb et al. analysis. We proceed with the analysis of initial value formulation of general relativity to argue that causality severely limits what observable effects can be derived from superhorizon perturbations. By constructing a Riemann normal coordinate system on initial slice we show that no infrared divergence terms arise in this coordinate system. Thus any divergences found previously can be eliminated by a local rescaling of coordinates and are unobservable. We perform an explicit analysis of the variance of the deceleration parameter for the case of single-field inflation using usual coordinates and show that the infrared-divergent terms found by Barausse et al. and Kolb et al. cancel against several additional terms not considered in their analysis. Finally, we argue that introducing isocurvature perturbations does not alter our conclusion that the accelerating expansion of the universe cannot be explained by superhorizon modes

  6. Neoclassical tearing mode seeding by coupling with infernal modes in low-shear tokamaks

    Science.gov (United States)

    Kleiner, A.; Graves, J. P.; Brunetti, D.; Cooper, W. A.; Halpern, F. D.; Luciani, J.-F.; Lütjens, H.

    2016-09-01

    A numerical and an analytical study of the triggering of resistive MHD modes in tokamak plasmas with low magnetic shear core is presented. Flat q profiles give rise to fast growing pressure driven MHD modes, such as infernal modes. It has been shown that infernal modes drive fast growing islands on neighbouring rational surfaces. Numerical simulations of such instabilities in a MAST-like configuration are performed with the initial value stability code XTOR-2F in the resistive frame. The evolution of magnetic islands are computed from XTOR-2F simulations and an analytical model is developed based on Rutherford’s theory in combination with a model of resistive infernal modes. The parameter {{Δ }\\prime} is extended from the linear phase to the non-linear phase. Additionally, the destabilising contribution due to a helically perturbed bootstrap current is considered. Comparing the numerical XTOR-2F simulations to the model, we find that coupling has a strong destabilising effect on (neoclassical) tearing modes and is able to seed 2/1 magnetic islands in situations when the standard NTM theory predicts stability.

  7. Germinant size of jack pine in relation to seed size and geographic origin

    Science.gov (United States)

    C.W. Yeatman

    1966-01-01

    The initial size of conifer seedlings is closely related to seed size (Hadders 1963), and seed size is a maternal characteristic that is highly subject to environmental modification (Mergen et al. 1964; Righter 1945). The effect of seed weight must be accounted for in critical studies of seedlings which attempt to attribute differences in growth to specific genetic or...

  8. A Study of Single- and Double-Averaged Second-Order Models to Evaluate Third-Body Perturbation Considering Elliptic Orbits for the Perturbing Body

    Directory of Open Access Journals (Sweden)

    R. C. Domingos

    2013-01-01

    Full Text Available The equations for the variations of the Keplerian elements of the orbit of a spacecraft perturbed by a third body are developed using a single average over the motion of the spacecraft, considering an elliptic orbit for the disturbing body. A comparison is made between this approach and the more used double averaged technique, as well as with the full elliptic restricted three-body problem. The disturbing function is expanded in Legendre polynomials up to the second order in both cases. The equations of motion are obtained from the planetary equations, and several numerical simulations are made to show the evolution of the orbit of the spacecraft. Some characteristics known from the circular perturbing body are studied: circular, elliptic equatorial, and frozen orbits. Different initial eccentricities for the perturbed body are considered, since the effect of this variable is one of the goals of the present study. The results show the impact of this parameter as well as the differences between both models compared to the full elliptic restricted three-body problem. Regions below, near, and above the critical angle of the third-body perturbation are considered, as well as different altitudes for the orbit of the spacecraft.

  9. Effect of Electron Seeding on Experimentally Measured Multipactor Discharge Threshold

    Science.gov (United States)

    Noland, Jonathan; Graves, Timothy; Lemon, Colby; Looper, Mark; Farkas, Alex

    2012-10-01

    Multipactor is a vacuum phenomenon in which electrons, moving in resonance with an externally applied electric field, impact material surfaces. If the number of secondary electrons created per primary electron impact averages more than unity, the resonant interaction can lead to an electron avalanche. Multipactor is a generally undesirable phenomenon, as it can cause local heating, absorb power, or cause detuning of RF circuits. In order to increase the probability of multipactor initiation, test facilities often employ various seeding sources such as radioactive sources (Cesium 137, Strontium 90), electron guns, or photon sources. Even with these sources, the voltage for multipactor initiation is not certain as parameters such as material type, RF pulse length, and device wall thickness can all affect seed electron flux and energy in critical gap regions, and hence the measured voltage threshold. This study investigates the effects of seed electron source type (e.g., photons versus beta particles), material type, gap size, and RF pulse length variation on multipactor threshold. In addition to the experimental work, GEANT4 simulations will be used to estimate the production rate of low energy electrons (< 5 keV) by high energy electrons and photons. A comparison of the experimental fluxes to the typical energetic photon and particle fluxes experienced by spacecraft in various orbits will also be made. Initial results indicate that for a simple, parallel plate device made of aluminum, there is no threshold variation (with seed electrons versus with no seed electrons) under continuous-wave RF exposure.

  10. Analysis of interspecies physicochemical variation of grain legume seeds

    Science.gov (United States)

    Rybiński, Wojciech; Rusinek, Robert; Szot, Bogusław; Bocianowski, Jan; Starzycki, Michał

    2014-10-01

    The paper presents an attempt to assess the reaction of seeds to mechanical loads taking into account their geometry expressed as seed thickness and 1000 seed weight. The initial material comprised 33 genotypes of grain legume plants and included cultivars registered in the country and breeding lines that are subject to pre-registration trials. The analysis of variance revealed significant diversity of the cultivars and lines of the species studied in terms of each of the analysed trait. The highest weight of 1000 seeds were obtained for white lupine seeds and peas, the lowest for andean lupine seeds. The maximum deformation and energy were obtained for white lupine seeds, the lowest for pea seeds, the maximum force and module the lowest values were determined for narrow-leafed lupine and pea. The highest values of protein were obtained for andean and yellow lupine, a fat content for andean and white lupine. The fatty acid profile as much as 70% or more were linoleic and oleic acids. Against the background of all the species are distinguished by white lupine seeds with a high content of oleic acid and the lowest of linoleic acid, for yellow lupine were obtained the inverse ratio of the two acids.

  11. Perturbative Gaussianizing transforms for cosmological fields

    Science.gov (United States)

    Hall, Alex; Mead, Alexander

    2018-01-01

    Constraints on cosmological parameters from large-scale structure have traditionally been obtained from two-point statistics. However, non-linear structure formation renders these statistics insufficient in capturing the full information content available, necessitating the measurement of higher order moments to recover information which would otherwise be lost. We construct quantities based on non-linear and non-local transformations of weakly non-Gaussian fields that Gaussianize the full multivariate distribution at a given order in perturbation theory. Our approach does not require a model of the fields themselves and takes as input only the first few polyspectra, which could be modelled or measured from simulations or data, making our method particularly suited to observables lacking a robust perturbative description such as the weak-lensing shear. We apply our method to simulated density fields, finding a significantly reduced bispectrum and an enhanced correlation with the initial field. We demonstrate that our method reconstructs a large proportion of the linear baryon acoustic oscillations, improving the information content over the raw field by 35 per cent. We apply the transform to toy 21 cm intensity maps, showing that our method still performs well in the presence of complications such as redshift-space distortions, beam smoothing, pixel noise and foreground subtraction. We discuss how this method might provide a route to constructing a perturbative model of the fully non-Gaussian multivariate likelihood function.

  12. Seed-borne pathogens and electrical conductivity of soybean seeds

    Directory of Open Access Journals (Sweden)

    Adriana Luiza Wain-Tassi

    2012-02-01

    Full Text Available Adequate procedures to evaluate seed vigor are important. Regarding the electrical conductivity test (EC, the interference in the test results caused by seed-borne pathogens has not been clarified. This research was carried out to study the influence of Phomopsis sojae (Leh. and Colletotrichum dematium (Pers. ex Fr. Grove var. truncata (Schw. Arx. fungi on EC results. Soybean seeds (Glycine max L. were inoculated with those fungi using potato, agar and dextrose (PDA medium with manitol (-1.0 MPa and incubated for 20 h at 25 °C. The colony diameter, index of mycelial growth, seed water content, occurrence of seed-borne pathogens, physiological potential of the seeds, measured by germination and vigor tests (seed germination index, cold test, accelerated aging and electrical conductivity, and seedling field emergence were determined. The contents of K+, Ca2+, and Mg2+ in the seed and in the soaking solution were also determined. A complete 2 × 4 factorial design with two seed sizes (5.5 and 6.5 mm and four treatments (control, seeds incubated without fungi, seeds incubated with Phomopsis and seeds incubated with Colletotrichum were used with eight (5.5 mm large seeds and six (6.5 mm large seeds replications. All seeds submitted to PDA medium had their germination reduced in comparison to the control seeds. This reduction was also observed when seed vigor and leached ions were considered. The presence of Phomopsis sojae fungus in soybean seed samples submitted to the EC test may be the cause of misleading results.

  13. Developments in perturbation theory

    International Nuclear Information System (INIS)

    Greenspan, E.

    1976-01-01

    Included are sections dealing with perturbation expressions for reactivity, methods for the calculation of perturbed fluxes, integral transport theory formulations for reactivity, generalized perturbation theory, sensitivity and optimization studies, multigroup calculations of bilinear functionals, and solution of inhomogeneous Boltzmann equations with singular operators

  14. PerturbationAnalyzer: a tool for investigating the effects of concentration perturbation on protein interaction networks.

    Science.gov (United States)

    Li, Fei; Li, Peng; Xu, Wenjian; Peng, Yuxing; Bo, Xiaochen; Wang, Shengqi

    2010-01-15

    The propagation of perturbations in protein concentration through a protein interaction network (PIN) can shed light on network dynamics and function. In order to facilitate this type of study, PerturbationAnalyzer, which is an open source plugin for Cytoscape, has been developed. PerturbationAnalyzer can be used in manual mode for simulating user-defined perturbations, as well as in batch mode for evaluating network robustness and identifying significant proteins that cause large propagation effects in the PINs when their concentrations are perturbed. Results from PerturbationAnalyzer can be represented in an intuitive and customizable way and can also be exported for further exploration. PerturbationAnalyzer has great potential in mining the design principles of protein networks, and may be a useful tool for identifying drug targets. PerturbationAnalyzer can be accessed from the Cytoscape web site http://www.cytoscape.org/plugins/index.php or http://biotech.bmi.ac.cn/PerturbationAnalyzer. Supplementary data are available at Bioinformatics online.

  15. Creation and perturbation of planar networks of chemical oscillators

    Science.gov (United States)

    Tompkins, Nathan; Cambria, Matthew Carl; Wang, Adam L.; Heymann, Michael; Fraden, Seth

    2015-01-01

    Methods for creating custom planar networks of diffusively coupled chemical oscillators and perturbing individual oscillators within the network are presented. The oscillators consist of the Belousov-Zhabotinsky (BZ) reaction contained in an emulsion. Networks of drops of the BZ reaction are created with either Dirichlet (constant-concentration) or Neumann (no-flux) boundary conditions in a custom planar configuration using programmable illumination for the perturbations. The differences between the observed network dynamics for each boundary condition are described. Using light, we demonstrate the ability to control the initial conditions of the network and to cause individual oscillators within the network to undergo sustained period elongation or a one-time phase delay. PMID:26117136

  16. Effects of perturbations to balance on neuromechanics of fast changes in direction during locomotion.

    Directory of Open Access Journals (Sweden)

    Anderson Souza Oliveira

    Full Text Available This study investigated whether the modular control of changes in direction while running is influenced by perturbations to balance. Twenty-two healthy men performed 90° side-step unperturbed cutting manoeuvres while running (UPT as well as manoeuvres perturbed at initial contact (PTB, 10 cm translation of a moveable force platform. Surface EMG activity from 16 muscles of the supporting limb and trunk, kinematics, and ground reaction forces were recorded. Motor modules composed by muscle weightings and their respective activation signals were extracted from the EMG signals by non-negative matrix factorization. Knee joint moments, co-contraction ratios and co-contraction indexes (hamstrings/quadriceps and motor modules were compared between UPT and PTB. Five motor modules were enough to reconstruct UPT and PTB EMG activity (variance accounted for UPT  = 92 ± 5%, PTB = 90 ± 6%. Moreover, higher similarities between muscle weightings from UPT and PTB (similarity = 0.83 ± 0.08 were observed in comparison to the similarities between the activation signals that drive the temporal properties of the motor modules (similarity = 0.71 ± 0.18. In addition, the reconstruction of PTB EMG from fixed muscle weightings from UPT resulted in higher reconstruction quality (82 ± 6% when compared to reconstruction of PTB EMG from fixed activation signals from UPT (59 ± 11%. Perturbations at initial contact reduced knee abduction moments (7%, as well as co-contraction ratio (11% and co-contraction index (12% shortly after the perturbation onset. These changes in co-contraction ratio and co-contraction index were caused by a reduced activation of hamstrings that was also verified in the activation signals of the specific motor module related to initial contact. Our results suggested that perturbations to balance influence modular control of cutting manoeuvres, especially the temporal properties of muscle recruitment, due to altered afferent

  17. Direct seeding woody species for restoration of bottomlands

    Science.gov (United States)

    Twedt, D.J.; Connor, Kristina F

    2006-01-01

    I direct seeded (broadcast) seeds of 39 species of trees and shrubs using an ATV-mounted rotary spreader to initiate restoration of bottomland forest on retired agricultural sites. Four sites were planted during February, 2000, and 13 additional sites were planted during April and May, 2001. After two growing seasons, stem density of direct-seeded species varied greatly among study plots (range = 0 to 888 stems/ha) but averaged only 110 stems/ha. I recommend that future efforts at direct seeding focus on seven shrub species (Amorpha fruticosa L., Cephalanthus occidentalis L., Cornus spp., Crataegus spp., Ilex decidua Walt., Morus rubra L., and Prunus spp.) and seven tree species (Celtis laevigata Willd., Diospyros virginiana L., Fraxinus spp., Gleditsia triacanthos L., Robinia pseudoacacia L., Taxodium distichum (L.) Rich, and Ulmus spp.) that successfully established in these trials.

  18. Osmopriming on Sesbania virgata (CAV. PERS (Fabaceae seeds

    Directory of Open Access Journals (Sweden)

    Tathiana Elisa Masetto

    2013-12-01

    Full Text Available This study evaluated the effect of the osmopriming on germination and vigour of Sesbania virgata seeds. Seeds were chemically scarified in concentrated sulphuric acid for 40 minutes and put to germinate either directly or after being submitted to osmopriming, drying and accelerated aging. Osmopriming was carried out with polyethylene glycol solutions (PEG 8000 at the following osmotic potentials-0.2; -0.4; -0.6 and -0.8 MPa for 12, 24 and 48 hours. After osmopriming, seeds were dried in silica gel until the initial moisture content was reached, and then submitted to the accelerated aging (48 h/100% RH. The effects of osmopriming and accelerated aging were evaluated through germination test, first counting germination and germination speed index. The osmopriming, followed or not by accelerated aging, positively influenced germination and vigour of Sesbania virgata seeds.

  19. Evaluation of Dacryodes edulis (native pear) seed biomass for Pb (II ...

    African Journals Online (AJOL)

    Dacryodes edulis (Native pear) seed is herein evaluated as a promising biomass for Pb(II) removal from aqueous solution. The Pb(II) adsorption onto Dacryodes edulis seed biomass was influenced by the solution pH, time, biomass dose and initial adsorbate concentration. The Freundlich model fitted better than the ...

  20. Bad seeds sprout perilous dynamics: stochastic thermostat induced trajectory synchronization in biomolecules

    International Nuclear Information System (INIS)

    Voter, A. F.; Sindhikara, Daniel J.; Kim, Seonah; Roitberg, Adrian E.

    2009-01-01

    Molecular dynamics simulations starting from different initial conditions are commonly used to mimic the behavior of an experimental ensemble. We show in this article that when a Langevin thermostat is used to maintain constant temperature during such simulations, extreme care must be taken when choosing the random number seeds used in order to prevent statistical correlation among the MD trajectories. While recent studies have shown that stochastically thermostatted trajectories evolving within a single potential basin with identical random number seeds tend to synchronize, we show that there is a synchronization effect even for complex, biologically relevant systems. We demonstrate this effect in simulations of Alanine trimer and pentamer and in a simulation of a temperature-jump experiment for peptide folding of a 14-residue peptide. Even in replica-exchange simulations, in which the trajectories are at different temperatures, we find partial synchronization occurring when the same random number seed is employed. We explain this by extending the recent derivation of the synchronization effect for two trajectories in a harmonic well to the case in which the trajectories are at two different temperatures. Our results suggest several ways in which mishandling selection of a pseudo random number generator initial seed can lead to corruption of simulation data. Simulators can fall into this trap in simple situations such as neglecting to specifically indicate different random seeds in either parallel or sequential restart simulations, utilizing a simulation package with a weak pseudorandom number generator, or using an advanced simulation algorithm that hasn't been programmed to distribute initial seeds

  1. Bad Seeds Sprout Perilous Dynamics: Stochastic Thermostat Induced Trajectory Synchronization in Biomolecules.

    Science.gov (United States)

    Sindhikara, Daniel J; Kim, Seonah; Voter, Arthur F; Roitberg, Adrian E

    2009-06-09

    Molecular dynamics simulations starting from different initial conditions are commonly used to mimic the behavior of an experimental ensemble. We show in this article that when a Langevin thermostat is used to maintain constant temperature during such simulations, extreme care must be taken when choosing the random number seeds to prevent statistical correlation among the MD trajectories. While recent studies have shown that stochastically thermostatted trajectories evolving within a single potential basin with identical random number seeds tend to synchronize, we show that there is a synchronization effect even for complex, biologically relevant systems. We demonstrate this effect in simulations of alanine trimer and pentamer and in a simulation of a temperature-jump experiment for peptide folding of a 14-residue peptide. Even in replica-exchange simulations, in which the trajectories are at different temperatures, we find partial synchronization occurring when the same random number seed is employed. We explain this by extending the recent derivation of the synchronization effect for two trajectories in a harmonic well to the case in which the trajectories are at two different temperatures. Our results suggest several ways in which mishandling selection of a pseudorandom number generator initial seed can lead to corruption of simulation data. Simulators can fall into this trap in simple situations such as neglecting to specifically indicate different random seeds in either parallel or sequential restart simulations, utilizing a simulation package with a weak pseudorandom number generator, or using an advanced simulation algorithm that has not been programmed to distribute initial seeds.

  2. Regenerative role of seed banks following an intense soil disturbance

    Science.gov (United States)

    Luzuriaga, Arantzazu L.; Escudero, Adrián; Olano, José Miguel; Loidi, Javier

    2005-02-01

    Our main aim was to determine the contribution of the seed bank to vegetation regeneration following a disturbance consisting in a deep ploughing and a thorough homogenisation of a perennial grassland. In the seed bank prior to disturbance, seed distribution through the vertical soil profile was evaluated to determine the initial seed species structure. Then, several characteristics of the shallow seed bank and the extant vegetation were evaluated prior and following field disturbance: seed species composition and abundance, and species composition of the aboveground vegetation. The contribution of seed rain versus seed bank was evaluated by means of the comparison of the vegetation developed in plots filled with sterilised soil (seed bank removal) and the vegetation developed in non-sterilised plots in the field. The distribution of seeds through the profile indicated a sharp decline in abundance with depth, and it was probably linked to propagule morphology, with small and rounded seeds proner to being buried deeper than larger seeds. In the grassland prior to disturbance, the aboveground vegetation and seed bank species composition showed very low similarity index, most likely because during the 5 years following field abandonment, sheep pressure had caused a faster change in aboveground vegetation species composition than in seed bank species composition. Ploughing and homogenisation of the grassland led to low seed abundance in the shallow soil layer caused by dilution of the seed bank. Regardless of impoverishment in seed abundance and species richness, comparison between sterilised and non-sterilised plots showed that the seed bank acted as an effective source of colonising species and determined the aboveground species composition. To summarise, this study outlines the importance of considering several characteristics of the seed bank, such as species composition and seed abundance, in the understanding of the function of seed bank and dynamics of the

  3. Seed priming and transgenerational drought memory improves tolerance against salt stress in bread wheat.

    Science.gov (United States)

    Tabassum, Tahira; Farooq, Muhammad; Ahmad, Riaz; Zohaib, Ali; Wahid, Abdul

    2017-09-01

    This study was conducted to evaluate the potential of seed priming following terminal drought on tolerance against salt stress in bread wheat. Drought was imposed in field sown wheat at reproductive stage (BBCH growth stage 49) and was maintained till physiological maturity (BBCH growth stage 83). Seeds of bread wheat, collected from crop raised under terminal drought and/or well-watered conditions, were subjected to hydropriming and osmopriming (with 1.5% CaCl 2 ) and were sown in soil-filled pots. After stand establishment, salt stress treatments viz. 10 mM NaCl (control) and 100 mM NaCl were imposed. Seed from terminal drought stressed source had less fat (5%), and more fibers (11%), proteins (22%) and total soluble phenolics (514%) than well-watered seed source. Salt stress reduced the plant growth, perturbed water relations and decreased yield. However, an increase in osmolytes accumulation (4-18%), malondialdehyde (MDA) (27-35%) and tissue Na + contents (149-332%) was observed under salt stress. The seeds collected from drought stressed crop had better tolerance against salt stress as indicated by better yield (28%), improved water relations (3-18%), osmolytes accumulation (21-33%), and less MDA (8%) and Na contents (35%) than progeny of well-watered crop. Seed priming, osmopriming in particular, further improved the tolerance against salt stress through improvement in leaf area, water relations, leaf proline, glycine betaine and grain yield while lowering MDA and Na + contents. In conclusion, changed seed composition during terminal drought and seed priming improved the salt tolerance in wheat by modulating the water relations, osmolytes accumulation and lipid peroxidation. Copyright © 2017 Elsevier Masson SAS. All rights reserved.

  4. Non-Perturbative Asymptotic Improvement of Perturbation Theory and Mellin-Barnes Representation

    Directory of Open Access Journals (Sweden)

    Samuel Friot

    2010-10-01

    Full Text Available Using a method mixing Mellin-Barnes representation and Borel resummation we show how to obtain hyperasymptotic expansions from the (divergent formal power series which follow from the perturbative evaluation of arbitrary ''N-point'' functions for the simple case of zero-dimensional φ4 field theory. This hyperasymptotic improvement appears from an iterative procedure, based on inverse factorial expansions, and gives birth to interwoven non-perturbative partial sums whose coefficients are related to the perturbative ones by an interesting resurgence phenomenon. It is a non-perturbative improvement in the sense that, for some optimal truncations of the partial sums, the remainder at a given hyperasymptotic level is exponentially suppressed compared to the remainder at the preceding hyperasymptotic level. The Mellin-Barnes representation allows our results to be automatically valid for a wide range of the phase of the complex coupling constant, including Stokes lines. A numerical analysis is performed to emphasize the improved accuracy that this method allows to reach compared to the usual perturbative approach, and the importance of hyperasymptotic optimal truncation schemes.

  5. Fresh and matured lamb meat quality fed with sunflower seeds and vitamin E

    OpenAIRE

    Sales,Ronaldo Oliveira; Silva Sobrinho,Américo Garcia da; Zeola,Nivea Maria Brancacci Lopes; Lima,Natália Ludmila Lins; Manzi,Gabriela Milani; Almeida,Fabiana Alves de; Endo,Viviane

    2013-01-01

    The objective of the study is to evaluate meat quality from Ile de France lamb fed diets supplemented with sunflower seeds and vitamin E. Thirty-two lamb weighing initially 15kg were housed in individual stalls and slaughtered when body weight reached 32kg. The treatments consisted of four experimental diets: D1) sugarcane + concentrate without sunflower seeds; D2) sugarcane + concentrate with sunflower seeds; D3) sugarcane + concentrate without sunflower seeds plus 1000mg vitamin E kg-1 diet...

  6. Activation of Arabidopsis seed hair development by cotton fiber-related genes.

    Directory of Open Access Journals (Sweden)

    Xueying Guan

    Full Text Available Each cotton fiber is a single-celled seed trichome or hair, and over 20,000 fibers may develop semi-synchronously on each seed. The molecular basis for seed hair development is unknown but is likely to share many similarities with leaf trichome development in Arabidopsis. Leaf trichome initiation in Arabidopsis thaliana is activated by GLABROUS1 (GL1 that is negatively regulated by TRIPTYCHON (TRY. Using laser capture microdissection and microarray analysis, we found that many putative MYB transcription factor and structural protein genes were differentially expressed in fiber and non-fiber tissues. Gossypium hirsutum MYB2 (GhMYB2, a putative GL1 homolog, and its downstream gene, GhRDL1, were highly expressed during fiber cell initiation. GhRDL1, a fiber-related gene with unknown function, was predominately localized around cell walls in stems, sepals, seed coats, and pollen grains. GFP:GhRDL1 and GhMYB2:YFP were co-localized in the nuclei of ectopic trichomes in siliques. Overexpressing GhRDL1 or GhMYB2 in A. thaliana Columbia-0 (Col-0 activated fiber-like hair production in 4-6% of seeds and had on obvious effects on trichome development in leaves or siliques. Co-overexpressing GhRDL1 and GhMYB2 in A. thaliana Col-0 plants increased hair formation in ∼8% of seeds. Overexpressing both GhRDL1 and GhMYB2 in A. thaliana Col-0 try mutant plants produced seed hair in ∼10% of seeds as well as dense trichomes inside and outside siliques, suggesting synergistic effects of GhRDL1 and GhMYB2 with try on development of trichomes inside and outside of siliques and seed hair in A. thaliana. These data suggest that a different combination of factors is required for the full development of trichomes (hairs in leaves, siliques, and seeds. A. thaliana can be developed as a model a system for discovering additional genes that control seed hair development in general and cotton fiber in particular.

  7. Characterization biometric and morphophysiological of Peach rootstock seeds using images of their seedling vigor.

    Science.gov (United States)

    Souza, Aline Das Graças; Smiderle, Oscar Jose; Bianchi, Valmor Joao

    2018-04-26

    This study aimed to evaluate the efficiency of using the computerized imaging seed analysis system (SAS) in the biometric and morphophysiological characterization of seeds and the initial growth of seedlings from peach rootstocks. The experimental design was completely randomized with five replicates of 20 seeds. The variables analyzed were degree of seed humidity, length and width of seeds measured by SAS technology and manual measurements, mean germination time, germination percentage, radicle length and width, taproot length, length of the aerial part and taproot/aerial part ratio. The highest seed length, germination percentage (100%) and lower germination time (11.3), were obtained with the cv. Capdeboscq while, 'Tsukuba 1', 2' and 3' had intermediate seedlings length, varying from 1.55 to 1.65 cm with mean germination times between 14.5 and 18.0 days and average germination percentage of 96%. The computerized analysis of images is fast and efficient for biometric evaluations such as seed width and length, as well as initial growth of peach tree seedlings. The cvs Capdeboscq, Flordaguard and Tsukuba 2 presented greater radicle width, length and a mean taproot/aerial part ratio equal to 2, as well as higher number of adventitious roots, which indicated a strong positive correlation between radicle length, taproot length and initial seedling growth. The continuity of the research will certainly allow the development of reliable procedures for other species, besides allowing the identification of wider alternatives for the use of this system for the expansion of knowledge in the areas of physiology and evaluation of the physiological potential of seeds. Copyright© Bentham Science Publishers; For any queries, please email at epub@benthamscience.org.

  8. Optimal perturbations for nonlinear systems using graph-based optimal transport

    Science.gov (United States)

    Grover, Piyush; Elamvazhuthi, Karthik

    2018-06-01

    We formulate and solve a class of finite-time transport and mixing problems in the set-oriented framework. The aim is to obtain optimal discrete-time perturbations in nonlinear dynamical systems to transport a specified initial measure on the phase space to a final measure in finite time. The measure is propagated under system dynamics in between the perturbations via the associated transfer operator. Each perturbation is described by a deterministic map in the measure space that implements a version of Monge-Kantorovich optimal transport with quadratic cost. Hence, the optimal solution minimizes a sum of quadratic costs on phase space transport due to the perturbations applied at specified times. The action of the transport map is approximated by a continuous pseudo-time flow on a graph, resulting in a tractable convex optimization problem. This problem is solved via state-of-the-art solvers to global optimality. We apply this algorithm to a problem of transport between measures supported on two disjoint almost-invariant sets in a chaotic fluid system, and to a finite-time optimal mixing problem by choosing the final measure to be uniform. In both cases, the optimal perturbations are found to exploit the phase space structures, such as lobe dynamics, leading to efficient global transport. As the time-horizon of the problem is increased, the optimal perturbations become increasingly localized. Hence, by combining the transfer operator approach with ideas from the theory of optimal mass transportation, we obtain a discrete-time graph-based algorithm for optimal transport and mixing in nonlinear systems.

  9. Effective seeding strategy in evolutionary prisoner's dilemma games on online social networks

    Science.gov (United States)

    Xu, Bo; Shi, Huibin; Wang, Jianwei; Huang, Yun

    2015-04-01

    This paper explores effective seeding strategies in prisoner's dilemma game (PDG) on online social networks, i.e. the optimal strategy to obtain global cooperation with minimum cost. Three distinct seeding strategies are compared by performing computer simulations on real online social network datasets. Our finding suggests that degree centrality seeding outperforms other strategies regardless of the initial payoff setting or network size. Celebrities of online social networks play key roles in preserving cooperation.

  10. Thermal Changes of Maize Seed by Laser Irradiation

    Science.gov (United States)

    Hernandez-Aguilar, C.; Dominguez-Pacheco, A.; Cruz-Orea, A.

    2015-09-01

    In this research, the thermal evolution in maize seeds ( Zea mays L.) was studied when low-intensity laser irradiation was applied during 60 s. The seeds were irradiated in three different conditions: suspended in air, placed on an aluminum surface, and finally placed on a cardboard; the evolution of the seed temperature was measured by an infrared camera. Photoacoustic spectroscopy and the Rosencwaig and Gersho model were used to determine the optical absorption coefficient (β ) of the seeds. The results indicate that using 650 nm laser light and 27.4 mW, it is possible to produce temperature changes (up to 9.06°C after 1 min) on the seeds. Comparing the mean temperature of the seeds, during and after the incidence of light from a laser, it was found that there were statistically significant differences (P≤ 0.05) from time t1 to time t_{16} (t1 to t_{16}) and t3 to t_{16}, for the laser turned on and off, respectively. The seed condition that had the highest temperature variation, relative to the initial temperature (during the irradiation laser exposure), involved the seeds suspended in air. With regard to the stage of decay of the temperature, it was found that the seed condition that decays more slowly was the seed placed on the cardboard. It was also found that black-dyed maize seeds are optically opaque in the 300 nm to 700 nm range Also, the thermal diffusion length is smaller than the optical penetration length. In the present investigation, it was shown that there is a thermal component associated with the mechanisms of laser biostimulation, which is also a function of the container materials of the seed. In this way, the effects of laser treatment on maize seeds involve at least a temperature effect. It is important to know the temperature changes in the seeds that have been irradiated with a laser beam since they could have substantial practical and theoretical importance.

  11. Suppression of Runaway Electrons by Resonant Magnetic Perturbations in TEXTOR Disruptions

    International Nuclear Information System (INIS)

    Lehnen, M.; Bozhenkov, S. A.; Abdullaev, S. S.; TEXTOR Team,; Jakubowski, M. W.

    2008-01-01

    The generation of runaway electrons in the international fusion experiment ITER disruptions can lead to severe damage at plasma facing components. Massive gas injection might inhibit the generation process, but the amount of gas needed can affect, e.g., vacuum systems. Alternatively, magnetic perturbations can suppress runaway generation by increasing the loss rate. In TEXTOR disruptions runaway losses were enhanced by the application of resonant magnetic perturbations with toroidal mode number n=1 and n=2. The disruptions are initiated by fast injection of about 3x10 21 argon atoms, which leads to a reliable generation of runaway electrons. At sufficiently high perturbation levels a reduction of the runaway current, a shortening of the current plateau, and the suppression of high energetic runaways are observed. These findings indicate the suppression of the runaway avalanche during disruptions

  12. Control, pressure perturbations, displacements, and disruptions in highly elongated tokamak plasmas

    International Nuclear Information System (INIS)

    Marcus, F.B.; Hofmann, F.; Tonetti, G.; Jardin, S.C.; Noll, P.

    1989-06-01

    The control and evolution of highly elongated tokamak plasmas with large growth rates are simulated with the axisymmetric, resistive MHD code TSC in the geometry of the TCV tokamak. Pressure perturbations such as sawteeth and externally programmed displacements create initial velocity perturbations which may be stabilized by low power, rapid response coils inside the passively stabilizing vacuum vessel, together with slower shaping coils outside the vessel. Vertical disruption induced voltages and forces on the rapid coils and vessel are investigated, and a model is proposed for an additional vertical force due to poloidal currents. (author) 6 figs., 1 tab., 26 refs

  13. Perennial soybean seeds coated with high doses of boron and zinc ...

    African Journals Online (AJOL)

    The objective of this work was to study combinations of high doses of boron (B) and zinc (Zn) in the recoating of perennial soybean seeds, in order to provide these nutrients to the future plants. The physical, physiological and nutritional characteristics of the coated seeds and initial development of plants in a greenhouse ...

  14. Does the informal seed system threaten cowpea seed health?

    NARCIS (Netherlands)

    Biemond, P.C.; Oguntade, O.; Lava Kumar, P.; Stomph, T.J.; Termorshuizen, A.J.; Struik, P.C.

    2013-01-01

    Most smallholder farmers in developing countries depend on an informal Seed System (SS) for their seed. The informal SS is often criticized because farmer-produced seed samples are not tested for seed health, thus accepting the risk of planting infected seeds. Here we aimed at assessing the quality

  15. A nonlinear inversion for the velocity background and perturbation models

    KAUST Repository

    Wu, Zedong

    2015-08-19

    Reflected waveform inversion (RWI) provides a method to reduce the nonlinearity of the standard full waveform inversion (FWI) by inverting for the single scattered wavefield obtained using an image. However, current RWI methods usually neglect diving waves, which is an important source of information for extracting the long wavelength components of the velocity model. Thus, we propose a new optimization problem through breaking the velocity model into the background and the perturbation in the wave equation directly. In this case, the perturbed model is no longer the single scattering model, but includes all scattering. We optimize both components simultaneously, and thus, the objective function is nonlinear with respect to both the background and perturbation. The new introduced w can absorb the non-smooth update of background naturally. Application to the Marmousi model with frequencies that start at 5 Hz shows that this method can converge to the accurate velocity starting from a linearly increasing initial velocity. Application to the SEG2014 demonstrates the versatility of the approach.

  16. Stationary axially symmetric perturbations of a rotating black hole. [Space-time perturbation, Newman-Penrose formalism

    Energy Technology Data Exchange (ETDEWEB)

    Demianski, M [California Inst. of Tech., Pasadena (USA)

    1976-07-01

    A stationary axially symmetric perturbation of a rotating black hole due to a distribution of test matter is investigated. The Newman-Penrose spin coefficient formalism is used to derive a general set of equations describing the perturbed space-time. In a linear approximation it is shown that the mass and angular momentum of a rotating black hole is not affected by the perturbation. The metric perturbations near the horizon are given. It is concluded that given a perturbing test fluid distribution, one can always find a corresponding metric perturbation such that the mass and angular momentum of the black hole are not changed. It was also noticed that when a tends to M, those perturbed spin coefficients and components of the Weyl tensor which determine the intrinsic properties of the incoming null cone near the horizon grow indefinitely.

  17. Low gamma radiation dose effect on germination and initial growing of black beans (Phaseolus vulgaris L.) seeds

    International Nuclear Information System (INIS)

    Jesus, Edgar F.O. de; Silva, Anderson de O. Melo; Marsico, Eliane T.

    2005-01-01

    In this work we analyze the effect of low gamma irradiation doses and low concentrations of sodium alginate on the germination and growing of black beans seeds. The seeds were obtained from an organic farmer at Nova Friburgo, Rio de Janeiro State. The seeds were submitted to radiation doses between 0 and 150 Gy with a Cobalt 60 source in a Gammacell Excel 220 Nordion Irradiator with a dose rate of 70 Gy/min. After germination the seeds were left to grow three weeks on a hydroponics system. The system used was the water culture with nutritive solution that was supplemented with the nutritional needs for plant grows. We also tested the influence of the sodium alginate on the plant grows. A 4% solution of sodium alginate in distilled water was irradiated with 120 kGy gamma ray dose. Concentrations of sodium alginate irradiated and non-irradiated varying from 50 to 500 μg/g were used in the hydroponics' solution. After three weeks the mass and the height of the plant were measured. Statistic analyses of he result with the SAS program show that there was no significant difference between the height and mass of seeds submitted different doses, but irradiated solution of sodium alginate with concentration of 400 and 500 μg/g present a significant difference on plant grow. (author)

  18. NEXCADE: perturbation analysis for complex networks.

    Directory of Open Access Journals (Sweden)

    Gitanjali Yadav

    Full Text Available Recent advances in network theory have led to considerable progress in our understanding of complex real world systems and their behavior in response to external threats or fluctuations. Much of this research has been invigorated by demonstration of the 'robust, yet fragile' nature of cellular and large-scale systems transcending biology, sociology, and ecology, through application of the network theory to diverse interactions observed in nature such as plant-pollinator, seed-dispersal agent and host-parasite relationships. In this work, we report the development of NEXCADE, an automated and interactive program for inducing disturbances into complex systems defined by networks, focusing on the changes in global network topology and connectivity as a function of the perturbation. NEXCADE uses a graph theoretical approach to simulate perturbations in a user-defined manner, singly, in clusters, or sequentially. To demonstrate the promise it holds for broader adoption by the research community, we provide pre-simulated examples from diverse real-world networks including eukaryotic protein-protein interaction networks, fungal biochemical networks, a variety of ecological food webs in nature as well as social networks. NEXCADE not only enables network visualization at every step of the targeted attacks, but also allows risk assessment, i.e. identification of nodes critical for the robustness of the system of interest, in order to devise and implement context-based strategies for restructuring a network, or to achieve resilience against link or node failures. Source code and license for the software, designed to work on a Linux-based operating system (OS can be downloaded at http://www.nipgr.res.in/nexcade_download.html. In addition, we have developed NEXCADE as an OS-independent online web server freely available to the scientific community without any login requirement at http://www.nipgr.res.in/nexcade.html.

  19. Cosmological perturbations in transient phantom inflation scenarios

    Energy Technology Data Exchange (ETDEWEB)

    Richarte, Martin G. [Universidade Federal do Parana, Departamento de Fisica, Caixa Postal 19044, Curitiba (Brazil); Universidad de Buenos Aires, Ciudad Universitaria 1428, Departamento de Fisica, Facultad de Ciencias Exactas y Naturales, Buenos Aires (Argentina); Kremer, Gilberto M. [Universidade Federal do Parana, Departamento de Fisica, Caixa Postal 19044, Curitiba (Brazil)

    2017-01-15

    We present a model of inflation where the inflaton is accommodated as a phantom field which exhibits an initial transient pole behavior and then decays into a quintessence field which is responsible for a radiation era. We must stress that the present unified model only deals with a single field and that the transition between the two eras is achieved in a smooth way, so the model does not suffer from the eternal inflation issue. We explore the conditions for the crossing of the phantom divide line within the inflationary era along with the structural stability of several critical points. We study the behavior of the phantom field within the slow-climb approximation along with the necessary conditions to have sufficient inflation. We also examine the model at the level of classical perturbations within the Newtonian gauge and determine the behavior of the gravitational potential, contrast density and perturbed field near the inflation stage and the subsequent radiation era. (orig.)

  20. Precipitation formation from orographic cloud seeding.

    Science.gov (United States)

    French, Jeffrey R; Friedrich, Katja; Tessendorf, Sarah A; Rauber, Robert M; Geerts, Bart; Rasmussen, Roy M; Xue, Lulin; Kunkel, Melvin L; Blestrud, Derek R

    2018-02-06

    Throughout the western United States and other semiarid mountainous regions across the globe, water supplies are fed primarily through the melting of snowpack. Growing populations place higher demands on water, while warmer winters and earlier springs reduce its supply. Water managers are tantalized by the prospect of cloud seeding as a way to increase winter snowfall, thereby shifting the balance between water supply and demand. Little direct scientific evidence exists that confirms even the basic physical hypothesis upon which cloud seeding relies. The intent of glaciogenic seeding of orographic clouds is to introduce aerosol into a cloud to alter the natural development of cloud particles and enhance wintertime precipitation in a targeted region. The hypothesized chain of events begins with the introduction of silver iodide aerosol into cloud regions containing supercooled liquid water, leading to the nucleation of ice crystals, followed by ice particle growth to sizes sufficiently large such that snow falls to the ground. Despite numerous experiments spanning several decades, no direct observations of this process exist. Here, measurements from radars and aircraft-mounted cloud physics probes are presented that together show the initiation, growth, and fallout to the mountain surface of ice crystals resulting from glaciogenic seeding. These data, by themselves, do not address the question of cloud seeding efficacy, but rather form a critical set of observations necessary for such investigations. These observations are unambiguous and provide details of the physical chain of events following the introduction of glaciogenic cloud seeding aerosol into supercooled liquid orographic clouds.

  1. Stevia rebaudiana (Bert Bertoni: influence of osmotic stress and seed priming on seed germination under laboratory conditions

    Directory of Open Access Journals (Sweden)

    Keila Regina Hossa

    2017-05-01

    Full Text Available The foremost factor necessary for plant growers cultivating large acreages of Stevia rebaudiana (Bert Bertoni is the production of qualitative bedding plants. The objective of this study was to evaluate the influence of osmotic-priming on the uniformity of seed germination. First, we evaluated the percentage of normal seedlings from two seed samples harvested in 2011 and 2012. The seeds harvested in 2012 produced 71.4% normal seedlings and thus they were used in the next experiments. The seeds were subjected to osmotic stress using five concentrations of polyethylene glycol (PEG-6000 at -0.2, -0.4, -0.6, -0.8, and -1.0 MPa in contrast with distilled water. Based on these first results, only -0.8 and -1.0 MPa were evaluated in the third experiment. The seeds were immersed in both concentrations of polyethylene glycol (PEG-6000 for imbibing at 20ºC for four, five, six, and seven days. Thereafter, we evaluated the time to the first normal seedling (Ti, time to the last normal seedling (Tf, percentage normal seedlings at the initial time (Pi and percentage of normal seedlings at the end of every treatment (Pf. Osmotic priming increased the percentage of normal seedlings of the Stevia rebaudiana and reduced the time to the first and last germination events.

  2. Comparing the effects of mechanical perturbation training with a compliant surface and manual perturbation training on joints kinematics after ACL-rupture.

    Science.gov (United States)

    Nawasreh, Zakariya; Failla, Mathew; Marmon, Adam; Logerstedt, David; Snyder-Mackler, Lynn

    2018-05-23

    Performing physical activities on a compliant surface alters joint kinematics and increases joints stiffness. However, the effect of compliant surface on joint kinematics after ACL-rupture is yet unknown. To compare the effects of mechanical perturbation training with a compliant surface to manual perturbation training on joint kinematics after ACL-rupture. Sixteen level I/II athletes with ACL-rupture participated in this preliminary study. Eight patients received mechanical perturbation with compliant surface (Mechanical) and 8 patients received manual perturbation training (Manual). Patients completed standard gait analysis before (Pre) and after (Post) training. Significant group-by-time interactions were found for knee flexion angle at initial contact (IC) and peak knee flexion (PKF) (pMechanical:27.68+4.08°, p = 0.011), hip rotation angle at PKE (Manual:-3.40+4.78°, Mechanical:5.43+4.78°, p Mechanical:0.55+2.23°, p = 0.039). Main effects of time were found for hip adduction angle at PKE (Pre:6.98+4.48°, Post:8.41+4.91°, p = 0.04), knee adduction angle at IC (Pre:-2.90+3.50°, Post:-0.62+2.58°, p = 0.03), ankle adduction angle at IC (Pre:2.16+3.54, Post:3.8+3.68, p = 0.008), and ankle flexion angle at PKF (Pre:-4.55+2.77°, Post:-2.39+3.48°, p = 0.01). Training on a compliant surface induces different effects on joint kinematics compared to manual perturbation training after ACL-rupture. Manual perturbation improved hip alignment and increased knee flexion angles, while mechanical training decreased knee flexion angles throughout the stance phase. Administering training on a compliant surface after ACL-rupture may help improving dynamic knee stability, however, long-term effects on knee health needs to be determined. Copyright © 2018 Elsevier B.V. All rights reserved.

  3. On the relative contributions of wind vs. animals to seed dispersal of four Sierra Nevada pines.

    Science.gov (United States)

    Vander Wall, Stephen B

    2008-07-01

    Selective pressures that influence the form of seed dispersal syndromes are poorly understood. Morphology of plant propagules is often used to infer the means of dispersal, but morphology can be misleading. Several species of pines, for example, have winged seeds adapted for wind dispersal but owe much of their establishment to scatter-hoarding animals. Here the relative importance of wind vs. animal dispersal is assessed for four species of pines of the eastern Sierra Nevada that have winged seeds but differed in seed size: lodgepole pine (Pinus contorta murrayana, 8 mg); ponderosa pine (Pinus ponderosa ponderosa, 56 mg); Jeffrey pine (Pinus jeffreyi, 160 mg); and sugar pine (Pinus lambertiana, 231 mg). Pre-dispersal seed mortality eliminated much of the ponderosa pine seed crop (66%), but had much less effect on Jeffrey pine (32% of seeds destroyed), lodgepole pine (29%), and sugar pine (7%). When cones opened most filled seeds were dispersed by wind. Animals removed > 99% of wind-dispersed Jeffrey and sugar pine seeds from the ground within 60 days, but animals gathered only 93% of lodgepole pine seeds and 38% of ponderosa pine seeds during the same period. Animals gathered and scatter hoarded radioactively labeled ponderosa, Jeffrey, and sugar pine seeds, making a total of 2103 caches over three years of study. Only three lodgepole pine caches were found. Caches typically contained 1-4 seeds buried 5-20 mm deep, depths suitable for seedling emergence. Although Jeffrey and sugar pine seeds are initially wind dispersed, nearly all seedlings arise from animal caches. Lodgepole pine is almost exclusively wind dispersed, with animals acting as seed predators. Animals treated ponderosa pine in an intermediate fashion. Two-phased dispersal of large, winged pine seeds appears adaptive; initial wind dispersal helps to minimize pre-dispersal seed mortality whereas scatter hoarding by animals places seeds in sites with a higher probability of seedling establishment.

  4. Germination and development of pecan cultivar seedlings by seed stratification

    Directory of Open Access Journals (Sweden)

    Igor Poletto

    2015-12-01

    Full Text Available Abstract: The objective of this work was to evaluate the effect of seed stratification on germination rate, germination speed, and initial development of seedlings of six pecan (Carya illinoinensis cultivars under subtropical climatic conditions in southern Brazil. For stratification, the seeds were placed in boxes with moist sand, in a cold chamber at 4°C, for 90 days. In the fourteenth week after sowing, the emergence speed index, total emergence, plant height, stem diameter, and number of leaves were evaluated. Seed stratification significantly improves the germination potential and morphological traits of the evaluated cultivars.

  5. Transcendental smallness in singularly perturbed equations of volterra type

    International Nuclear Information System (INIS)

    Bijura, Angelina M.

    2003-11-01

    The application of different limit processes to a physical problem is an important tool in layer type techniques. Hence the study of initial layer correction functions is of central importance for understanding layer-type problems. It is shown that for singularly perturbed problems of Volterra type, the concept of transcendental smallness is an asymptotic one. Transcendentally small terms may be numerically important. (author)

  6. Kinetics of solute leachate from imbibing Caesalpinia echinata Lam. (Brazilwood seeds

    Directory of Open Access Journals (Sweden)

    Nestor Martini Neto

    2014-02-01

    Full Text Available The electrical conductivity of leachates from imbibing seeds has been used as a vigor test for several species. The adaptation of this methodology to different species requires knowledge on the leaching kinetics of electrolytes. For Brazilwood seeds, the classic method was not satisfactory and rapid tests are essential because they have low storage capacity at room temperature. Leaching kinetics during seed imbibition is a function of physiological quality, presence or absence of seed coat, imbibing temperature and the initial moisture content of seed. In this study, the electrolyte leaching rate of six different categories of seeds, from two regions, was evaluated in seeds with and without seed coat and incubated with different moisture contents and at different temperatures. The results showed that the electrolyte leaching rate in Brazilwood seeds is independent of the physiological quality, the presence or absence of seed coat and imbibition temperature, but these factors changed the total amount of electrolytes leached. The leaching rate increased in the first few minutes of imbibition, suggesting that the adjustment of the methodology must consider the reduction in imbibition time, reduction in temperature, use of a controlled and slower pre-imbibition, and replacement of the imbibition solution after the first few minutes.

  7. [Study on seed quality test and quality standard of Pesudostellaria heterophylla].

    Science.gov (United States)

    Xiao, Cheng-Hong; Zhou, Tao; Jiang, Wei-Ke; Chen, Min; Xiong, Hou-Xi; Liao, Ming-Wu

    2014-08-01

    Referring to the rules for agricultural seed testing (GB /T 3543-1995) issued by China, the test of sampling, seed purity, weight per 1 000 seeds, seed moisture, seed viability and germination rate had been studied for screening seed quality test methods of Pesudostellaria heterophylla. The seed quality from different collection areas was measured. The results showed that at least 6.5 g seeds should be sampled and passed through 10-mesh sieve for purity analysis. The weight of 1 000 seeds was determined by using the 500-seed method. The phenotypic observation and size measurement were used for authenticity testing. The seed moisture was determined under the higher temperature (130 ± 2) degrees C for 5 hours. The seeds were dipped into 0.2% TTC sustaining 1 hour at 40 degrees C, then the viability could be determined. The break dormancy seeds were cultured on sand at 10 degrees C. K cluster analysis was applied for the data analysis, the seed quality from different collection areas grading of P. Heterophylla was described as three grades. The seed quality of each grade should reach following requirements: for first grade seeds, germination rate ≥ 86%, 1 000-grain weight ≥ 2.59 g, purity ≥ 87%, moisture ≤ 13.1%; for second grade seeds, germination rate ≥ 70%, 1 000-grain weight ≥ 2.40 g, purity ≥ 77%, moisture ≤ 14.3%; for third grade seeds, germination rate ≥ 41%, 1 000-grain weight ≥ 2.29 g, purity ≥ 76%, moisture ≤ 15.8%. The seed testing methods for quality items of P. heterophylla had been initially established, as well as the primary P. heterophylla seed quality classification standard.

  8. Perturbative and constructive renormalization

    International Nuclear Information System (INIS)

    Veiga, P.A. Faria da

    2000-01-01

    These notes are a survey of the material treated in a series of lectures delivered at the X Summer School Jorge Andre Swieca. They are concerned with renormalization in Quantum Field Theories. At the level of perturbation series, we review classical results as Feynman graphs, ultraviolet and infrared divergences of Feynman integrals. Weinberg's theorem and Hepp's theorem, the renormalization group and the Callan-Symanzik equation, the large order behavior and the divergence of most perturbation series. Out of the perturbative regime, as an example of a constructive method, we review Borel summability and point out how it is possible to circumvent the perturbation diseases. These lectures are a preparation for the joint course given by professor V. Rivasseau at the same school, where more sophisticated non-perturbative analytical methods based on rigorous renormalization group techniques are presented, aiming at furthering our understanding about the subject and bringing field theoretical models to a satisfactory mathematical level. (author)

  9. Accommodation of the spinal cat to a tripping perturbation

    Directory of Open Access Journals (Sweden)

    Hui eZhong

    2012-05-01

    Full Text Available Adult cats with a complete spinal cord transection at T12-T13 can relearn over a period of days-to-weeks how to generate full weight-bearing stepping on a treadmill or standing ability if trained specifically for that task. In the present study, we assessed short-term (msec-min adaptations by repetitively imposing a mechanical perturbation on the hindlimb of chronic spinal cats by placing a rod in the path of the leg during the swing phase to trigger a tripping response. The kinematics and EMG were recorded during control (10 steps, trip (1 to 60 steps with various patterns and then release (without any tripping stimulus, 10 to 20 steps sequences. Our data show that the activation patterns and kinematics of the hindlimb in the step cycle immediately following the initial trip (mechanosensory stimulation of the dorsal surface of the paw was modified in a way that increased the probability of avoiding the obstacle in the subsequent step. This indicates that the spinal sensorimotor circuitry reprogrammed the trajectory of the swing following a perturbation prior to the initiation of the swing phase of the subsequent step, in effect attempting to avoid the re-occurrence of the perturbation. The average height of the release steps was elevated compared to control regardless of the pattern and the length of the trip sequences. In addition, the average impact force on the tripping rod tended to be lower with repeated exposure to the tripping stimulus. EMG recordings suggest that the semitendinosus, a primary knee flexor, was a major contributor to the adaptive tripping response. These results demonstrate that the lumbosacral locomotor circuitry can modulate the activation patterns of the hindlimb motor pools within the time frame of single step in a manner that tends to minimize repeated perturbations. Furthermore, these adaptations remained evident for a number of steps after removal of the mechanosensory stimulation.

  10. The importance of seed mass for early regeneration in tropical forest: a review

    NARCIS (Netherlands)

    Rose, S.A.; Poorter, L.

    2003-01-01

    Seed mass is an important component of the shade tolerance of rain forest tree species. Using a metaanalysis this article evaluates till what extent seed mass affects the survival, initial size, and growth of seedlings in light environments that are typical of forest gaps and understory

  11. Effect of Foley catheters on seed positions and urethral dose in 125I and 103Pd prostate implants

    International Nuclear Information System (INIS)

    Brezovich, Ivan A.; Pareek, Prem N.; Duan, Jun; Fiveash, John

    2001-01-01

    Purpose: To estimate the perturbation of seed position and urethral dose, subsequent to withdrawal of urethral catheters. Methods and Materials: A mathematical model based on the volume incompressibility of tissues was used to compute seed positions and doses following removal of the Foley. The model assumed that the central axis of the urethra remains stationary, and that prostate tissue and seeds move radially toward the center of the urethra to fill the void left by the catheter. Seed motion has also been measured using transrectal ultrasound. Results: Based on the computations, seeds located originally close to the urethra travel relatively large distances toward the urethra upon Foley removal, whereas seeds located further away move substantially less. This seed motion leads to higher urethral doses than shown in a standard treatment plan. Dose enhancements increase with catheter size, decrease with increasing prostate volume, are more pronounced for 103 Pd than for 125 I, and range between 3.5% and 32.4%. Postimplant dosimetry is equally affected if images are taken with urethral catheters in place, showing lower urethral doses than actually delivered. Preliminary ultrasound based measurements of seed motion agree with the theory. Conclusion: During the implantation procedure, 12 fr or smaller urethral catheters are preferable to larger diameter catheters if urine drainage is sufficient. Treatment planners should avoid planning seeds at 5 mm or closer from the urethra. Special caution is indicated in prostates having about 20 cm 3 or smaller volumes, and when 103 Pd is used. Postimplant dosimetry is susceptible to the same errors

  12. Perturbative odderon in the dipole model

    International Nuclear Information System (INIS)

    Kovchegov, Yuri V.; Szymanowski, Lech; Wallon, Samuel

    2004-01-01

    We show that, in the framework of Mueller's dipole model, the perturbative QCD odderon is described by the dipole model equivalent of the BFKL equation with a C-odd initial condition. The eigenfunctions and eigenvalues of the odderon solution are the same as for the dipole BFKL equation and are given by the functions E n,ν and χ(n,ν) correspondingly, where the C-odd initial condition allows only for odd values of n. The leading high-energy odderon intercept is given by α odd -1=((2α s N c )/(π))χ(n=1,ν=0)=0 in agreement with the solution found by Bartels, Lipatov and Vacca. We proceed by writing down an evolution equation for the odderon including the effects of parton saturation. We argue that saturation makes the odderon solution a decreasing function of energy

  13. Talisia esculenta seed quality in function of drying temperatures and times

    Directory of Open Access Journals (Sweden)

    Edson Almeida Cardoso

    2015-02-01

    Full Text Available Talisia esculenta Radlk is a species of the Sapindaceae family native to the Amazon region. Its fruits are principally obtained by collecting in natura; its propagation is by seeds, which are of the recalcitrant type, with low longevity and sensitivity to dehydration. We evaluated the effects of different drying times and temperatures on T. esculenta seeds. The seeds were dried in a forced-air oven at 40, 45, and 50°C for periods of 0, 6, 12, 24, 30, and36 hours, using four replications of 25 seeds each. Tests were conducted to determine seed quality: moisture contents, emergence percentage, first counts, emergence speed index and the length and dry weight of the seedlings. The data was submitted to analysis of variance and polynomial regression, at a 5% level of probability. T. esculenta seeds should be dried at 40 or 45°C for no more than six hours for best initial seedling growth.

  14. Perturbation based Monte Carlo criticality search in density, enrichment and concentration

    International Nuclear Information System (INIS)

    Li, Zeguang; Wang, Kan; Deng, Jingkang

    2015-01-01

    Highlights: • A new perturbation based Monte Carlo criticality search method is proposed. • The method could get accurate results with only one individual criticality run. • The method is used to solve density, enrichment and concentration search problems. • Results show the feasibility and good performances of this method. • The relationship between results’ accuracy and perturbation order is discussed. - Abstract: Criticality search is a very important aspect in reactor physics analysis. Due to the advantages of Monte Carlo method and the development of computer technologies, Monte Carlo criticality search is becoming more and more necessary and feasible. Existing Monte Carlo criticality search methods need large amount of individual criticality runs and may have unstable results because of the uncertainties of criticality results. In this paper, a new perturbation based Monte Carlo criticality search method is proposed and discussed. This method only needs one individual criticality calculation with perturbation tallies to estimate k eff changing function using initial k eff and differential coefficients results, and solves polynomial equations to get the criticality search results. The new perturbation based Monte Carlo criticality search method is implemented in the Monte Carlo code RMC, and criticality search problems in density, enrichment and concentration are taken out. Results show that this method is quite inspiring in accuracy and efficiency, and has advantages compared with other criticality search methods

  15. Understanding Lolium rigidum Seeds: The Key to Managing a Problem Weed?

    Directory of Open Access Journals (Sweden)

    Kathryn J. Steadman

    2012-09-01

    Full Text Available The 40 million hectare southern Australian winter cropping region suffers from widespread infestation by Lolium rigidum (commonly known as annual or rigid ryegrass, a Mediterranean species initially introduced as a pasture plant. Along with its high competitiveness within crops, rapid adaptability and widespread resistance to herbicides, the dormancy of its seeds means that L. rigidum is the primary weed in southern Australian agriculture. With the individuals within a L. rigidum population exhibiting varying levels of seed dormancy, germination can be staggered across the crop-growing season, making complete weed removal virtually impossible, and ensuring that the weed seed bank is constantly replenished. By understanding the processes involved in induction and release of dormancy in L. rigidum seeds, it may be possible to develop strategies to more effectively manage this pest without further stretching herbicide resources. This review examines L. rigidum seed dormancy and germination from a weed-management perspective and explains how the seed bank can be depleted by control strategies encompassing all stages in the lifecycle of a seed, from development to germination.

  16. Quinoa seeds leach phytoecdysteroids and other compounds with anti-diabetic properties

    Science.gov (United States)

    Graf, Brittany L.; Poulev, Alexander; Kuhn, Peter; Grace, Mary H.; Lila, Mary Ann; Raskin, Ilya

    2014-01-01

    Quinoa (Chenopodium quinoa Willd.) contains high levels of biologically active phytoecdysteroids, which have been implicated in plant defense from insects, and have shown a range of beneficial pharmacological effects in mammals. We demonstrated that the most prevalent phytoecdysteroid, 20-hydroxyecdysone (20HE), was secreted (leached) from intact quinoa seeds into water during the initial stages of seed germination. Leaching efficiency was optimized by ethanol concentration (70% ethanol), temperature (80°C), time (4 h), and solvent ratio (5 ml/g seed). When compared to extraction of macerated seeds, the leaching procedure released essentially all the 20HE available in the seeds (491 μg/g seed). The optimized quinoa leachate (QL), containing 0.86% 20HE, 1.00% total phytoecdysteroids, 2.59% flavonoid glycosides, 11.9% oil, and 20.4% protein, significantly lowered fasting blood glucose in obese, hyperglycemic mice. Leaching effectively releases and concentrates bioactive phytochemicals from quinoa seeds, providing an efficient means to produce a food-grade mixture that may be useful for anti-diabetic applications. PMID:24912714

  17. Physiological quality and seed respiration of primed Jatropha curcas seeds

    Directory of Open Access Journals (Sweden)

    Micheli Angelica Horbach

    2017-11-01

    Full Text Available ABSTRACT Seed deterioration is a natural and irreversible process. Nevertheless, seed priming with water and antioxidants can minimize oxidative damage in oilseeds, resulting in attenuation of seed deterioration. The objective of this assay was to evaluate seed priming on respiratory activity of Jatropha curcas submitted to accelerated aging. Seeds from two provenances (Janauba and Pedro J. Caballero were submitted to three priming treatments (control, immersion in deionized water, and with 750 µmol L-1 of ascorbic acid and treated for accelerated aging at 41 °C for 72 h. The results showed that the priming of J. curcas seeds promoted tolerance to accelerated aging. Primed seeds, with ascorbic acid from Janauba and deionized water from Pedro J. Caballero, resulted in a higher percentage of normal seedlings, and increased germination speed index and seed respiration. The decline of physiological quality of J. curcas seeds after accelerated aging is directly associated with a reduction in respiratory activity that is related to seed moisture content.

  18. New Methods in Non-Perturbative QCD

    Energy Technology Data Exchange (ETDEWEB)

    Unsal, Mithat [North Carolina State Univ., Raleigh, NC (United States)

    2017-01-31

    In this work, we investigate the properties of quantum chromodynamics (QCD), by using newly developing mathematics and physics formalisms. Almost all of the mass in the visible universe emerges from a quantum chromodynamics (QCD), which has a completely negligible microscopic mass content. An intimately related issue in QCD is the quark confinement problem. Answers to non-perturbative questions in QCD remained largely elusive despite much effort over the years. It is also believed that the usual perturbation theory is inadequate to address these kinds of problems. Perturbation theory gives a divergent asymptotic series (even when the theory is properly renormalized), and there are non-perturbative phenomena which never appear at any order in perturbation theory. Recently, a fascinating bridge between perturbation theory and non-perturbative effects has been found: a formalism called resurgence theory in mathematics tells us that perturbative data and non-perturbative data are intimately related. Translating this to the language of quantum field theory, it turns out that non-perturbative information is present in a coded form in perturbation theory and it can be decoded. We take advantage of this feature, which is particularly useful to understand some unresolved mysteries of QCD from first principles. In particular, we use: a) Circle compactifications which provide a semi-classical window to study confinement and mass gap problems, and calculable prototypes of the deconfinement phase transition; b) Resurgence theory and transseries which provide a unified framework for perturbative and non-perturbative expansion; c) Analytic continuation of path integrals and Lefschetz thimbles which may be useful to address sign problem in QCD at finite density.

  19. Initial conditions for hydrodynamics from weakly coupled pre-equilibrium evolution

    CERN Document Server

    Keegan, Liam; Mazeliauskas, Aleksas; Teaney, Derek

    2016-01-01

    We use effective kinetic theory, accurate at weak coupling, to simulate the pre-equilibrium evolution of transverse energy and flow perturbations in heavy-ion collisions. We provide a Green function which propagates the initial perturbations to the energy-momentum tensor at a time when hydrodynamics becomes applicable. With this map, the complete pre-thermal evolution from saturated nuclei to hydrodynamics can be modelled in a perturbatively controlled way.

  20. Numerical simulations of quiet Sun magnetic fields seeded by the Biermann battery

    Science.gov (United States)

    Khomenko, E.; Vitas, N.; Collados, M.; de Vicente, A.

    2017-08-01

    The magnetic fields of the quiet Sun cover at any time more than 90% of its surface and their magnetic energy budget is crucial to explain the thermal structure of the solar atmosphere. One of the possible origins of these fields is the action of the local dynamo in the upper convection zone of the Sun. Existing simulations of the local solar dynamo require an initial seed field and sufficiently high spatial resolution in order to achieve the amplification of the seed field to the observed values in the quiet Sun. Here we report an alternative model of seeding based on the action of the Bierman battery effect. This effect generates a magnetic field due to the local imbalances in electron pressure in the partially ionized solar plasma. We show that the battery effect self-consistently creates from zero an initial seed field of a strength of the order of micro G, and together with dynamo amplification allows the generation of quiet Sun magnetic fields of a similar strength to those from solar observations.

  1. Emergence of inflationary perturbations in the CSL model

    Energy Technology Data Exchange (ETDEWEB)

    Leon, Gabriel [Universidad de Buenos Aires, Ciudad Universitaria-PabI, Departamento de Fisica, Facultad de Ciencias Exactas y Naturales, Buenos Aires (Argentina); Bengochea, Gabriel R. [Instituto de Astronomia y Fisica del Espacio (IAFE), UBA-CONICET, Buenos Aires (Argentina)

    2016-01-15

    The inflationary paradigm is the most successful model that explains the observed spectrum of primordial perturbations. However, the precise emergence of such inhomogeneities and the quantum-to-classical transition of the perturbations has not yet reached a consensus among the community. The continuous spontaneous localization model (CSL), in the cosmological context, might be used to provide a solution to the mentioned issues by considering a dynamical reduction of the wave function. The CSL model has been applied to the inflationary universe before and different conclusions have been obtained. In this letter, we use a different approach to implement the CSL model during inflation. In particular, in addition to accounting for the quantum-to-classical transition, we use the CSL model to generate the primordial perturbations, that is, the dynamical evolution provided by the CSL model is responsible for the transition from a homogeneous and isotropic initial state to a final one lacking such symmetries. Our approach leads to results that can be clearly distinguished from preceding works. Specifically, the scalar and tensor power spectra are not time-dependent, and one retains the amplification mechanism of the CSL model. Moreover, our framework depends only on one parameter (the CSL parameter) and its value is consistent with cosmological and laboratory observations. (orig.)

  2. Cosmological perturbation theory and quantum gravity

    Energy Technology Data Exchange (ETDEWEB)

    Brunetti, Romeo [Dipartimento di Matematica, Università di Trento,Via Sommarive 14, 38123 Povo TN (Italy); Fredenhagen, Klaus [II Institute für Theoretische Physik, Universität Hamburg,Luruper Chaussee 149, 22761 Hamburg (Germany); Hack, Thomas-Paul [Institute für Theoretische Physik, Universität Leipzig,Brüderstr. 16, 04103 Leipzig (Germany); Pinamonti, Nicola [Dipartimento di Matematica, Università di Genova,Via Dodecaneso 35, 16146 Genova (Italy); INFN, Sezione di Genova,Via Dodecaneso 33, 16146 Genova (Italy); Rejzner, Katarzyna [Department of Mathematics, University of York,Heslington, York YO10 5DD (United Kingdom)

    2016-08-04

    It is shown how cosmological perturbation theory arises from a fully quantized perturbative theory of quantum gravity. Central for the derivation is a non-perturbative concept of gauge-invariant local observables by means of which perturbative invariant expressions of arbitrary order are generated. In particular, in the linearised theory, first order gauge-invariant observables familiar from cosmological perturbation theory are recovered. Explicit expressions of second order quantities are presented as well.

  3. Mathematical inference and control of molecular networks from perturbation experiments

    Science.gov (United States)

    Mohammed-Rasheed, Mohammed

    in order to affect the time evolution of molecular activity in a desirable manner. In this proposal, we address both the inference and control problems of GRNs. In the first part of the thesis, we consider the control problem. We assume that we are given a general topology network structure, whose dynamics follow a discrete-time Markov chain model. We subsequently develop a comprehensive framework for optimal perturbation control of the network. The aim of the perturbation is to drive the network away from undesirable steady-states and to force it to converge to a unique desirable steady-state. The proposed framework does not make any assumptions about the topology of the initial network (e.g., ergodicity, weak and strong connectivity), and is thus applicable to general topology networks. We define the optimal perturbation as the minimum-energy perturbation measured in terms of the Frobenius norm between the initial and perturbed networks. We subsequently demonstrate that there exists at most one optimal perturbation that forces the network into the desirable steady-state. In the event where the optimal perturbation does not exist, we construct a family of sub-optimal perturbations that approximate the optimal solution arbitrarily closely. In the second part of the thesis, we address the inference problem of GRNs from time series data. We model the dynamics of the molecules using a system of ordinary differential equations corrupted by additive white noise. For large-scale networks, we formulate the inference problem as a constrained maximum likelihood estimation problem. We derive the molecular interactions that maximize the likelihood function while constraining the network to be sparse. We further propose a procedure to recover weak interactions based on the Bayesian information criterion. For small-size networks, we investigated the inference of a globally stable 7-gene melanoma genetic regulatory network from genetic perturbation experiments. We considered five

  4. Evolution of the YABBY gene family in seed plants.

    Science.gov (United States)

    Finet, Cédric; Floyd, Sandra K; Conway, Stephanie J; Zhong, Bojian; Scutt, Charles P; Bowman, John L

    2016-01-01

    Members of the YABBY gene family of transcription factors in angiosperms have been shown to be involved in the initiation of outgrowth of the lamina, the maintenance of polarity, and establishment of the leaf margin. Although most of the dorsal-ventral polarity genes in seed plants have homologs in non-spermatophyte lineages, the presence of YABBY genes is restricted to seed plants. To gain insight into the origin and diversification of this gene family, we reconstructed the evolutionary history of YABBY gene lineages in seed plants. Our findings suggest that either one or two YABBY genes were present in the last common ancestor of extant seed plants. We also examined the expression of YABBY genes in the gymnosperms Ephedra distachya (Gnetales), Ginkgo biloba (Ginkgoales), and Pseudotsuga menziesii (Coniferales). Our data indicate that some YABBY genes are expressed in a polar (abaxial) manner in leaves and female cones in gymnosperms. We propose that YABBY genes already acted as polarity genes in the last common ancestor of extant seed plants. © 2016 Wiley Periodicals, Inc.

  5. Evaluation of Wheat (Triticum aestivum, L. Seed Quality of Certified Seed and Farm-Saved Seed in Three Provinces of Iran

    Directory of Open Access Journals (Sweden)

    Khazaei Fardin

    2016-06-01

    Full Text Available The objective of this study was to study the seed quality aspects of wheat (Triticum aestivum L. and the extent of weed seed contamination present in wheat seeds produced in different regions of Iran. Four districts (cities, each including 12 fields (six certified seed fields and six farm-saved seed fields, were selected in each regions (provinces. One kilogram of the wheat seed sample was collected from each field for analysis in the laboratory. Wheat seeding was commonly done by farm-saved seed sourced from within the farm due to the high costs of certified seeds purchased from outside sources, followed by the low seed quality. The use of a farm-saved seed resulted in a higher germination rate and a lower mean time to germination compared with another system. The more positive temperatures experienced by mother plants could decrease the number of normal seedling and seedling length vigor index. Generally there was virtually no difference about physiological quality between certified seed and farm-saved seed sector that is related to lower quality of certified seed. The certified produced seeds had the lower number of weed seed, species and genus before and after cleaning. The highest seed purity and 1000 seed weight was obtained from the certified seed production system. The need for cleaning the farm-saved seed samples before sowing is one of the important findings of this survey.

  6. Consistent scalar and tensor perturbation power spectra in single fluid matter bounce with dark energy era

    Science.gov (United States)

    Bacalhau, Anna Paula; Pinto-Neto, Nelson; Vitenti, Sandro Dias Pinto

    2018-04-01

    We investigate cosmological scenarios containing one canonical scalar field with an exponential potential in the context of bouncing models, in which the bounce happens due to quantum cosmological effects. The only possible bouncing solutions in this scenario (discarding an infinitely fine-tuned exception) must have one and only one dark energy phase, occurring either in the contracting era or in the expanding era. Hence, these bounce solutions are necessarily asymmetric. Naturally, the more convenient solution is the one in which the dark energy phase happens in the expanding era, in order to be a possible explanation for the current accelerated expansion indicated by cosmological observations. In this case, one has the picture of a Universe undergoing a classical dust contraction from very large scales, the initial repeller of the model, moving to a classical stiff-matter contraction near the singularity, which is avoided due to the quantum bounce. The Universe is then launched to a dark energy era, after passing through radiation- and dust-dominated phases, finally returning to the dust expanding phase, the final attractor of the model. We calculate the spectral indices and amplitudes of scalar and tensor perturbations numerically, considering the whole history of the model, including the bounce phase itself, without making any approximation nor using any matching condition on the perturbations. As the background model is necessarily dust dominated in the far past, the usual adiabatic vacuum initial conditions can be easily imposed in this era. Hence, this is a cosmological model in which the presence of dark energy behavior in the Universe does not turn the usual vacuum initial conditions prescription for cosmological perturbation in bouncing models problematic. Scalar and tensor perturbations end up being almost scale invariant, as expected. The background parameters can be adjusted, without fine-tunings, to yield the observed amplitude for scalar

  7. Seed dormancy and seed longevity: from genetic variation to gene identification

    NARCIS (Netherlands)

    Nguyen, T.P.

    2014-01-01

    Seed dormancy and seed longevity are the most important survival traits in the soil seed bank. Both traits are induced during seed maturation and evolved to assure seed survival during environmental conditions that cannot support the regular course of life. Seed dormancy is related to the timing of

  8. Influence of Fungicides Application and Seed Processing on Sunflower Seed Quality

    OpenAIRE

    Šimić, Branimir; Svitlica, Brankica; Ćosić, Jasenka; Andrić, Luka; Rozman, Vlatka; Postić, Jelena; Liović, Ivica

    2009-01-01

    The aim of the research was to determine influence of methods of seed processing and application of fungicides on mass of 1000 seeds, intergrowth energy and seed germination of sunflower hybrids ‘Favorit’ and ‘Apolon’ in 2005 and 2006. Selected untreated seeds of both sunflower hybrids (control) had a minimal mass of 1000 seeds (55-59 g), intergrowth energy (18-37 %) and seed germination (39-52 %). In both years of research maximal seed quality, mass of 1000 seeds (67-69 g), intergrowth energ...

  9. Perturbations i have Known and Loved

    Science.gov (United States)

    Field, Robert W.

    2011-06-01

    A spectroscopic perturbation is a disruption of a ^1Σ-^1Σ-like regular pattern that can embody level-shifts, extra lines, and intensity anomalies. Once upon a time, when a band was labeled ``perturbed,'' it was considered worthless because it could at best yield molecular constants unsuited for archival tables. Nevertheless, a few brave spectroscopists, notably Albin Lagerqvist and Richard Barrow, collected perturbations because they knew that the pattern of multiple perturbations formed an intricate puzzle that would eventually reveal the presence and electronic symmetry of otherwise unobservable electronic states. There are many kinds of patterns of broken patterns. In my PhD thesis I showed how to determine absolute vibrational assignments for the perturber from patterns among the observed values of perturbation matrix elements. When a ^3Π state is perturbed, its six (Ω, parity) components capture a pattern of level shifts and intensity anomalies that reveals more about the nature of the perturber than a simple perturbation of the single component of a ^1Σ state. In perturbation-facilitated OODR, a perturbed singlet level acts as a spectroscopic doorway through which the entire triplet manifold may be systematically explored. For polyatomic molecule vibrations, a vibrational polyad (a group of mutually perturbing vibrational levels, among which the perturbation matrix elements are expected to follow harmonic oscillator scaling rules) can contain more components than a ^3Π state and intrapolyad patterns can be exquisitely sensitive not merely to the nature of an interloper within the polyad but also to the eigenvector character of the vibronic state from which the polyad is viewed. Variation of scaled polyad interaction parameters from one polyad to the next, a pattern of patterns, can signal proximity to an isomerization barrier. Everything in Rydberg-land seems to scale as N⋆-3, yet a trespassing valence state causes all scaling and propensity rules go

  10. Comparison of secondary organic aerosol formation from toluene on initially wet and dry ammonium sulfate particles at moderate relative humidity

    Science.gov (United States)

    Liu, Tengyu; Huang, Dan Dan; Li, Zijun; Liu, Qianyun; Chan, ManNin; Chan, Chak K.

    2018-04-01

    The formation of secondary organic aerosol (SOA) has been widely studied in the presence of dry seed particles at low relative humidity (RH). At higher RH, initially dry seed particles can exist as wet particles due to water uptake by the seeds as well as the SOA. Here, we investigated the formation of SOA from the photooxidation of toluene using an oxidation flow reactor in the absence of NOx under a range of OH exposures on initially wet or dry ammonium sulfate (AS) seed particles at an RH of 68 %. The ratio of the SOA yield on wet AS seeds to that on dry AS seeds, the relative SOA yield, decreased from 1.31 ± 0.02 at an OH exposure of 4.66 × 1010 molecules cm-3 s to 1.01 ± 0.01 at an OH exposure of 5.28 × 1011 molecules cm-3 s. This decrease may be due to the early deliquescence of initially dry AS seeds after being coated by highly oxidized toluene-derived SOA. SOA formation lowered the deliquescence RH of AS and resulted in the uptake of water by both AS and SOA. Hence the initially dry AS seeds contained aerosol liquid water (ALW) soon after SOA formed, and the SOA yield and ALW approached those of the initially wet AS seeds as OH exposure and ALW increased, especially at high OH exposure. However, a higher oxidation state of the SOA on initially wet AS seeds than that on dry AS seeds was observed at all levels of OH exposure. The difference in mass fractions of m / z 29, 43 and 44 of SOA mass spectra, obtained using an aerosol mass spectrometer (AMS), indicated that SOA formed on initially wet seeds may be enriched in earlier-generation products containing carbonyl functional groups at low OH exposures and later-generation products containing acidic functional groups at high exposures. Our results suggest that inorganic dry seeds become at least partially deliquesced particles during SOA formation and hence that ALW is inevitably involved in the SOA formation at moderate RH. More laboratory experiments conducted with a wide variety of SOA precursors

  11. Linear analysis on the growth of non-spherical perturbations in supersonic accretion flows

    Energy Technology Data Exchange (ETDEWEB)

    Takahashi, Kazuya; Yamada, Shoichi, E-mail: ktakahashi@heap.phys.waseda.ac.jp [Advanced Research Institute for Science and Engineering, Waseda University, 3-4-1 Okubo, Shinjuku 169-8555 (Japan)

    2014-10-20

    We analyzed the growth of non-spherical perturbations in supersonic accretion flows. We have in mind an application to the post-bounce phase of core-collapse supernovae (CCSNe). Such non-spherical perturbations have been suggested by a series of papers by Arnett, who has numerically investigated violent convections in the outer layers of pre-collapse stars. Moreover, Couch and Ott demonstrated in their numerical simulations that such perturbations may lead to a successful supernova even for a progenitor that fails to explode without fluctuations. This study investigated the linear growth of perturbations during the infall onto a stalled shock wave. The linearized equations are solved as an initial and boundary value problem with the use of a Laplace transform. The background is a Bondi accretion flow whose parameters are chosen to mimic the 15 M {sub ☉} progenitor model by Woosley and Heger, which is supposed to be a typical progenitor of CCSNe. We found that the perturbations that are given at a large radius grow as they flow down to the shock radius; the density perturbations can be amplified by a factor of 30, for example. We analytically show that the growth rate is proportional to l, the index of the spherical harmonics. We also found that the perturbations oscillate in time with frequencies that are similar to those of the standing accretion shock instability. This may have an implication for shock revival in CCSNe, which will be investigated in our forthcoming paper in more detail.

  12. Particle linear theory on a self-gravitating perturbed cubic Bravais lattice

    International Nuclear Information System (INIS)

    Marcos, B.

    2008-01-01

    Discreteness effects are a source of uncontrolled systematic errors of N-body simulations, which are used to compute the evolution of a self-gravitating fluid. We have already developed the so-called ''particle linear theory''(PLT), which describes the evolution of the position of self-gravitating particles located on a perturbed simple cubic lattice. It is the discrete analogue of the well-known (Lagrangian) linear theory of a self-gravitating fluid. Comparing both theories permits us to quantify precisely discreteness effects in the linear regime. It is useful to develop the PLT also for other perturbed lattices because they represent different discretizations of the same continuous system. In this paper we detail how to implement the PLT for perturbed cubic Bravais lattices (simple, body, and face-centered) in a cubic simulation box. As an application, we will study the discreteness effects--in the linear regime--of N-body simulations for which initial conditions have been set up using these different lattices.

  13. Arabidopsis plastidial folylpolyglutamate synthetase is required for seed reserve accumulation and seedling establishment in darkness.

    Directory of Open Access Journals (Sweden)

    Hongyan Meng

    Full Text Available Interactions among metabolic pathways are important in plant biology. At present, not much is known about how folate metabolism affects other metabolic pathways in plants. Here we report a T-DNA insertion mutant (atdfb-3 of the plastidial folylpolyglutamate synthetase gene (AtDFB was defective in seed reserves and skotomorphogenesis. Lower carbon (C and higher nitrogen (N content in the mutant seeds than that of the wild type were indicative of an altered C and N partitioning capacity. Higher levels of organic acids and sugars were detected in the mutant seeds compared with the wild type. Further analysis revealed that atdfb-3 seeds contained less total amino acids and individual Asn and Glu as well as NO3-. These results indicate significant changes in seed storage in the mutant. Defects in hypocotyl elongation were observed in atdfb-3 in darkness under sufficient NO3- conditions, and further enhanced under NO3- limited conditions. The strong expression of AtDFB in cotyledons and hypocotyl during early developmental stage was consistent with the mutant sensitivity to limited NO3- during a narrow developmental window. Exogenous 5-formyl-tetrahydrofolate completely restored the hypocotyl length in atdfb-3 seedlings with NO3- as the sole N source. Further study demonstrated that folate profiling and N metabolism were perturbed in atdfb-3 etiolated seedlings. The activity of enzymes involved in N reduction and assimilation was altered in atdfb-3. Taken together, these results indicate that AtDFB is required for seed reserves, hypocotyl elongation and N metabolism in darkness, providing novel insights into potential associations of folate metabolism with seed reserve accumulation, N metabolism and hypocotyl development in Arabidopsis.

  14. The effect of hydrostatic vs. shock pressure treatment of plant seeds

    International Nuclear Information System (INIS)

    Mustey, A; Leighs, J A; Appleby, G J; Wood, D C; Hazael, R; McMillan, P F; Hazell, P J

    2014-01-01

    The hydrostatic pressure and shock response of plant seeds has been investigated antecedently, primarily driven by interest in reducing bacterial contamination of crops and the theory of panspermia, respectively. However, comparisons have not previously been made between these two methods ofapplying pressure to plant seeds. Here such a comparison has been undertaken based on the premise that any correlations in collected data may provide a route to inform understanding of damage mechanisms in the seeds under test. In this work two varieties of plant seeds were subjected to hydrostatic pressure via a non-end-loaded piston cylinder setup and shock compression via employment of a 50 mm bore, single stage gas gun using the flyer plate technique. Results from germination tests of recovered seed samples have been compared and contrasted, and initial conclusions made regarding causes of trends in the resultant data-set. Data collected has shown that cress seeds are extremely resilient to static loading, whereas the difference in the two forms of loading is negligible for lettuce seeds. Germination time has been seen to extend dramatically following static loading of cress seeds to greater than 0.4 GPa. In addition, the cut-off pressure previously seen to cause 0% germination in dynamic experiments performed on cress seeds has now also been seen in lettuce seeds.

  15. The effect of hydrostatic vs. shock pressure treatment of plant seeds

    Science.gov (United States)

    Mustey, A.; Leighs, J. A.; Appleby-Thomas, G. J.; Wood, D. C.; Hazael, R.; McMillan, P. F.; Hazell, P. J.

    2014-05-01

    The hydrostatic pressure and shock response of plant seeds has been investigated antecedently, primarily driven by interest in reducing bacterial contamination of crops and the theory of panspermia, respectively. However, comparisons have not previously been made between these two methods ofapplying pressure to plant seeds. Here such a comparison has been undertaken based on the premise that any correlations in collected data may provide a route to inform understanding of damage mechanisms in the seeds under test. In this work two varieties of plant seeds were subjected to hydrostatic pressure via a non-end-loaded piston cylinder setup and shock compression via employment of a 50 mm bore, single stage gas gun using the flyer plate technique. Results from germination tests of recovered seed samples have been compared and contrasted, and initial conclusions made regarding causes of trends in the resultant data-set. Data collected has shown that cress seeds are extremely resilient to static loading, whereas the difference in the two forms of loading is negligible for lettuce seeds. Germination time has been seen to extend dramatically following static loading of cress seeds to greater than 0.4 GPa. In addition, the cut-off pressure previously seen to cause 0% germination in dynamic experiments performed on cress seeds has now also been seen in lettuce seeds.

  16. Investigating Seed Longevity of Big Sagebrush (Artemisia tridentata)

    Science.gov (United States)

    Wijayratne, Upekala C.; Pyke, David A.

    2009-01-01

    from each site, as well as several environmental variables, were used to evaluate seed viability within the context of habitat variation. Initial viability of seeds used in the seed retrieval experiment was 81 and 92 percent for mountain and Wyoming big sagebrush, respectively. After remaining in the field for 24 months, buried Wyoming big sagebrush seeds retained 28-58 percent viability,11-23 percent of seeds under litter remained viable, and no seeds remained viable on the surface (estimates are 95-percent confidence intervals). The odds of remaining viable did not change from 12 to 24 months. However, after 24 months the odds of seeds beneath litter being viable decreased to 75 percent of the odds of viability at 12 months. Similar to Wyoming big sagebrush, buried seeds of mountain big sagebrush were 31-68 percent viable, seeds under litter retained 10-22 percent of their viability, and no surface seeds were viable after 24 months. Both subspecies of big sagebrush had some portion of seed that remained viable for more than one growing season provided they were buried or under litter. Although seeds beneath litter may remain viable in intact communities, seeds are susceptible to incineration during fires. Nine months after seed dispersal, seed bank estimates for Wyoming big sagebrush ranged from 19 to 49 viable seeds/m2 in litter samples and 19-57 viable seeds/m2 in soil samples (95-percent confidence interval). For mountain big sagebrush, estimates were 27-75 viable seeds/m2 in litter samples and 54-139 viable seeds/m2 in soil (95-percent confidence interval). The number of viable seeds present in the seed bank 9 months after seed dispersal was not significantly different from the number present immediately after seed dispersal. Seed viability was highest in mountain big sagebrush sites for seeds on the surface and beneath litter, but decreased after one season. Buried seeds of both subspecies were in equal abundances and may be insulated from the effect

  17. Farmer’s seed sources and seed quality: 2. seed health

    NARCIS (Netherlands)

    Bishaw, Z.; Struik, P.C.; Gastel, van A.J.G.

    2013-01-01

    The study assessed the health quality of wheat (Triticum aestivum L.) and barley (Hordeum vulgare L.) seed samples collected from formal and informal sector in Ethiopia and Syria. In Ethiopia, several seed-borne fungi were found on wheat samples: Cochliobolus sativum, Fusarium avenaceum, F.

  18. PHYSIOLOGICAL QUALITY OF Araucaria angustifolia (Bertol. Kuntze SEEDS SUBMITTED TO DIFFERENT STORAGE CONDITIONS AND ESCARIFICATION

    Directory of Open Access Journals (Sweden)

    Álvaro Valente Caçola

    2010-08-01

    Full Text Available The seeds of Araucaria angustifolia (Bertol. Kuntze are recalcitrants and, therefore, they lose rapidly the viability after the harvest, limiting their use for nursery production of seedlings. This work was carried out to investigate the effects of cold storage duration, conservation method, and escarification on germination and vigour of seeds of Araucaria angustifolia. The seeds were cold stored (0-1oC/90-95% RH for 0, 60, 120, and 180 days, under normal air condictions (NA, modified atmosphere (MA, and controlled atmosphere (CA storage. For each cold storage duration, after removal from cold storage, the seeds were submitted or not to scarification (by cutting a small portion of the apical seed tegument, avoiding the damage of the endosperm, letting the germinate in a chamber with controlled environment, in plastic trays filled with vermiculite, for 60 days. The experiment followed the completely randomized factorial design (4x3x2, with four cold storage durations (0, 60, 120, and 180 days, three storage methods (NA, MA, and CA, with or without escarification, and four replicates. There was a good preservation of physiological quality for seeds submitted to different conservation methods in cold storage along the 180-day period. However, there was a faster germination and initial growth of seedlings for seeds left in cold storage for 60 days than in seeds assessed at harvest or left in cold storage for 120-180 days. The NA storage of seeds in perfurated plastic bags was as efficient as MA and CA storage to preserve seeds quality. Seeds scarification increased vigor and promoted seedlings initial growth of Araucaria angustifolia after being removed from cold storage.

  19. [Dynamics of seed rain of Tripterygium hypoglaucum and soil seed bank].

    Science.gov (United States)

    Zhang, Zhi-Wei; Wei, Yong-Sheng; Liu, Xiang; Su, Shu; Qu, Xian-You; Wang, Chang-Hua

    2017-11-01

    Tripterygium hypoglaucum is an endangered species in arid areas of Xiannvshan Chongqing, China. The dynamic characteristics of seed rain and soil seed bank of T. hypoglaucum were studied in this paper.Results showed that T. hypoglaucum years of mature seeds distribution number up to October; the seed rain occurred from the last ten-day of September to in the first ten-day of November and the peak of scattered seed rain concentrated in the October.The numbers of soil seed bank at 2-5 cm soil layer,mainly concentrated in the 1.5-3.5 m range. T. hypoglaucum seeds to the wind as a force for transmission, the transmission ability is strong, but in the process of natural reproduction, full mature seed rate is low, the soil seed bank seeds seed short-lived factors these were unfavorable for the natural reproduction of T. hypoglaucum population. Copyright© by the Chinese Pharmaceutical Association.

  20. [Procedure of seed quality testing and seed grading standard of Prunus humilis].

    Science.gov (United States)

    Wen, Hao; Ren, Guang-Xi; Gao, Ya; Luo, Jun; Liu, Chun-Sheng; Li, Wei-Dong

    2014-11-01

    So far there exists no corresponding quality test procedures and grading standards for the seed of Prunus humilis, which is one of the important source of base of semen pruni. Therefor we set up test procedures that are adapt to characteristics of the P. humilis seed through the study of the test of sampling, seed purity, thousand-grain weight, seed moisture, seed viability and germination percentage. 50 cases of seed specimens of P. humilis tested. The related data were analyzed by cluster analysis. Through this research, the seed quality test procedure was developed, and the seed quality grading standard was formulated. The seed quality of each grade should meet the following requirements: for first grade seeds, germination percentage ≥ 68%, thousand-grain weight 383 g, purity ≥ 93%, seed moisture ≤ 5%; for second grade seeds, germination percentage ≥ 26%, thousand-grain weight ≥ 266 g, purity ≥ 73%, seed moisture ≤9%; for third grade seeds, germination percentage ≥ 10%, purity ≥ 50%, thousand-grain weight ≥ 08 g, seed moisture ≤ 13%.

  1. Investigation of coagulation activity of natural coagulants from seeds of different leguminose species

    Directory of Open Access Journals (Sweden)

    Šćiban Marina B.

    2005-01-01

    Full Text Available The ability of seeds of plants: Phaseolus vulgaris, Robinia pseudoacacia Ceratonia siliqua and Amorpha fruticosa, to act as natural coagulants was tested using synthetic turbid water. This water was prepared by adding kaolin into tap water, just before the test. Active components were extracted from ground seeds with distilled water. The coagulation ability of this extract was assessed by the use of standard jar test measurements in water with various initial turbidity. Investigation of these natural coagulants was confirmed their positive coagulation activity. Of all plants that have been examined, the seed extract from Ceratonia siliqua appeared to be one of the most effective coagulants for water treatment. A dose of 20 mg/l of this coagulant resulted in 100% coagulation activity for clarification of water with 17.5 NTU initial turbidity.

  2. Different modes of hydrogen peroxide action during seed germination

    Directory of Open Access Journals (Sweden)

    Łukasz eWojtyla

    2016-02-01

    Full Text Available Hydrogen peroxide was initially recognized as a toxic molecule that causes damage at different levels of cell organization and thus losses in cell viability. From the 1990s, the role of hydrogen peroxide as a signaling molecule in plants has also been discussed. The beneficial role of H2O2 as a central hub integrating signaling network in response to biotic and abiotic stress and during developmental processes is now well established. Seed germination is the most pivotal phase of the plant life cycle, affecting plant growth and productivity. The function of hydrogen peroxide in seed germination and seed aging has been illustrated in numerous studies; however, the exact role of this molecule remains unknown. This review evaluates evidence that shows that H2O2 functions as a signaling molecule in seed physiology in accordance with the known biology and biochemistry of H2O2. The importance of crosstalk between hydrogen peroxide and a number of signaling molecules, including plant phytohormones such as abscisic acid, gibberellins and ethylene and reactive molecules such as nitric oxide and hydrogen sulfide acting on cell communication and signaling during seed germination, is highlighted. The current study also focuses on the detrimental effects of H2O2 on seed biology, i.e., seed aging that leads to a loss of germination efficiency. The dual nature of hydrogen peroxide as a toxic molecule on one hand and as a signal molecule on the other is made possible through the precise spatial and temporal control of its production and degradation. Levels of hydrogen peroxide in germinating seeds and young seedlings can be modulated via pre-sowing seed priming/conditioning. This rather simple method is shown to be a valuable tool for improving seed quality and for enhancing seed stress tolerance during post-priming germination. In this review, we outline how seed priming/conditioning affects the integrative role of hydrogen peroxide in seed germination and

  3. On the initial regime of pre-big bang cosmology

    Energy Technology Data Exchange (ETDEWEB)

    Gasperini, M., E-mail: gasperini@ba.infn.it [Dipartimento di Fisica, Università di Bari, Via G. Amendola 173, 70126 Bari (Italy)

    2017-09-01

    The production of a background of super-horizon curvature perturbations with the appropriate (red) spectrum needed to trigger the cosmic anisotropies observed on large scales is associated, in the context of pre-big bang inflation, with a phase of growing string coupling. The extension towards the past of such a phase is not limited in time by the dynamical backreaction of the quantum perturbations of the cosmological geometry and of its sources. A viable, slightly red spectrum of scalar perturbations can thus be the output of an asymptotic, perturbative regime which is well compatible with an initial string-vacuum state satisfying the postulate of 'Asymptotic Past Triviality'.

  4. Optimal random perturbations for stochastic approximation using a simultaneous perturbation gradient approximation

    DEFF Research Database (Denmark)

    Sadegh, Payman; Spall, J. C.

    1998-01-01

    simultaneous perturbation approximation to the gradient based on loss function measurements. SPSA is based on picking a simultaneous perturbation (random) vector in a Monte Carlo fashion as part of generating the approximation to the gradient. This paper derives the optimal distribution for the Monte Carlo...

  5. The effect of hydrostatic vs. shock pressure treatment on plant seeds

    Science.gov (United States)

    Mustey, Adrian; Leighs, James; Appleby-Thomas, Gareth; Wood, David; Hazael, Rachael; McMillan, Paul; Hazell, Paul

    2013-06-01

    The hydrostatic pressure and shock response of plant seeds have both been previously investigated (primarily driven by an interest in reducing bacterial contamination of crops and the theory of panspermia respectively). However, comparisons have not previously been made between these two methods of applying pressure to plant seeds. Here such a comparison has been undertaken based on the premise that any correlations in such data may provide a route to inform understanding of damage mechanisms in the seeds under test. In this work two varieties of plant seeds were subjected to hydrostatic pressure via a non-end-loaded piston cylinder set-up and shock compression via employment of a 50-mm bore, single stage gas gun using the flyer-plate technique. Results from germination tests of recovered seed samples have been compared and contrasted, and initial conclusions made regarding causes of trends in the resultant data-set.

  6. Perturbation analysis of spontaneous action potential initiation by stochastic ion channels

    KAUST Repository

    Keener, James P.; Newby, Jay M.

    2011-01-01

    A stochastic interpretation of spontaneous action potential initiation is developed for the Morris-Lecar equations. Initiation of a spontaneous action potential can be interpreted as the escape from one of the wells of a double well potential

  7. Disformal transformation of cosmological perturbations

    Directory of Open Access Journals (Sweden)

    Masato Minamitsuji

    2014-10-01

    Full Text Available We investigate the gauge-invariant cosmological perturbations in the gravity and matter frames in the general scalar–tensor theory where two frames are related by the disformal transformation. The gravity and matter frames are the extensions of the Einstein and Jordan frames in the scalar–tensor theory where two frames are related by the conformal transformation, respectively. First, it is shown that the curvature perturbation in the comoving gauge to the scalar field is disformally invariant as well as conformally invariant, which gives the predictions from the cosmological model where the scalar field is responsible both for inflation and cosmological perturbations. Second, in case that the disformally coupled matter sector also contributes to curvature perturbations, we derive the evolution equations of the curvature perturbation in the uniform matter energy density gauge from the energy (nonconservation in the matter sector, which are independent of the choice of the gravity sector. While in the matter frame the curvature perturbation in the uniform matter energy density gauge is conserved on superhorizon scales for the vanishing nonadiabatic pressure, in the gravity frame it is not conserved even if the nonadiabatic pressure vanishes. The formula relating two frames gives the amplitude of the curvature perturbation in the matter frame, once it is evaluated in the gravity frame.

  8. Disformal transformation of cosmological perturbations

    International Nuclear Information System (INIS)

    Minamitsuji, Masato

    2014-01-01

    We investigate the gauge-invariant cosmological perturbations in the gravity and matter frames in the general scalar–tensor theory where two frames are related by the disformal transformation. The gravity and matter frames are the extensions of the Einstein and Jordan frames in the scalar–tensor theory where two frames are related by the conformal transformation, respectively. First, it is shown that the curvature perturbation in the comoving gauge to the scalar field is disformally invariant as well as conformally invariant, which gives the predictions from the cosmological model where the scalar field is responsible both for inflation and cosmological perturbations. Second, in case that the disformally coupled matter sector also contributes to curvature perturbations, we derive the evolution equations of the curvature perturbation in the uniform matter energy density gauge from the energy (non)conservation in the matter sector, which are independent of the choice of the gravity sector. While in the matter frame the curvature perturbation in the uniform matter energy density gauge is conserved on superhorizon scales for the vanishing nonadiabatic pressure, in the gravity frame it is not conserved even if the nonadiabatic pressure vanishes. The formula relating two frames gives the amplitude of the curvature perturbation in the matter frame, once it is evaluated in the gravity frame

  9. Perturbative odderon in the dipole model

    Energy Technology Data Exchange (ETDEWEB)

    Kovchegov, Yuri V.; Szymanowski, Lech; Wallon, Samuel

    2004-04-29

    We show that, in the framework of Mueller's dipole model, the perturbative QCD odderon is described by the dipole model equivalent of the BFKL equation with a C-odd initial condition. The eigenfunctions and eigenvalues of the odderon solution are the same as for the dipole BFKL equation and are given by the functions E{sup n,{nu}} and {chi}(n,{nu}) correspondingly, where the C-odd initial condition allows only for odd values of n. The leading high-energy odderon intercept is given by {alpha}{sub odd}-1=((2{alpha}{sub s}N{sub c})/({pi})){chi}(n=1,{nu}=0)=0 in agreement with the solution found by Bartels, Lipatov and Vacca. We proceed by writing down an evolution equation for the odderon including the effects of parton saturation. We argue that saturation makes the odderon solution a decreasing function of energy.

  10. Quantum inflaton, primordial perturbations, and CMB fluctuations

    International Nuclear Information System (INIS)

    Cao, F.J.; Vega, H.J. de; Sanchez, N.G.

    2004-01-01

    We compute the primordial scalar, vector and tensor metric perturbations arising from quantum field inflation. Quantum field inflation takes into account the nonperturbative quantum dynamics of the inflaton consistently coupled to the dynamics of the (classical) cosmological metric. For chaotic inflation, the quantum treatment avoids the unnatural requirements of an initial state with all the energy in the zero mode. For new inflation it allows a consistent treatment of the explosive particle production due to spinodal instabilities. Quantum field inflation (under conditions that are the quantum analog of slow-roll) leads, upon evolution, to the formation of a condensate starting a regime of effective classical inflation. We compute the primordial perturbations taking the dominant quantum effects into account. The results for the scalar, vector and tensor primordial perturbations are expressed in terms of the classical inflation results. For a N-component field in a O(N) symmetric model, adiabatic fluctuations dominate while isocurvature or entropy fluctuations are negligible. The results agree with the current Wilkinson Microwave Anisotropy Probe observations and predict corrections to the power spectrum in classical inflation. Such corrections are estimated to be of the order of (m 2 /NH 2 ), where m is the inflaton mass and H the Hubble constant at the moment of horizon crossing. An upper estimate turns to be about 4% for the cosmologically relevant scales. This quantum field treatment of inflation provides the foundations to the classical inflation and permits to compute quantum corrections to it

  11. Control of DNA synthesis in inhibited and activated Agrostemma githago seeds

    Energy Technology Data Exchange (ETDEWEB)

    Hecker, M [Sektion Biologie, FG Algemeine Botanik und Pflanzenphysiologie, Universitaet Greifswald (German Democratic Republic)

    1975-01-01

    The relationships between DNA synthesis and germination capacity of Agrostemma seeds had been studied. Protein synthesis and RNA synthesis were activated at the very beginning of imbibition, whereas DNA synthesis started in the second part of the imbibition phase. Agrostemma seeds inhibited by higher temperature (30 degC), or aged seeds with a low germination capacity were characterized by a significantly reduced protein synthesis. DNA synthesis was also reduced. The inhibition of the protein synthesis of Agrostemma embryos fed with cycloheximide or actinomycin D caused a depression of DNA synthesis. The results indicated that the initiation of DNA synthesis of imbibing Agrostemma seeds depended on the synthesis of special proteins. Abscisic acid inhibited the growth as well as DNA synthesis of isolated Agrostemma embryos. Nitomycin inhibited germination and DNA synthesis to the same extent. Dormant seeds with an undiminished intensity of protein synthesis also showed a reduced incorporation of /sup 3/H-thymidine by DNA. It is suggested that DNA synthesis of imbibed seeds, which is a necessary prerequisite for the radicle protrusion, was involved in the mechanism of ripening of the Agrostemma seeds.

  12. Control of DNA synthesis in inhibited and activated Agrostemma githago seeds

    International Nuclear Information System (INIS)

    Hecker, M.

    1975-01-01

    The relationships between DNA synthesis and germination capacity of Agrostemma seeds had been studied. Protein synthesis and RNA synthesis were activated at the very beginning of imbibition, whereas DNA synthesis started in the second part of the imbibition phase. Agrostemma seeds inhibited by higher temperature (30 degC), or aged seeds with a low germination capacity were characterized by a significantly reduced protein synthesis. DNA synthesis was also reduced. The inhibition of the protein synthesis of Agrostemma embryos fed with cycloheximide or actinomycin D caused a depression of DNA synthesis. The results indicated that the initiation of DNA synthesis of imbibing Agrostemma seeds depended on the synthesis of special proteins. Abscisic acid inhibited the growth as well as DNA synthesis of isolated Agrostemma embryos. Nitomycin inhibited germination and DNA synthesis to the same extent. Dormant seeds with an undiminished intensity of protein synthesis also showed a reduced incorporation of 3 H-thymidine by DNA. It is suggested that DNA synthesis of imbibed seeds, which is a necessary prerequisite for the radicle protrusion, was involved in the mechanism of ripening of the Agrostemma seeds. (author)

  13. Size, physiological quality, and green seed occurrence influenced by seeding rate in soybeans

    Directory of Open Access Journals (Sweden)

    André Sampaio Ferreira

    2017-05-01

    Full Text Available The seeding rate influences the intraspecific competition, which might affect the development and quality of seeds in soybean. However, the impact of seeding rate on the physical and physiological qualities of soybean seeds needs to be better elucidated. This study aimed to evaluate the effects of soybean plant density on the seed size as well as the effects of the interaction between the plant density and seed size on the seed mass, green seed occurence, and physiological seed quality. The experiments were carried out in the growing seasons of the years 2013/14 and 2014/15 in a Latossolo Vermelho distroférrico, under a randomized complete block design, using the NK 7059 RR cultivar with six replications. Four plant densities (150, 300, 440, and 560 thousand viable seeds ha–1 were evaluated. After the classification of seeds into four sizes, using a set of sieves, a 4 ×4 factorial scheme was used for the statistical analysis of the four plant densities and four seed sizes. The seed samples were evaluated for the seed mass, green seed percentage, germination, and vigor. Under thermal and water stress during seed development, an increase in the seeding rate led to a reduction in the green seed occurrence and an increase in the seed size and mass. However, in the absence of thermal and water stress, the seed size and mass were not altered by the seeding rate and, there was no occurrence of green seeds.

  14. Extraction and the Fatty Acid Profile of Rosa acicularis Seed Oil.

    Science.gov (United States)

    Du, Huanan; Zhang, Xu; Zhang, Ruchun; Zhang, Lu; Yu, Dianyu; Jiang, Lianzhou

    2017-12-01

    Rosa acicularis seed oil was extracted from Rosa acicularis seeds by the ultrasonic-assisted aqueous enzymatic method using cellulase and protease. Based on a single experiment, Plackett-Burman design was applied to ultrasonic-assisted aqueous enzymatic extraction of wild rose seed oil. The effects of enzyme amount, hydrolysis temperature and initial pH on total extraction rate of wild rose seed oil was studied by using Box-Behnken optimize methodology. Chemical characteristics of a sample of Rosa acicularis seeds and Rosa acicularis seed oil were characterized in this work. The tocopherol content was 200.6±0.3 mg/100 g oil. The Rosa acicularis seed oil was rich in linoleic acid (56.5%) and oleic acid (34.2%). The saturated fatty acids included palmitic acid (4%) and stearic acid (2.9%). The major fatty acids in the sn-2 position of triacylglycerol in Rosa acicularis oil were linoleic acid (60.6%), oleic acid (33.6%) and linolenic acid (3.2%). According to the 1,3-random-2-random hypothesis, the dominant triacylglycerols were LLL (18%), LLnL (1%), LLP (2%), LOL (10%), LLSt (1.2%), PLP (0.2%), LLnP (0.1%), LLnO (0.6%) and LOP (1.1%). This work could be useful for developing applications for Rosa acicularis seed oil.

  15. Numerical simulation of increasing initial perturbations of a bubble in the bubble–shock interaction problem

    Energy Technology Data Exchange (ETDEWEB)

    Korneev, Boris [Moscow Institute of Physics and Technology, 9 Institutsky lane, Dolgoprudny 141700 (Russian Federation); Levchenko, Vadim, E-mail: boris.korneev@phystech.edu [Keldysh Institute of Applied Mathematics, 4 Miusskaya square, Moscow 125047 (Russian Federation)

    2016-12-15

    A set of numerical experiments on the interaction between a planar shock wave and a spherical bubble with a slightly perturbed surface is considered. Spectral analysis of the instability growth is carried out and three-dimensional Euler equations of fluid dynamics are chosen as the mathematical model for the process. The equations are solved via the Runge–Kutta discontinuous Galerkin method and the special DiamondTorre algorithm for multi-GPU implementation is used. (paper)

  16. (Heckel) seeds

    African Journals Online (AJOL)

    UTILISATEUR

    Garcinia kola seeds to six different hormonal pre-germination treatments. This consisted of ... Thus, seed dormancy in this case is not a coat- imposed .... development of the cultivation of the species. The cause .... Hormonal regulation of seed ...

  17. Numerical simulation of the regularized long wave equation by He's homotopy perturbation method

    International Nuclear Information System (INIS)

    Inc, Mustafa; Ugurlu, Yavuz

    2007-01-01

    In this Letter, we present the homotopy perturbation method (shortly HPM) for obtaining the numerical solution of the RLW equation. We obtain the exact and numerical solutions of the Regularized Long Wave (RLW) equation for certain initial condition. The initial approximation can be freely chosen with possible unknown constants which can be determined by imposing the boundary and initial conditions. Comparison of the results with those of other methods have led us to significant consequences. The numerical solutions are compared with the known analytical solutions

  18. In vitro model for human endothelial cell seeding of a small diameter vascular graft

    International Nuclear Information System (INIS)

    Kent, K.C.; Oshima, A.; Ikemoto, T.; Whittemore, A.D.

    1988-01-01

    A precise system was devised to measure the kinetics of attachment of human venous endothelium to a variety of materials and substrates. Cells were labelled in a postconfluent state with tritiated thymidine, harvested, and a cell suspension seeded into a 4 mm PTFE graft. After a 90 minute incubation period, one half of the graft segment was sacrificed and the remaining portion placed in a perfusion system (225 cc/min) for 1 hour. Graft segments, effluents, and seeding suspension were assayed in a beta scintillation counter. The percentage of cells that attached pre- and postperfusion were determined, as well as the retrieval of tritium from the system. Initially, 71% of seeded cells attached to grafts coated with fibronectin, with significantly less (60%) remaining attached after perfusion. Only 10% of cells initially attached to uncoated grafts, with 4% retained postperfusion. Retrieval of tritium averaged 102 +/- 10% for all experiments. This system determines both pre- and postperfusion attachment of human endothelial cells to vascular grafts following manipulation of numerous variables, including graft material, substrate, incubation time, and seeding density. An optimal seeding protocol for human trials can thus be determined

  19. Magnetic perturbations seen by CHAMP and evaluated using the TIE-GCM

    Directory of Open Access Journals (Sweden)

    D. T. Mozzoni

    2007-07-01

    Full Text Available The Thermosphere-Ionosphere Electrodynamics General Circulation Model (TIE-GCM is a self-consistent, global, atmospheric model that can be used to estimate magnetic perturbations at satellite altitude. These computed perturbations can then be compared with the magnetic vector data provided by low-earth orbiting satellites. In this initial study, the quietest day of each month from 2001–2005 was selected for comparison. CHAMP magnetic vector residuals were computed for these intervals using the CHAOS model to remove core and crustal geomagnetic contributions. Under various input parameters, the TIE-GCM predictions were compared with the CHAMP residuals on an orbit by orbit basis. Initial results demonstrate a reasonable agreement between the TIE-GCM estimates and the CHAMP residuals in non-polar, dayside regions (±50° magnetic latitude where both are able to resolve the Equatorial Electro-Jet (EEJ and solar quiet (Sq current systems. Although no clear component or temporal correlation was discerned, evidence showing the decrease in residual comparisons presents the possibility of using the TIE-GCM to pre-process geomagnetic data for main field modeling purposes.

  20. Transition of ion-acoustic perturbations in multicomponent plasma with negative ions

    International Nuclear Information System (INIS)

    Sharma, Sumita Kumari; Devi, Kavita; Adhikary, Nirab Chandra; Bailung, Heremba

    2008-01-01

    Evolution of ion-acoustic compressive (positive) and rarefactive (negative) perturbations in a multicomponent plasma with negative ions has been investigated in a double plasma device. Transition of compressive solitons in electron-positive ion plasma, into a dispersing train of oscillations in a multicomponent plasma, when the negative ion concentration r exceeds a critical value r c , has been observed. On the other hand, an initial rarefactive perturbation initially evolves into a dispersing train of oscillations in electron-positive ion plasma and transforms into rarefactive solitons in a multicomponent plasma when the negative ion concentration is higher than the critical value. The Mach velocity and width of the compressive and rarefactive solitons are measured. The compressive solitons in the range 0 c and the rarefactive solitons in the range r>r c have different characteristics than the Korteweg-de Vries (KdV) solitons at r=0 and modified KdV solitons at r=r c . A nonlinear differential equation having two terms to account for the lower and higher order nonlinearity has been used to explain the observed results

  1. Effects of seed magnetic fields on magnetohydrodynamic implosion structure and dynamics

    KAUST Repository

    Mostert, W.

    2014-12-01

    The effects of various seed magnetic fields on the dynamics of cylindrical and spherical implosions in ideal magnetohydrodynamics are investigated. Here, we present a fundamental investigation of this problem utilizing cylindrical and spherical Riemann problems under three seed field configurations to initialize the implosions. The resulting flows are simulated numerically, revealing rich flow structures, including multiple families of magnetohydrodynamic shocks and rarefactions that interact non-linearly. We fully characterize these flow structures, examine their axi- and spherisymmetry-breaking behaviour, and provide data on asymmetry evolution for different field strengths and driving pressures for each seed field configuration. We find that out of the configurations investigated, a seed field for which the implosion centre is a saddle point in at least one plane exhibits the least degree of asymmetry during implosion.

  2. Phenolics in the seed coat of wild soybean (Glycine soja) and their significance for seed hardness and seed germination.

    Science.gov (United States)

    Zhou, San; Sekizaki, Haruo; Yang, Zhihong; Sawa, Satoko; Pan, Jun

    2010-10-27

    Hardseededness in annual wild soybean (Glycine soja Sieb. Et Zucc.) is a valuable trait that affects the germination, viability, and quality of stored seeds. Two G. soja ecotypes native to Shandong Province of China have been used to identify the phenolics in the seed coat that correlate with the seed hardness and seed germination. Three major phenolics from the seed coat were isolated and identified as epicatechin, cyanidin 3-O-glucoside, and delphinidin 3-O-glucoside. Of the three phenolics, only the change of epicatechin exhibited a significant positive correlation with the change of hard seed percentages both under different water conditions during seed development and under different gas conditions during seed storage. Epicatechin also reveals a hormesis-like effect on the seed germination of G. soja. Epicatechin is suggested to be functionally related to coat-imposed hardseededness in G. soja.

  3. Seed predators exert selection on the subindividual variation of seed size.

    Science.gov (United States)

    Sobral, M; Guitián, J; Guitián, P; Larrinaga, A R

    2014-07-01

    Subindividual variation among repeated organs in plants constitutes an overlooked level of variation in phenotypic selection studies, despite being a major component of phenotypic variation. Animals that interact with plants could be selective agents on subindividual variation. This study examines selective pressures exerted during post-dispersal seed predation and germination on the subindividual variation of seed size in hawthorn (Crataegus monogyna). With a seed offering experiment and a germination test, we estimated phenotypic selection differentials for average and subindividual variation of seed size due to seed predation and germination. Seed size affects germination, growth rate and the probability of an individual seed of escaping predation. Longer seeds showed higher germination rates, but this did not result in significant selection on phenotypes of the maternal trees. On the other hand, seed predators avoided wider seeds, and by doing so exerted phenotypic selection on adult average and subindividual variation of seed size. The detected selection on subindividual variation suggests that the levels of phenotypic variation within individual plants may be, at least partly, the adaptive consequence of animal-mediated selection. © 2013 German Botanical Society and The Royal Botanical Society of the Netherlands.

  4. Optimal Damping of Perturbations of Moving Thermoelastic Panel

    Science.gov (United States)

    Banichuk, N. V.; Ivanova, S. Yu.

    2018-01-01

    The translational motion of a thermoelastic web subject to transverse vibrations caused by initial perturbations is considered. It is assumed that a web moving with a constant translational velocity is described by the model of a thermoelastic panel simply supported at its ends. The problem of optimal damping of vibrations when applying active transverse actions is formulated. For solving the optimization problem, modern methods developed in control theory for systems with distributed parameters described by partial differential equations are used.

  5. Producing the target seed: Seed collection, treatment, and storage

    Science.gov (United States)

    Robert P. Karrfalt

    2011-01-01

    The role of high quality seeds in producing target seedlings is reviewed. Basic seed handling and upgrading techniques are summarized. Current advances in seed science and technology as well as those on the horizon are discussed.

  6. Comparison of secondary organic aerosol formation from toluene on initially wet and dry ammonium sulfate particles at moderate relative humidity

    Directory of Open Access Journals (Sweden)

    T. Liu

    2018-04-01

    Full Text Available The formation of secondary organic aerosol (SOA has been widely studied in the presence of dry seed particles at low relative humidity (RH. At higher RH, initially dry seed particles can exist as wet particles due to water uptake by the seeds as well as the SOA. Here, we investigated the formation of SOA from the photooxidation of toluene using an oxidation flow reactor in the absence of NOx under a range of OH exposures on initially wet or dry ammonium sulfate (AS seed particles at an RH of 68 %. The ratio of the SOA yield on wet AS seeds to that on dry AS seeds, the relative SOA yield, decreased from 1.31 ± 0.02 at an OH exposure of 4.66 × 1010 molecules cm−3 s to 1.01 ± 0.01 at an OH exposure of 5.28 × 1011 molecules cm−3 s. This decrease may be due to the early deliquescence of initially dry AS seeds after being coated by highly oxidized toluene-derived SOA. SOA formation lowered the deliquescence RH of AS and resulted in the uptake of water by both AS and SOA. Hence the initially dry AS seeds contained aerosol liquid water (ALW soon after SOA formed, and the SOA yield and ALW approached those of the initially wet AS seeds as OH exposure and ALW increased, especially at high OH exposure. However, a higher oxidation state of the SOA on initially wet AS seeds than that on dry AS seeds was observed at all levels of OH exposure. The difference in mass fractions of m ∕ z 29, 43 and 44 of SOA mass spectra, obtained using an aerosol mass spectrometer (AMS, indicated that SOA formed on initially wet seeds may be enriched in earlier-generation products containing carbonyl functional groups at low OH exposures and later-generation products containing acidic functional groups at high exposures. Our results suggest that inorganic dry seeds become at least partially deliquesced particles during SOA formation and hence that ALW is inevitably involved in the SOA formation at moderate RH. More laboratory

  7. How a traditional company seeded new analytics capabilities

    NARCIS (Netherlands)

    Gust, G. (Gunther); D. Neumann (Dirk); Flath, C.M. (Christoph M.); T. Brandt (Tobias); Ströhle, P. (Philipp)

    2017-01-01

    textabstractDeveloping state-of-the art data analytics capabilities is a challenge for traditional companies with long-established processes and legacy systems. We describe how one such company (a Swiss electricity utility) conducted a seed project-a bottom-up initiative to develop an analytics

  8. The beginning of a seed: regulatory mechanisms of double fertilization.

    Science.gov (United States)

    Bleckmann, Andrea; Alter, Svenja; Dresselhaus, Thomas

    2014-01-01

    THE LAUNCH OF SEED DEVELOPMENT IN FLOWERING PLANTS (ANGIOSPERMS) IS INITIATED BY THE PROCESS OF DOUBLE FERTILIZATION: two male gametes (sperm cells) fuse with two female gametes (egg and central cell) to form the precursor cells of the two major seed components, the embryo and endosperm, respectively. The immobile sperm cells are delivered by the pollen tube toward the ovule harboring the female gametophyte by species-specific pollen tube guidance and attraction mechanisms. After pollen tube burst inside the female gametophyte, the two sperm cells fuse with the egg and central cell initiating seed development. The fertilized central cell forms the endosperm while the fertilized egg cell, the zygote, will form the actual embryo and suspensor. The latter structure connects the embryo with the sporophytic maternal tissues of the developing seed. The underlying mechanisms of double fertilization are tightly regulated to ensure delivery of functional sperm cells and the formation of both, a functional zygote and endosperm. In this review we will discuss the current state of knowledge about the processes of directed pollen tube growth and its communication with the synergid cells resulting in pollen tube burst, the interaction of the four gametes leading to cell fusion and finally discuss mechanisms how flowering plants prevent multiple sperm cell entry (polyspermy) to maximize their reproductive success.

  9. Hot seeding using large Y-123 seeds

    International Nuclear Information System (INIS)

    Scruggs, S J; Putman, P T; Zhou, Y X; Fang, H; Salama, K

    2006-01-01

    There are several motivations for increasing the diameter of melt textured single domain discs. The maximum magnetic field produced by a trapped field magnet is proportional to the radius of the sample. Furthermore, the availability of trapped field magnets with large diameter could enable their use in applications that have traditionally been considered to require wound electromagnets, such as beam bending magnets for particle accelerators and electric propulsion. We have investigated the possibility of using large area epitaxial growth instead of the conventional point nucleation growth mechanism. This process involves the use of large Y123 seeds for the purpose of increasing the maximum achievable Y123 single domain size. The hot seeding technique using large Y-123 seeds was employed to seed Y-123 samples. Trapped field measurements indicate that single domain samples were indeed grown by this technique. Microstructural evaluation indicates that growth can be characterized by a rapid nucleation followed by the usual peritectic grain growth which occurs when large seeds are used. Critical temperature measurements show that no local T c suppression occurs in the vicinity of the seed. This work supports the suggestion of using an iterative method for increasing the size of Y-123 single domains that can be grown

  10. Frugivores and seed dispersal: mechanisms and consequences for biodiversity of a key ecological interaction

    OpenAIRE

    Jordano, Pedro; Forget, Pierre-Michel; Lambert, Joanna E.; Böhning-Gaese, Katrin; Traveset, Anna; Wright, S. Joseph

    2010-01-01

    The 5th Symposium on Frugivores and Seed Dis- persal, held in Montpellier (France), 13 – 18 June 2010, brought together more than 220 researchers exemplifying a wide diversity of approaches to the study of frugivory and dispersal of seeds. Fol- lowing Ted Fleming and Alejandro Estrada’s initiative in 1985, this event was a celebration of the 25th anniversary of the first meeting in Veracruz, Mexico. Frugivory and seed dispersal are active research areas that hav...

  11. Report on seed born diseases in organic seed and propagation material

    OpenAIRE

    Micheloni, C.; Plakolm, G.; Schärer, H.

    2007-01-01

    The key questions which will be addressed in this report are: • Are seed born diseases an important factor that prevents seed companies from producing organic seeds and organic farmers from using them? • Which seed treatments are available in organic farming? Which treatments are or will be acceptable? To which degree are they effective? • Are the thresholds for seed born diseases different among Member States? Can this cause unfair competition among farmers and seed producers? • ...

  12. Seed drill depth control system for precision seeding

    DEFF Research Database (Denmark)

    Kirkegaard Nielsen, Søren; Munkholm, Lars Juhl; Lamandé, Mathieu

    2018-01-01

    acting on the drill coulters, which generates unwanted vibrations and, consequently, a non-uniform seed placement. Therefore, a proof-of-concept dynamic coulter depth control system for a low-cost seed drill was developed and studied in a field experiment. The performance of the active control system...... depth control system this variability was reduced to±2 mm. The system with the active control system operated more accurately at an operational speed of 12 km h−1 than at 4 km h−1 without the activated control system.......An adequate and uniform seeding depth is crucial for the homogeneous development of a crop, as it affects time of emergence and germination rate. The considerable depth variations observed during seeding operations - even for modern seed drills - are mainly caused by variability in soil resistance...

  13. Auxin production in the endosperm drives seed coat development in Arabidopsis

    Science.gov (United States)

    Figueiredo, Duarte D; Batista, Rita A; Roszak, Pawel J; Hennig, Lars; Köhler, Claudia

    2016-01-01

    In flowering plants, seed development is initiated by the fusion of the maternal egg and central cells with two paternal sperm cells, leading to the formation of embryo and endosperm, respectively. The fertilization products are surrounded by the maternally derived seed coat, whose development prior to fertilization is blocked by epigenetic regulators belonging to the Polycomb Group (PcG) protein family. Here we show that fertilization of the central cell results in the production of auxin and most likely its export to the maternal tissues, which drives seed coat development by removing PcG function. We furthermore show that mutants for the MADS-box transcription factor AGL62 have an impaired transport of auxin from the endosperm to the integuments, which results in seed abortion. We propose that AGL62 regulates auxin transport from the endosperm to the integuments, leading to the removal of the PcG block on seed coat development. DOI: http://dx.doi.org/10.7554/eLife.20542.001 PMID:27848912

  14. Quantum system lifetimes and measurement perturbations

    International Nuclear Information System (INIS)

    Najakov, E.

    1977-05-01

    The recently proposed description of quantum system decay in terms of repeated measurement perturbations is modified. The possibility of retarded reductions to a unique quantum state, due to ineffective localization of the decay products at initial time measurements, is simply taken into account. The exponential decay law is verified again. A modified equation giving the observed lifetime in terms of unperturbed quantum decay law, measurement frequency and reduction law is derived. It predicts deviations of the observed lifetime from the umperturbed one, together with a dependence on experimental procedures. The influence of different model unperturbed decay laws and reduction laws on this effect is studied

  15. Effects of seed fermentation method on seed germination and vigor ...

    African Journals Online (AJOL)

    The present study was conducted to examine the influence of Lagenaria siceraria seed fermentation method on seed germination and vigor. Three seed fermentation methods (fermented in ambient air, plastic bag stored in ambient or in plastic bag buried) were tested on two cultivars during two years. Seed germination and ...

  16. Seed selection by earthworms : chemical seed properties matter more than morphological traits

    OpenAIRE

    Clause, J.; Forey, E.; Eisenhauer, N.; Seal, C.E.; Soudey, A.; Colville, L.; Barot, Sébastien

    2017-01-01

    Aims : The passage of seeds through the earthworm gut potentially damages seeds, altering seed and seedling performances depending on seed traits. This work was conducted to study to what extent chemical and morphological seed traits determine the seed attractiveness for earthworms. Methods : We tested seed selection via the ingestion and digestion of 23 grassland plant species spanning a range of 14 morphological and chemical traits by two common earthworm species: the anecic Lumbricus te...

  17. Studies on the Vigour of Soybean Seeds : II. Varietal Differences in Seed Coat Quality and Swelling Components of Seed during Moisture Imbibition

    OpenAIRE

    Mugnisjah, Wahju Qamara; Shimano, Itaru; Matsumoto, Shigeo; 島野, 至; 松本, 重男

    1987-01-01

    Laboratory experiment was conducted to elucidate the physiological factor determining the association of seed size and seed coat quality with varietal differences in seed vigour, and to pursue an alternative on the mechanism of varietal differences in seed resistance to field weathering. Results of this study revealed that seed polymer change (seed volume change minus seed weight change during moisture imbibition) was the physiological factor determining the association of seed size and seed ...

  18. 19 CFR 10.57 - Certified seed potatoes, and seed corn or maize.

    Science.gov (United States)

    2010-04-01

    ... 19 Customs Duties 1 2010-04-01 2010-04-01 false Certified seed potatoes, and seed corn or maize... Provisions Potatoes, Corn, Or Maize § 10.57 Certified seed potatoes, and seed corn or maize. Claim for classification as seed potatoes under subheading 0701.10.00, as seed corn (maize) under subheading 1005.10...

  19. Initial-state interactions, factorization, and the Drell-Yan process

    International Nuclear Information System (INIS)

    Bodwin, G.T.; Brodsky, S.J.; Lepage, G.P.

    1981-12-01

    It is shown that initial state interactions violate the factorization conjecture for the Drell-Yan process order by order in perturbation theory. Also, the effects of elastic and inelastic initial state interactions on the observed cross sections are discussed

  20. Singular perturbation of simple eigenvalues

    International Nuclear Information System (INIS)

    Greenlee, W.M.

    1976-01-01

    Two operator theoretic theorems which generalize those of asymptotic regular perturbation theory and which apply to singular perturbation problems are proved. Application of these theorems to concrete problems is involved, but the perturbation expansions for eigenvalues and eigenvectors are developed in terms of solutions of linear operator equations. The method of correctors, as well as traditional boundary layer techniques, can be used to apply these theorems. The current formulation should be applicable to highly singular ''hard core'' potential perturbations of the radial equation of quantum mechanics. The theorems are applied to a comparatively simple model problem whose analysis is basic to that of the quantum mechanical problem

  1. Scalar cosmological perturbations

    International Nuclear Information System (INIS)

    Uggla, Claes; Wainwright, John

    2012-01-01

    Scalar perturbations of Friedmann-Lemaitre cosmologies can be analyzed in a variety of ways using Einstein's field equations, the Ricci and Bianchi identities, or the conservation equations for the stress-energy tensor, and possibly introducing a timelike reference congruence. The common ground is the use of gauge invariants derived from the metric tensor, the stress-energy tensor, or from vectors associated with a reference congruence, as basic variables. Although there is a complication in that there is no unique choice of gauge invariants, we will show that this can be used to advantage. With this in mind our first goal is to present an efficient way of constructing dimensionless gauge invariants associated with the tensors that are involved, and of determining their inter-relationships. Our second goal is to give a unified treatment of the various ways of writing the governing equations in dimensionless form using gauge-invariant variables, showing how simplicity can be achieved by a suitable choice of variables and normalization factors. Our third goal is to elucidate the connection between the metric-based approach and the so-called 1 + 3 gauge-invariant approach to cosmological perturbations. We restrict our considerations to linear perturbations, but our intent is to set the stage for the extension to second-order perturbations. (paper)

  2. Divergent Perturbation Series

    International Nuclear Information System (INIS)

    Suslov, I.M.

    2005-01-01

    Various perturbation series are factorially divergent. The behavior of their high-order terms can be determined by Lipatov's method, which involves the use of instanton configurations of appropriate functional integrals. When the Lipatov asymptotic form is known and several lowest order terms of the perturbation series are found by direct calculation of diagrams, one can gain insight into the behavior of the remaining terms of the series, which can be resummed to solve various strong-coupling problems in a certain approximation. This approach is demonstrated by determining the Gell-Mann-Low functions in φ 4 theory, QED, and QCD with arbitrary coupling constants. An overview of the mathematical theory of divergent series is presented, and interpretation of perturbation series is discussed. Explicit derivations of the Lipatov asymptotic form are presented for some basic problems in theoretical physics. A solution is proposed to the problem of renormalon contributions, which hampered progress in this field in the late 1970s. Practical perturbation-series summation schemes are described both for a coupling constant of order unity and in the strong-coupling limit. An interpretation of the Borel integral is given for 'non-Borel-summable' series. Higher order corrections to the Lipatov asymptotic form are discussed

  3. Influence of postradiation moisture alteration on biological after-effect in Crepis seeds

    Energy Technology Data Exchange (ETDEWEB)

    Atayan, R R; Gabrielian, J Y [AN Armyanskoj SSR, Erevan. Inst. Fiziki

    1978-02-01

    A series of X-ray exposures was given to Crepis capillaris seeds of different water contents. Cytogenetic changes in the seeds were determined immediately after irradiation and after storage at different relative humidities. The amount of damage that developed during postirradiation storage as well as the initial radiobiological effect decreased as seed water content increased from 2.4% to 7.6 to 12.6%. Differences in postirradiation damage were revealed within four hours of storage and manifest as a fast component to the curve of storage versus damage. In seeds of 7.6 and 12.6% water content, both the amount of biological after-effect and the rate of injury progression did not depend markedly on relative humidity of storage atmosphere. These seeds demonstrated only a slow after-effect, which appeared to be the same at any seed-moisture level, thus indicating that only the fast component is subject to postirradiation modification. With dry irradiated seeds demonstrating fast postirradiation injury progression, the following results were obtained: (a) after-effect in seeds of 2.4% water content decreased with increasing humidity of storage atmosphere; no after-effect developed when the seeds were stored at 100% relative humidity; (b) after-effect in seeds of 6% water content was significantly increased if they were stored at 0% relative humidity. These results are consistent with the pattern expected of a free radical concept.

  4. Seed ecology and regeneration in dry Afromontane forests of Ethiopia

    Energy Technology Data Exchange (ETDEWEB)

    Teketay, D. [Swedish Univ. of Agricultural Sciences, Umeaa (Sweden). Dept. of Forest Vegetation Ecology

    1996-12-31

    Various aspects of seed and regeneration ecology: germination requirements of seeds, seed longevity in the soil, soil seed banks in forests, gaps and arable land as well as density, survival and growth of seedlings were investigated within the dry Afromontane region in Ethiopia. In laboratory germination tests, 60% of the species studied exhibited some degree of initial dormancy and the optimum constant temperature for germination was between 20 and 25 deg C in the majority of the species. A few species showed a requirement for fluctuating temperatures and germination was suppressed or completely inhibited in several, mainly small-seeded, species when they were incubated in darkness or in light filtered through green leaves. Hard-seeded species required scarification treatments to improve germination, indicating seed-coat imposed dormancy. Dry storage reduced the germinability of seeds in a few species, suggesting a recalcitrant behaviour, while seeds of many species remained unaffected. During four years of storage in forest soils, seeds of 2 out of 8 species germinated in the soil almost completely within a year, 2 of the species maintained nearly full viability, while 4 were intermediate. The generally high levels of dormancy and somewhat extended viability of seeds in the soil may have been selected for under a climate of seasonal drought and unreliable rainfall that characterizes the dry Afromontane region. Dry Afromontane forests have a potential to recover in relatively short time after natural and man-made disturbances, e.g. after carefully managed selective cutting. However, the common practice of clearing forests and converting them into permanent arable land destroys the sources of regrowth thereby preventing regeneration of the forest vegetation. Therefore, the fate of dry Afromontane forests depends on the protection, careful management and conservation of the remaining patches. 102 refs, 4 figs, 1 tab

  5. Yield and quality of white mustard seed depending on the seeding dates

    Directory of Open Access Journals (Sweden)

    Jevđović Radosav

    2000-01-01

    Full Text Available The effect of sowing dates and harvest dates on yield and quality of white mustard seed been investigated in this study. During the experiment two sowing dates have been tested the first one based on the crops in March, and the other one when the direct sowing was carried out in late May, after the harvest of camomile crops. The harvest of the seed crops in the first seeding date was performed on 1st July, and the second on 15th September. Seed fractioning extracted the following fractions: large (3mm, medium (2 mm and small (1mm. I he objective of the laboratory' experiments was to observe the effect of the seed fraction size on the most important parameters of its quality (germination energy, total germination and absolute mass according to the stipulated terms. Based on the data obtained in the survey, it can be concluded that the seed yield is significantly affected by the varied seeding dates. Earlier seeding date produced significantly increased seed yield (1920 kg/ha than the later seeding date (1160 kg/ha. According to the seed quality parameters, the best characteristics are found in the seed fraction of 3 mm, in both seeding and harvest dates.

  6. Large-order perturbation theory

    International Nuclear Information System (INIS)

    Wu, T.T.

    1982-01-01

    The original motivation for studying the asymptotic behavior of the coefficients of perturbation series came from quantum field theory. An overview is given of some of the attempts to understand quantum field theory beyond finite-order perturbation series. At least is the case of the Thirring model and probably in general, the full content of a relativistic quantum field theory cannot be recovered from its perturbation series. This difficulty, however, does not occur in quantum mechanics, and the anharmonic oscillator is used to illustrate the methods used in large-order perturbation theory. Two completely different methods are discussed, the first one using the WKB approximation, and a second one involving the statistical analysis of Feynman diagrams. The first one is well developed and gives detailed information about the desired asymptotic behavior, while the second one is still in its infancy and gives instead information about the distribution of vertices of the Feynman diagrams

  7. Effects of rodent species, seed species, and predator cues on seed fate

    Science.gov (United States)

    Sivy, Kelly J.; Ostoja, Steven M.; Schupp, Eugene W.; Durham, Susan

    2011-07-01

    Seed selection, removal and subsequent management by granivorous animals is thought to be a complex interaction of factors including qualities of the seeds themselves (e.g., seed size, nutritional quality) and features of the local habitat (e.g. perceived predator risk). At the same time, differential seed selection and dispersal is thought to have profound effects on seed fate and potentially vegetation dynamics. In a feeding arena, we tested whether rodent species, seed species, and indirect and direct predation cues influence seed selection and handling behaviors (e.g., scatter hoarding versus larder hoarding) of two heteromyid rodents, Ord's kangaroo rat ( Dipodomys ordii) and the Great Basin pocket mouse ( Perognathus parvus). The indirect cue was shrub cover, a feature of the environment. Direct cues, presented individually, were (1) control, (2) coyote ( Canis latrans) vocalization, (3) coyote scent, (4) red fox ( Vulpes vulpes) scent, or (5) short-eared owl ( Asio flammeus) vocalization. We offered seeds of three sizes: two native grasses, Indian ricegrass ( Achnatherum hymenoides) and bluebunch wheatgrass ( Pseudoroegneria spicata), and the non-native cereal rye ( Secale cereale), each in separate trays. Kangaroo rats preferentially harvested Indian ricegrass while pocket mice predominately harvested Indian ricegrass and cereal rye. Pocket mice were more likely to scatter hoard preferred seeds, whereas kangaroo rats mostly consumed and/or larder hoarded preferred seeds. No predator cue significantly affected seed preferences. However, both species altered seed handling behavior in response to direct predation cues by leaving more seeds available in the seed pool, though they responded to different predator cues. If these results translate to natural dynamics on the landscape, the two rodents are expected to have different impacts on seed survival and plant recruitment via their different seed selection and seed handling behaviors.

  8. Evidence for Gravity Wave Seeding of Convective Ionosphere Storms Initiated by Deep Troposphere Convection

    Science.gov (United States)

    Kelley, M. C.; Pfaff, R. F., Jr.; Dao, E. V.; Holzworth, R. H., II

    2014-12-01

    With the increase in solar activity, the Communications/Outage Forecast System satellite (C/NOFS) now goes below the F peak. As such, we now can study the development of Convective Ionospheric Storms (CIS) and, most importantly, large-scale seeding of the low growth-rate Rayleigh-Taylor (R-T) instability. Two mechanisms have been suggested for such seeding: the Collisional Kelvin-Helmholtz Instability (CKHI) and internal atmospheric gravity waves. A number of observations have shown that the spectrum of fully developed topside structures peaks at 600 km and extends to over 1000 km. These structures are exceedingly difficult to explain by CKHI. Here we show that sinusoidal plasma oscillations on the bottomside during daytime develop classical R-T structures on the nightside with the background 600 km structure still apparent. In two case studies, thunderstorm activity was observed east of the sinusoidal features in the two hours preceding the C/NOFS passes. Thus, we argue that convective tropospheric storms are a likely source of these sinusoidal features.

  9. Establishment of post-harvest early-developmental categories for viability maintenance of Araucaria angustifolia seeds

    Directory of Open Access Journals (Sweden)

    Cristhyane Garcia Araldi

    2015-12-01

    Full Text Available Araucaria angustifolia seeds are recalcitrant, and their metabolism remains high during storage. This research aimed to describe the initiation of germination in A. angustifolia seeds during storage in order to standardize the assessment of physiological quality and to promote seed conservation. Seeds were collected from two populations and stored for 270 days in the natural laboratory environment and cold chamber. Seeds were classified according to four early developmental stages: I - mature seeds; II - seeds with elongation along the embryonic axis; III - beginning of root protrusion; IV - advanced germination stage, with seedling shoots. After categorization, physical and physiological quality was assessed. In freshly collected seeds, only category I was observed. At 270 days, approximately 40% of seeds were in category III in laboratory conditions, while the maintenance in a cold chamber delayed germinative metabolism. Viability tests showed that seeds in categories III and IV were more susceptible to damage caused by storage. In conclusion, the percentage of viable A. angustifolia seeds depends on the development stage after collection. Seeds that have reached early developmental category III should be prioritized for propagation, while those remaining in categories I and II should be longer stored with periodic assessment for reduction in physiological quality.

  10. Perturbation theory in light-cone gauge

    International Nuclear Information System (INIS)

    Vianello, Eliana

    2000-01-01

    Perturbation calculations are presented for the light-cone gauge Schwinger model. Eigenstates can be calculated perturbatively but the perturbation theory is nonstandard. We hope to extend the work to QCD 2 to resolve some outstanding issues in those theories

  11. Alleviate Seed Ageing Effects in Silybum marianum by Application of Hormone Seed Priming

    Directory of Open Access Journals (Sweden)

    Seyed Ata SIADAT

    2015-09-01

    Full Text Available Most of the medicinal plants have seed dormancy or poor seed germination. This is due to their natural compounds or their morphological structure. Existence of such mechanisms makes the seeds able to endure harsh environments, stressful conditions or natural ageing. Different seed enhancement treatments were proposed in order to improve seed germination. In this study, it was examined Silybum marianum seed longevity (0, 48 and 72 hour of ageing and the response to seed priming when using different concentrations of cytokinin (50, 200, 350 and 500 ppm and different duration of treatment (8, 12 and 24 hour. Results revealed that ageing could be successfully alleviated using seed priming. Seed ageing significantly affected seed germination and vigour. Application of cytokinin considerably improved seed vigour in aged and non aged seeds. The most effective seed priming treatment was with 500 ppm cytokine, with the duration of 24 hours. In conclusion, it can be recommend the used of plant growth regulators like cytokine, as a good priming agent, to recover losses of seed quality and improve germination characteristics.

  12. Selected aspects of tiny vetch [Vicia hirsuta (L. Gray S.F.] seed ecology: generative reproduction and effects of seed maturity and seed storage on seed germination

    Directory of Open Access Journals (Sweden)

    Magdalena Kucewicz

    2012-12-01

    Full Text Available Vicia hirsuta (L. Gray S.F. (tiny vetch is a common and persistent segetal weed. Tiny vetch seeds and pods reach different stages of maturity during the crop harvest season. Some seeds that mature before cereal harvest are shed in the field and deposited in the soil seed bank, while others become incorporated into seed material. The objective of this study was to describe selected aspects of tiny vetch seed ecology: to determine the rate of individual reproduction of vetch plants growing in winter and spring grain crops and to evaluate the germination of seeds at different stages of maturity, subject to storage conditions. The seeds and pods of V. hirsuta were sorted according to their development stages at harvest and divided into two groups. The first group was stored under laboratory conditions for two months. In the autumn of the same year, the seeds were subjected to germination tests. The remaining seeds were stored in a storeroom, and were planted in soil in the spring. The germination rate was evaluated after 8 months of storage. Potential productivity (developed pods and flowers, fruit buds was higher in plants fruiting in winter wheat than in spring barley. Vetch plants produced around 17-26% more pods (including cracked, mature, greenish-brown and green pods and around 25% less buds in winter wheat than in spring barley. Immature seeds were characterized by the highest germination capacity. Following storage under laboratory conditions and stratification in soil, mature seeds germinated at a rate of several percent. After storage in a storeroom, seeds at all three development stages broke dormancy at a rate of 72- 75%. The high germination power of tiny vetch seeds stored in a storeroom indicates that this plant can be classified as an obligatory speirochoric weed species.

  13. Non-gaussianity versus nonlinearity of cosmological perturbations.

    Science.gov (United States)

    Verde, L

    2001-06-01

    Following the discovery of the cosmic microwave background, the hot big-bang model has become the standard cosmological model. In this theory, small primordial fluctuations are subsequently amplified by gravity to form the large-scale structure seen today. Different theories for unified models of particle physics, lead to different predictions for the statistical properties of the primordial fluctuations, that can be divided in two classes: gaussian and non-gaussian. Convincing evidence against or for gaussian initial conditions would rule out many scenarios and point us toward a physical theory for the origin of structures. The statistical distribution of cosmological perturbations, as we observe them, can deviate from the gaussian distribution in several different ways. Even if perturbations start off gaussian, nonlinear gravitational evolution can introduce non-gaussian features. Additionally, our knowledge of the Universe comes principally from the study of luminous material such as galaxies, but galaxies might not be faithful tracers of the underlying mass distribution. The relationship between fluctuations in the mass and in the galaxies distribution (bias), is often assumed to be local, but could well be nonlinear. Moreover, galaxy catalogues use the redshift as third spatial coordinate: the resulting redshift-space map of the galaxy distribution is nonlinearly distorted by peculiar velocities. Nonlinear gravitational evolution, biasing, and redshift-space distortion introduce non-gaussianity, even in an initially gaussian fluctuation field. I investigate the statistical tools that allow us, in principle, to disentangle the above different effects, and the observational datasets we require to do so in practice.

  14. Investigation of the operating conditions to morphology evolution of β-L-glutamic acid during seeded cooling crystallization

    Science.gov (United States)

    Zhang, Fangkun; Liu, Tao; Huo, Yan; Guan, Runduo; Wang, Xue Z.

    2017-07-01

    In this paper the effects of operating conditions including cooling rate, initial supersaturation, and seeding temperature were investigated on the morphology evolution of β-L-glutamic acid (β-LGA) during seeded cooling crystallization. Based on the results of in-situ image acquisition of the crystal morphology evolution during the crystallization process, it was found that the crystal products tend to be plate-like or short rod-like under a slow cooling rate, low initial supersaturation, and low seeding temperature. In the opposite, the operating conditions of a faster cooling rate, higher initial supersaturation, and higher seeding temperature tend to produce long rod-like or needle-like crystals, and meanwhile, the length and width of crystal products will be increased together with a wider crystal size distribution (CSD). The aspect ratio of crystals, defined by the crystal length over width measured from in-situ or sample images, was taken as a shape index to analyze the crystal morphologies. Based on comparative analysis of the experimental results, guidelines on these operating conditions were given for obtaining the desired crystal shapes, along with the strategies for obtaining a narrower CSD for better product quality. Experimental verifications were performed to illustrate the proposed guidelines on the operating conditions for seeded cooling crystallization of LGA solution.

  15. Preventing thermoinhibition in a thermosensitive lettuce genotype by seed imbibition at low temperature

    Directory of Open Access Journals (Sweden)

    Nascimento Warley Marcos

    2003-01-01

    Full Text Available Lettuce (Lactuca sativa L. seed germination is strongly temperature dependent and under high temperatures, germination of most of genotypes can be erratic or completely inhibited. Lettuce seeds of 'Dark Green Boston' (DGB were incubated at temperatures ranging from 15degrees to 35degreesC at light and dark conditions. Other seeds were imbibed in dark at 20degrees; 25degrees; 30degrees; and 35degreesC for 8 and 16 hours and then transferred to 20 or 35degreesC, in dark. Seeds were also incubated at constant temperature of 20degrees and 35 degreesC, in the dark, as control. In another treatment, seeds were primed for 3 days at 15degreesC with constant light. DGB lettuce seeds required light to germinate adequately at temperatures above 25degreesC. Seeds incubated at 20degreesC had 97% germination, whereas seeds incubated at 35degreesC did not germinate. Seeds imbibed at 20degreesC for 8 and 16 hours had germination. At 35degreesC, seeds imbibed initially at 20degreesC for 8 and 16 hours, had 89 and 97% germination, respectively. Seeds imbibed at 25degreesC for 16 hours, germinated satisfactory at 35degreesC. High temperatures of imbibition led to no germination. Primed and non-primed seeds had 100% germination at 20degreesC. Primed seeds had 100% germination at 35degreesC, whereas non-primed seeds germinate only 4%. The first hours of imbibition are very critical for lettuce seed germination at high temperatures.

  16. Perturbation Theory of Embedded Eigenvalues

    DEFF Research Database (Denmark)

    Engelmann, Matthias

    project gives a general and systematic approach to analytic perturbation theory of embedded eigenvalues. The spectral deformation technique originally developed in the theory of dilation analytic potentials in the context of Schrödinger operators is systematized by the use of Mourre theory. The group...... of dilations is thereby replaced by the unitary group generated y the conjugate operator. This then allows to treat the perturbation problem with the usual Kato theory.......We study problems connected to perturbation theory of embedded eigenvalues in two different setups. The first part deals with second order perturbation theory of mass shells in massive translation invariant Nelson type models. To this end an expansion of the eigenvalues w.r.t. fiber parameter up...

  17. High voltage electric field effects on structure and biological characteristics of barley seeds

    Energy Technology Data Exchange (ETDEWEB)

    Khazaei, J. [Tehran Univ., Tehran (Iran, Islamic Republic of). Dept. of Agrotechnology, Univ. College of Abouraihan; Aliabadi, E. [Tehran Univ., Tehran (Iran, Islamic Republic of). Dept. of Crop Production Horticulture, Univ. College of Aburaihan; Shayegani, A.A. [Tehran Univ., Tehran (Iran, Islamic Republic of). Univ. College of Engineering

    2010-07-01

    Electric biostimulation of seeds is a pre-sowing treatment in which an electric field is applied to seeds to increase germination of non standard seeds. This paper reported on a study that examined the effects of AC electric field and exposure time on the structure and biological characteristics of barley seeds. The objective was to determine the potential to accelerate seed germination, plant growth and root development by the electric field strength and exposure time. Makooei cultivar barley seeds were used in this study. The effect of electric field strength (at 2, 4, 9, and 14 kV/m) and exposure time (at 15, 45, 80, and 150 min) on seed germination was studied along with height of seedling, length or root, height of stem, length of leaves, earliness, dry weight and wet weight of seedling. The treated seeds were stored for a month in a refrigerator at 5 degrees C prior to the germination experiments. The initial germination percent of the seed was 81 per cent. The treatment of barley seeds in an AC electric field had a positive effect on all investigated parameters. The germination percent of the treated seed increased to 94.5 per cent . The seeds exposed for long periods of time (45 to 150 min) showed better germination than the seeds exposed to lower exposure times. Dry and wet weights of seedling increased 143.4 per cent and 45.7 per cent, respectively.

  18. Clomazone selectivity in cotton seeds treated with dietholate and zinc acetate

    Directory of Open Access Journals (Sweden)

    Miriam Hiroko Inoue

    2014-12-01

    Full Text Available The objective of this study objective was to evaluate the selectivity of pre-emergence applications the herbicide clomazone cotton seeds treated with dietholate and zinc acetate. The 4 x 2 factorial arrangement was adopted (4 seed treatment methods and 2 clomazone dosages, distributed in a randomized block design with 4 repetitions. In treatments where dietholate and zinc acetate were applied, rates of 0.4 kg ha-1 and 8 ml per kg of seeds were used respectively. The clomazone rates used refer to 0.8 and 1.0 kg ha- 1. The cotton cultivar used was the Fiber Max 966 LL. Independent of treatment, all seeds were treated with tiametoxam insecticide and fludioxonil + metalaxyl-M fungicide at rates of 2.24 and 0.08 + 0.03 g per kg of seed, respectively, to control pests early and limit losses caused by pathogens in germination and seedling emergence. Dietholate and zinc acetate treatment had greater initial effect on cotton plants at 21, 30 and 45 days after application. In phytointoxication symptoms were observed for treatment with dietholate and zinc acetate during the evaluation periods. Seeds treated with dietholate, dietholate and zinc acetate or zinc acetate alone provided a higher number of bolls and seed cotton production compared to the control.

  19. Chiral perturbation theory

    International Nuclear Information System (INIS)

    Ecker, G.

    1996-06-01

    After a general introduction to the structure of effective field theories, the main ingredients of chiral perturbation theory are reviewed. Applications include the light quark mass ratios and pion-pion scattering to two-loop accuracy. In the pion-nucleon system, the linear σ model is contrasted with chiral perturbation theory. The heavy-nucleon expansion is used to construct the effective pion-nucleon Lagrangian to third order in the low-energy expansion, with applications to nucleon Compton scattering. (author)

  20. The Matter Bispectrum in N-body Simulations with non-Gaussian Initial Conditions

    OpenAIRE

    Sefusatti, Emiliano; Crocce, Martin; Desjacques, Vincent

    2010-01-01

    We present measurements of the dark matter bispectrum in N-body simulations with non-Gaussian initial conditions of the local kind for a large variety of triangular configurations and compare them with predictions from Eulerian perturbation theory up to one-loop corrections. We find that the effects of primordial non-Gaussianity at large scales, when compared to perturbation theory, are well described by the initial component of the matter bispectrum, linearly extrapolated at the redshift of ...

  1. Transcriptome analysis of Sacha Inchi (Plukenetia volubilis L. seeds at two developmental stages

    Directory of Open Access Journals (Sweden)

    Wang Xiaojuan

    2012-12-01

    Full Text Available Abstract Background Sacha Inchi (Plukenetia volubilis L., Euphorbiaceae is a potential oilseed crop because the seeds of this plant are rich in unsaturated fatty acids (FAs. In particular, the fatty acid composition of its seed oil differs markedly in containing large quantities of α-linolenic acid (18C:3, a kind of ω-3 FAs. However, little is known about the molecular mechanisms responsible for biosynthesis of unsaturated fatty acids in the developing seeds of this species. Transcriptome data are needed to better understand these mechanisms. Results In this study, de novo transcriptome assembly and gene expression analysis were performed using Illumina sequencing technology. A total of 52.6 million 90-bp paired-end reads were generated from two libraries constructed at the initial stage and fast oil accumulation stage of seed development. These reads were assembled into 70,392 unigenes; 22,179 unigenes showed a 2-fold or greater expression difference between the two libraries. Using this data we identified unigenes that may be involved in de novo FA and triacylglycerol biosynthesis. In particular, a number of unigenes encoding desaturase for formation of unsaturated fatty acids with high expression levels in the fast oil accumulation stage compared with the initial stage of seed development were identified. Conclusions This study provides the first comprehensive dataset characterizing Sacha Inchi gene expression at the transcriptional level. These data provide the foundation for further studies on molecular mechanisms underlying oil accumulation and PUFA biosynthesis in Sacha Inchi seeds. Our analyses facilitate understanding of the molecular mechanisms responsible for the high unsaturated fatty acids (especially α-linolenic acid accumulation in Sacha Inchi seeds.

  2. Dynamics of a single ion in a perturbed Penning trap: Octupolar perturbation

    International Nuclear Information System (INIS)

    Lara, Martin; Salas, J. Pablo

    2004-01-01

    Imperfections in the design or implementation of Penning traps may give rise to electrostatic perturbations that introduce nonlinearities in the dynamics. In this paper we investigate, from the point of view of classical mechanics, the dynamics of a single ion trapped in a Penning trap perturbed by an octupolar perturbation. Because of the axial symmetry of the problem, the system has two degrees of freedom. Hence, this model is ideal to be managed by numerical techniques like continuation of families of periodic orbits and Poincare surfaces of section. We find that, through the variation of the two parameters controlling the dynamics, several periodic orbits emanate from two fundamental periodic orbits. This process produces important changes (bifurcations) in the phase space structure leading to chaotic behavior

  3. Binary black hole initial data from matched asymptotic expansions

    International Nuclear Information System (INIS)

    Yunes, Nicolas; Owen, Benjamin J.; Tichy, Wolfgang; Bruegmann, Bernd

    2006-01-01

    We present an approximate metric for a binary black-hole spacetime to construct initial data for numerical relativity. This metric is obtained by asymptotically matching a post-Newtonian metric for a binary system to a perturbed Schwarzschild metric for each hole. In the inner zone near each hole, the metric is given by the Schwarzschild solution plus a quadrupolar perturbation corresponding to an external tidal gravitational field. In the near zone, well outside each black hole but less than a reduced wavelength from the center of mass of the binary, the metric is given by a post-Newtonian expansion including the lowest-order deviations from flat spacetime. When the near zone overlaps each inner zone in a buffer zone, the post-Newtonian and perturbed Schwarzschild metrics can be asymptotically matched to each other. By demanding matching (over a 4-volume in the buffer zone) rather than patching (choosing a particular 2-surface in the buffer zone), we guarantee that the errors are small in all zones. The resulting piecewise metric is made formally C ∞ with smooth transition functions so as to obtain the finite extrinsic curvature of a 3-slice. In addition to the metric and extrinsic curvature, we present explicit results for the lapse and the shift, which can be used as initial data for numerical simulations. This initial data is not accurate all the way to the asymptotically flat ends inside each hole, and therefore must be used with evolution codes which employ black hole excision rather than puncture methods. This paper lays the foundations of a method that can be straightforwardly iterated to obtain initial data to higher perturbative order

  4. Status of perturbative QCD

    International Nuclear Information System (INIS)

    Collins, J.C.

    1985-01-01

    Progress in quantum chromodynamics in the past year is reviewed in these specific areas: proof of factorization for hadron-hadron collisions, fast calculation of higher order graphs, perturbative Monte Carlo calculations for hadron-hadron scattering, applicability of perturbative methods to heavy quark production, and understanding of the small-x problem. 22 refs

  5. Analysis of seed quality in NS sunflower hybrid seed processed between 2010 and 2014

    Directory of Open Access Journals (Sweden)

    Jokić Goran

    2015-01-01

    Full Text Available This paper analyzed the processed seed of five sunflower hybrid seed developed at the Institute of Field and Vegetable Crops in Novi Sad. The cultivars were Rimi PR, Duško, NS Dukat, Sumo 1 PR and Sremac. The analysis was conducted on seed lots processed between 2010 and 2014 and involved the following parameters: seed purity percentage, 1000-seed weight, germination energy, germination, seed moisture, number of weed seeds per 1000 grams of seed. The results of the study produced the following average values: seed purity - 99.72%, 1000-seed weight - 67.59g, germination energy - 88.2%, germination - 91.8%, seed moisture - 8.3%. There were not found weeds seeds as well as pathogens on the seed samples, these values are all within the legally prescribed limits.

  6. New design of experiment combined with UV-Vis spectroscopy for extraction and estimation of polyphenols from Basil seeds, Red seeds, Sesame seeds and Ajwan seeds.

    Science.gov (United States)

    Mabood, Fazal; Gilani, Syed Abdullah; Hussain, Javid; Alshidani, Sulaiman; Alghawi, Said; Albroumi, Mohammed; Alameri, Saif; Jabeen, Farah; Hussain, Zahid; Al-Harrasi, Ahmed; Al Abri, Zahra K M; Farooq, Saima; Naureen, Zakira; Hamaed, Ahmad; Rasul Jan, M; Shah, Jasmin

    2017-05-05

    New experimental designs for the extraction of polyphenols from different seeds including Basil seed, Red seed, Sesame seeds and Ajwan seeds were investigated. Four variables the concentration and volume of methanol and NaOH solutions as well as the temperature and time of extraction were varied to see their effect on total phenol extraction. The temperature was varied in the range from 25°C to 200°C while the time in the range from 30 to 200minutes. Response surface methodology was used to optimize the extraction parameters. The estimation of polyphenols was measured through phenols reduction UV-Vis spectroscopic method of phosphotungstic-phosphomolybdic acids (Folin-Ciocalteu's reagent). Calibration curve was made by using tannic acid as a polyphenols standard in the concentration range from 0.1 to 10ppm. The regression line obtained shows the value of correlation coefficient i.e. R=0.930 and Root mean square error of cross validation (RMSEC) value of 0.0654. The Basil seeds were found containing the highest amount of total phenols i.e. 785.76mg/100g. While the Sesame seeds having the least amount i.e. 33.08mg/100g. The Ajwan seeds and the Red seeds are containing the medium amounts i.e. 379mg/100g and 220.54mg/100g respectively. Copyright © 2017 Elsevier B.V. All rights reserved.

  7. New design of experiment combined with UV-Vis spectroscopy for extraction and estimation of polyphenols from Basil seeds, Red seeds, Sesame seeds and Ajwan seeds

    Science.gov (United States)

    Mabood, Fazal; Gilani, Syed Abdullah; Hussain, Javid; Alshidani, Sulaiman; Alghawi, Said; Albroumi, Mohammed; Alameri, Saif; Jabeen, Farah; Hussain, Zahid; Al-Harrasi, Ahmed; Al Abri, Zahra K. M.; Farooq, Saima; Naureen, Zakira; Hamaed, Ahmad; Rasul Jan, M.; Shah, Jasmin

    2017-05-01

    New experimental designs for the extraction of polyphenols from different seeds including Basil seed, Red seed, Sesame seeds and Ajwan seeds were investigated. Four variables the concentration and volume of methanol and NaOH solutions as well as the temperature and time of extraction were varied to see their effect on total phenol extraction. The temperature was varied in the range from 25 °C to 200 °C while the time in the range from 30 to 200 minutes. Response surface methodology was used to optimize the extraction parameters. The estimation of polyphenols was measured through phenols reduction UV-Vis spectroscopic method of phosphotungstic-phosphomolybdic acids (Folin-Ciocalteu's reagent). Calibration curve was made by using tannic acid as a polyphenols standard in the concentration range from 0.1 to 10 ppm. The regression line obtained shows the value of correlation coefficient i.e. R = 0.930 and Root mean square error of cross validation (RMSEC) value of 0.0654. The Basil seeds were found containing the highest amount of total phenols i.e. 785.76 mg/100 g. While the Sesame seeds having the least amount i.e. 33.08 mg/100 g. The Ajwan seeds and the Red seeds are containing the medium amounts i.e. 379 mg/100 g and 220.54 mg/100 g respectively.

  8. FRW Cosmological Perturbations in Massive Bigravity

    CERN Document Server

    Comelli, D; Pilo, L

    2014-01-01

    Cosmological perturbations of FRW solutions in ghost free massive bigravity, including also a second matter sector, are studied in detail. At early time, we find that sub horizon exponential instabilities are unavoidable and they lead to a premature departure from the perturbative regime of cosmological perturbations.

  9. Seeds of hope, seeds of despair: towards a political economy of the seed industry in southern Africa.

    Science.gov (United States)

    Zerbe, N

    2001-01-01

    The seed industry in Southern Africa has been radically transformed by a policy of liberalisation and privatisation started under structural adjustment. Traditionally under the domain of parastatals, seed research, production and distribution has been criticised for failing to provide modern variety seed to smallholder farmers. However, the private companies which have stepped in to replace seed parastatals in southern Africa have proven no more effective in meeting the demands of smallholders. The Trade Related Intellectual Property Rights (TRIPs) Agreement, concluded in 1994 as part of the Uruguay Rounds of GATT negotiations, as well as certain biotechnological innovations such as Terminator or Traitor technologies, threaten to further undermine local seed production and consumption by destroying the informal seed sector so central to agricultural production in the region. What alternatives exist? The success of Zimbabwe's maize seed network offers some insight. Resting on a unique relationship between government and nationally based producer co-operatives, Zimbabwe's maize programme was able to provide nearly every farmer in the country with hybrid maize suited for local growing conditions.

  10. Removal of Malachite Green Dye by Mangifera indica Seed Kernel Powder

    Science.gov (United States)

    Singh, Dilbagh; Sowmya, V.; Abinandan, S.; Shanthakumar, S.

    2017-11-01

    In this study, batch experiments were carried out to study the adsorption of Malachite green dye from aqueous solution by Mangifera indica (mango) seed kernel powder. The mango seed kernel powder was characterized by Fourier transform infrared spectroscopy and scanning electron microscopy. Effect of various parameters including pH, contact time, adsorbent dosage, initial dye concentration and temperature on adsorption capacity of the adsorbent was observed and the optimized condition for maximum dye removal was identified. Maximum percentage removal of 96% was achieved with an adsorption capacity of 22.8 mg/g at pH 6 with an initial concentration of 100 mg/l. The equilibrium data were examined to fit the Langmuir and Freundlich isotherm models. Thermodynamic parameters for the adsorption process were also calculated.

  11. Lack of caching of direct-seeded Douglas fir seeds by deer mice

    International Nuclear Information System (INIS)

    Sullivan, T.P.

    1978-01-01

    Seed caching by deer mice was investigated by radiotagging seeds in forest and clear-cut areas in coastal British Columbia. Deer mice tend to cache very few Douglas fir seeds in the fall when the seed is uniformly distributed and is at densities comparable with those used in direct-seeding programs. (author)

  12. Propagation of perturbations for a sixth-order thin film equation

    Directory of Open Access Journals (Sweden)

    Zhenbang Li

    2012-07-01

    Full Text Available We consider an initial-boundary problem for a sixth-order thin film equation, which arises in the industrial application of the isolation oxidation of silicon. Relying on some necessary uniform estimates of the approximate solutions, we prove the existence of radial symmetric solutions to this problem in the two-dimensional space. The nonnegativity and the finite speed of propagation of perturbations of solutions are also discussed.

  13. Modifying mixing and instability growth through the adjustment of initial conditions in a high-energy-density counter-propagating shear experiment on OMEGA

    International Nuclear Information System (INIS)

    Merritt, E. C.; Doss, F. W.; Loomis, E. N.; Flippo, K. A.; Kline, J. L.

    2015-01-01

    Counter-propagating shear experiments conducted at the OMEGA Laser Facility have been evaluating the effect of target initial conditions, specifically the characteristics of a tracer foil located at the shear boundary, on Kelvin-Helmholtz instability evolution and experiment transition toward nonlinearity and turbulence in the high-energy-density (HED) regime. Experiments are focused on both identifying and uncoupling the dependence of the model initial turbulent length scale in variable-density turbulence models of k-ϵ type on competing physical instability seed lengths as well as developing a path toward fully developed turbulent HED experiments. We present results from a series of experiments controllably and independently varying two initial types of scale lengths in the experiment: the thickness and surface roughness (surface perturbation scale spectrum) of a tracer layer at the shear interface. We show that decreasing the layer thickness and increasing the surface roughness both have the ability to increase the relative mixing in the system, and thus theoretically decrease the time required to begin transitioning to turbulence in the system. We also show that we can connect a change in observed mix width growth due to increased foil surface roughness to an analytically predicted change in model initial turbulent scale lengths

  14. Singular Perturbations and Time Scales in Modeling and Control of Dynamic Systems,

    Science.gov (United States)

    1980-11-01

    rTrp) (43) results in the initial value singularly perturbed matrix differential equations * providing there exist fta ’) and rT(p) uniquely...ReA(Af)ɘ then A1 is D-stable. Let us conditions may be more difficult. Our problem is assume that the network has n, inductors and nc to fmd

  15. Evaluation of the soil-seed environment through computerized tomography

    International Nuclear Information System (INIS)

    Modolo, Alcir Jose; Fernandes, Haroldo Carlos; Schaefer, Carlos Ernesto G.R.; Santos, Nerilson Terra; Silveira, Joao Cleber Modernel da

    2008-01-01

    The physical conditioning of the soil around seeds is of great importance for an adequate initial development of a crop, ensuring a healthy plant population. A suitable soil-seed contact is a prerequisite for a fast crop germination and good establishment. In this study, computerized tomography of millimeter resolution was used to determine the soil-seed environment in a no tillage system, immediately after soybean planting. A split plot design was used, in which the plots consisted of three contents of soil water, corresponding to 0.27; 0,31 and 0.36 kg kg -1 , respectively, and the split plots of four load levels applied by the compaction wheel, corresponding to 0, 50, 90 and 140 N, respectively. It was used a random block design, with four replications. The medium soil density in the seed area and the medium density profile in the sowing furrow were evaluated. According to the results, it may be concluded that: the loads applied by the compaction wheel increased soil density at the vertical planting level beneath planting depth as compared with values obtained before planting, and; the combination of wheel loads and soil water contents did not influence the mean soil density in the seed area. (author)

  16. Cosmological perturbations in antigravity

    Science.gov (United States)

    Oltean, Marius; Brandenberger, Robert

    2014-10-01

    We compute the evolution of cosmological perturbations in a recently proposed Weyl-symmetric theory of two scalar fields with oppositely signed conformal couplings to Einstein gravity. It is motivated from the minimal conformal extension of the standard model, such that one of these scalar fields is the Higgs while the other is a new particle, the dilaton, introduced to make the Higgs mass conformally symmetric. At the background level, the theory admits novel geodesically complete cyclic cosmological solutions characterized by a brief period of repulsive gravity, or "antigravity," during each successive transition from a big crunch to a big bang. For simplicity, we consider scalar perturbations in the absence of anisotropies, with potential set to zero and without any radiation. We show that despite the necessarily wrong-signed kinetic term of the dilaton in the full action, these perturbations are neither ghostlike nor tachyonic in the limit of strongly repulsive gravity. On this basis, we argue—pending a future analysis of vector and tensor perturbations—that, with respect to perturbative stability, the cosmological solutions of this theory are viable.

  17. Gauge-invariant cosmological density perturbations

    International Nuclear Information System (INIS)

    Sasaki, Misao.

    1986-06-01

    Gauge-invariant formulation of cosmological density perturbation theory is reviewed with special emphasis on its geometrical aspects. Then the gauge-invariant measure of the magnitude of a given perturbation is presented. (author)

  18. Twisting perturbed parafermions

    Directory of Open Access Journals (Sweden)

    A.V. Belitsky

    2017-07-01

    Full Text Available The near-collinear expansion of scattering amplitudes in maximally supersymmetric Yang–Mills theory at strong coupling is governed by the dynamics of stings propagating on the five sphere. The pentagon transitions in the operator product expansion which systematize the series get reformulated in terms of matrix elements of branch-point twist operators in the two-dimensional O(6 nonlinear sigma model. The facts that the latter is an asymptotically free field theory and that there exists no local realization of twist fields prevents one from explicit calculation of their scaling dimensions and operator product expansion coefficients. This complication is bypassed making use of the equivalence of the sigma model to the infinite-level limit of WZNW models perturbed by current–current interactions, such that one can use conformal symmetry and conformal perturbation theory for systematic calculations. Presently, to set up the formalism, we consider the O(3 sigma model which is reformulated as perturbed parafermions.

  19. Effect of Hydrotherapy on Static and Dynamic Balance in Older Adults: Comparison of Perturbed and Non-Perturbed Programs

    Directory of Open Access Journals (Sweden)

    Elham Azimzadeh

    2013-01-01

    Full Text Available Objectives: Falling is a main cause of mortality in elderly. Balance training exercises can help to prevent falls in older adults. According to the principle of specificity of training, the perturbation-based trainings are more similar to the real world. So these training programs can improve balance in elderly. Furthermore, exercising in an aquatic environment can reduce the limitations for balance training rather than a non-aquatic on. The aim of this study is comparing the effectiveness of perturbed and non-perturbed balance training programs in water on static and dynamic balance in aforementioned population group. Methods & Materials: 37 old women (age 80-65, were randomized to the following groups: perturbation-based training (n=12, non-perturbation-based training (n=12 and control (n=13 groups. Static and dynamic balance had been tested before and after the eight weeks of training by the postural stability test of the Biodex balance system using dynamic (level 4 and static platform. The data were analyzed by one sample paired t-test, Independent t-test and ANOVA. Results: There was a significant improvement for all indexes of static and dynamic balance in perturbation-based training (P<0.05. However, in non-perturbed group, all indexes were improved except ML (P<0.05. ANOVA showed that perturbed training was more effective than non-perturbed training on both static and dynamic balances. Conclusion: The findings confirmed the specificity principle of training. Although balance training can improve balance abilities, these kinds of trainings are not such specific for improving balance neuromuscular activities.The perturbation-based trainings can activate postural compensatory responses and reduce falling risk. According to results, we can conclude that hydrotherapy especially with perturbation-based programs will be useful for rehabilitation interventions in elderly .

  20. Heirloom biodynamic seeds network rescue, conservation and multiplication of local seeds in Brazil

    OpenAIRE

    Jovchelevich, Pedro

    2014-01-01

    Structuring a network organic and biodynamic seed involving farmers in the central- southern Brazil. Training, participatory breeding, edition of publications, fairs of exchange seeds, a processing unit and assessment of seed quality, commercial seed multiplication with emphasis on vegetables. This network has garanteed the autonomy of farmers in seed production and enriched agrobiodiversity through exchanges of seed.

  1. combining high seed number and weight to improve seed yield

    African Journals Online (AJOL)

    ACSS

    ABSTRACT. Increasing seed size and seed weight is an important trait for trade, yield component and adaptation of chickpea ... determining yield or quality, and the development of rapid and ..... C.G. 1981. Control of seed growth in soybeans.

  2. Research on perturbation based Monte Carlo reactor criticality search

    International Nuclear Information System (INIS)

    Li Zeguang; Wang Kan; Li Yangliu; Deng Jingkang

    2013-01-01

    Criticality search is a very important aspect in reactor physics analysis. Due to the advantages of Monte Carlo method and the development of computer technologies, Monte Carlo criticality search is becoming more and more necessary and feasible. Traditional Monte Carlo criticality search method is suffered from large amount of individual criticality runs and uncertainty and fluctuation of Monte Carlo results. A new Monte Carlo criticality search method based on perturbation calculation is put forward in this paper to overcome the disadvantages of traditional method. By using only one criticality run to get initial k_e_f_f and differential coefficients of concerned parameter, the polynomial estimator of k_e_f_f changing function is solved to get the critical value of concerned parameter. The feasibility of this method was tested. The results show that the accuracy and efficiency of perturbation based criticality search method are quite inspiring and the method overcomes the disadvantages of traditional one. (authors)

  3. Perturbations of the Yang-Mills field in the universe

    International Nuclear Information System (INIS)

    Zhao Wen

    2009-01-01

    It has been suggested that the Yang-Mills (YM) field can be a kind of candidate for the inflationary field at high energy scales or dark energy at very low energy scales, which can naturally give the equation of state -1 -2 , from which it follows that the equation of state of the YM field always goes to -1, independent of the initial conditions. By solving the first order Einstein equations and the YM field equations, we find that in the YM field inflationary models, the scale-invariant primordial perturbation power spectrum cannot be generated. Therefore, only using this kind of YM field is not enough to account for inflationary sources. However, as a kind of candidate for dark energy, the YM field has the 'sound speed' cs 2 S = -1/3 < 0, which makes the perturbation oe have a damping behavior at large scales. This provides a way to distinguish the YM field dark energy models from other kinds of models. (research papers)

  4. Quantum inflaton, primordial metric perturbations and CMB fluctuations

    International Nuclear Information System (INIS)

    Cao, F J

    2007-01-01

    We compute the primordial scalar, vector and tensor metric perturbations arising from quantum field inflation. Quantum field inflation takes into account the nonperturbative quantum dynamics of the inflaton consistently coupled to the dynamics of the (classical) cosmological metric. For chaotic inflation, the quantum treatment avoids the unnatural requirements of an initial state with all the energy in the zero mode. For new inflation it allows a consistent treatment of the explosive particle production due to spinodal instabilities. Quantum field inflation (under conditions that are the quantum analog of slow roll) leads, upon evolution, to the formation of a condensate starting a regime of effective classical inflation. We compute the primordial perturbations taking the dominant quantum effects into account. The results for the scalar, vector and tensor primordial perturbations are expressed in terms of the classical inflation results. For a N-component field in a O(N) symmetric model, adiabatic fluctuations dominate while isocurvature or entropy fluctuations are negligible. The results agree with the current WMAP observations and predict corrections to the power spectrum in classical inflation. Such corrections are estimated to be of the order of m 2 /[NH 2 ] where m is the inflaton mass and H the Hubble constant at horizon crossing. This turns to be about 4% for the cosmologically relevant scales. This quantum field treatment of inflation provides the foundations to the classical inflation and permits to compute quantum corrections to it

  5. Seed producer cooperatives in the Ethiopian seed sector and their role in seed supply improvement: A review

    NARCIS (Netherlands)

    Sisay, D.T.; Verhees, F.J.H.M.; Trijp, van J.C.M.

    2017-01-01

    The role of seed producer cooperatives (SPCs) in the Ethiopian seed sector and their contribution to seed supply improvement have received attention from researchers, policymakers, and development partners. However, limited work has been done in reviewing and documenting their involvement in the

  6. Multiplicative perturbations of local C-semigroups

    Indian Academy of Sciences (India)

    In this paper, we establish some left and right multiplicative perturbation theorems concerning local -semigroups when the generator of a perturbed local -semigroup S ( ⋅ ) may not be densely defined and the perturbation operator is a bounded linear operator from D ( A ) ¯ into () such that = on D ( A ) ¯ ...

  7. Multiplicative perturbations of local C-semigroups

    Indian Academy of Sciences (India)

    2016-08-26

    Aug 26, 2016 ... In this paper, we establish some left and right multiplicative perturbation theorems concerning local -semigroups when the generator of a perturbed local -semigroup S(⋅) may not be densely defined and the perturbation operator is a bounded linear operator from ¯D(A) into () such that = ...

  8. genetics and inheritance of seed dormancy inflicted by seed

    African Journals Online (AJOL)

    Mgina

    ABSTRACT. The study was undertaken to investigate the genetic mode of inheritance of dormancy imposed by the hull (seed coat) in rice seeds. Freshly harvested seeds of parents, F1 and F2 populations of a cross between a dormant cultivar Kisegese and non-dormant strain K2004 were used. Germination test of the ...

  9. Perturbative QCD (1/3)

    CERN Multimedia

    CERN. Geneva

    2013-01-01

    Perturbative QCD is the general theoretical framework for describing hard scattering processes yielding multiparticle production at hadron colliders. In these lectures, we shall introduce fundamental features of perturbative QCD and describe its application to several high energy collider processes, including jet production in electron-positron annihilation, deep inelastic scattering, Higgs boson and gauge boson production at the LHC.

  10. A comparison of nodular defect seed geometeries from different deposition techniques

    International Nuclear Information System (INIS)

    Stolz, C.J.; Tench, R.J.; Kozlowski, M.R.; Fornier, A.

    1995-01-01

    A focused ion-beam milling instrument commonly utilized in the semiconductor industry for failure analysis and IC repair, is capable of cross-sectioning nodular defects. Utilizing the instrument's scanning on beam, high-resolution imaging of the seeds that initiate nodular defect growth is possible. In an attempt to understand the origins of these seeds, HfO 2 /SiO 2 and Ta 2 O 5 /SiO 2 coatings were prepared by a variety of coating vendors and different deposition processes including e-beam, magnetron sputtering, and ion beam sputtering. By studying the shape, depth, and composition of the seed, inferences of its origin can be drawn. The boundaries between the nodule and thin film provide insight into the mechanical stability of the nodule. Significant differences in the seed composition, geometry of nodular growth and mechanical stability of the defects for sputtered versus e-beam coatings are reported. Differences in seed shape were also observed from different coating vendors using e-beam deposition of HfO 2 /SiO 2 coatings

  11. Long wavelength limit of evolution of cosmological perturbations in the universe where scalar fields and fluids coexist

    International Nuclear Information System (INIS)

    Hamazaki, Takashi

    2008-01-01

    We present the LWL formula which represents the long wavelength limit of the solutions of evolution equations of cosmological perturbations in terms of the exactly homogeneous solutions in the most general case where multiple scalar fields and multiple perfect fluids coexist. We find the conserved quantity which has origin in the adiabatic decaying mode, and by regarding this quantity as the source term we determine the correction term which corrects the discrepancy between the exactly homogeneous perturbations and the k→0 limit of the evolutions of cosmological perturbations. This LWL formula is useful for investigating the evolutions of cosmological perturbations in the early stage of our universe such as reheating after inflation and the curvaton decay in the curvaton scenario. When we extract the long wavelength limits of evolutions of cosmological perturbations from the exactly homogeneous perturbations by the LWL formula, it is more convenient to describe the corresponding exactly homogeneous system with not the cosmological time but the scale factor as the evolution parameter. By applying the LWL formula to the reheating model and the curvaton model with multiple scalar fields and multiple radiation fluids, we obtain the S formula representing the final amplitude of the Bardeen parameter in terms of the initial adiabatic and isocurvature perturbations

  12. Initial States: IR and Collinear Divergences

    International Nuclear Information System (INIS)

    Lavelle, Martin; McMullan, David

    2007-01-01

    The standard approach to the infra-red problem is to use the Bloch-Nordsieck trick to handle soft divergences and the Lee-Nauenberg (LN) theorem for collinear singularities. We show that this is inconsistent in the presence of massless initial particles. Furthermore, we show that using the LN theorem with such initial states introduces a non-convergent infinite series of diagrams at any fixed order in perturbation theory

  13. Geometric Hamiltonian structures and perturbation theory

    International Nuclear Information System (INIS)

    Omohundro, S.

    1984-08-01

    We have been engaged in a program of investigating the Hamiltonian structure of the various perturbation theories used in practice. We describe the geometry of a Hamiltonian structure for non-singular perturbation theory applied to Hamiltonian systems on symplectic manifolds and the connection with singular perturbation techniques based on the method of averaging

  14. The effect of fruit maturity on the physiological quality and conservation of Jatropha curcas seeds

    Directory of Open Access Journals (Sweden)

    Laércio Junio da Silva

    Full Text Available ABSTRACT The aim of this study was to evaluate the effect of fruit maturation stage on the physiological quality of J. curcas seeds during storage. Thus, seeds were extracted from fruits harvested at different maturity stages based on external color, i.e., yellow, yellow-brown and brown (dry fruits. After natural drying, the seeds were packed in Kraft paper bag and stored for 18 months at laboratory environment. Initially and every three months, the seeds were evaluated for moisture content, germination, first count of germination, accelerated aging, cold test, electrical conductivity and emergence. There was reduction in seed physiological quality, with decrease in germination and vigor, especially after nine months of storage. The seeds extracted from yellow and yellow-brown fruits are the most vigorous and can be stored for up to nine months without loss of physiological quality.

  15. Seeds of confusion : the impact of policies on seed systems

    OpenAIRE

    Louwaars, N.P.

    2007-01-01

    Seed is basic to crop production. Next to its importance in production, food security and rural development, seed is a key element in many debates about technology development and transfer, biodiversity, globalisation and equity. The sustainable availability of good quality seed is thus an important development issue. This study deals with the impact different types of regulation have on how farmers access seed. I have analysed current regulatory frameworks in terms of their impact on differe...

  16. Wheat seed system in Ethiopia: Farmers' varietal perception, seed sources, and seed management

    NARCIS (Netherlands)

    Bishaw, Z.; Struik, P.C.; Gastel, van A.J.G.

    2010-01-01

    Knowledge and information on farmers' perception and its influence on adoption of modern wheat varieties, awareness and source of new wheat production technology, wheat seed sources, and on-farm seed-management practices remain sporadic in Ethiopia. This study was conducted to understand the

  17. Physicochemical Evaluation of Seeds and Oil of Nontraditional Oil Seeds

    Directory of Open Access Journals (Sweden)

    Adam Ismail Ahmed

    2015-08-01

    Full Text Available The present work was conducted in the Laboratory of Biochemistry and Food science department, Faculty of Natural Resources and Environmental Studies, University of Kordofan, in order to evaluate some nontraditional oil seeds these are i.e. Marula (Sclerocarya birrea, Roselle (Hibiscus sabdariffa L. seeds and Christ’s thorn (Zizyphus spina-christi seeds. The seeds of the roselle and Christ’s thorn fruits were procured from Elobeid local market, North Kordofan State, while marula fruits were obtained from Elnuhod, West Kordofan State. The proximate composition of the seeds, cake and christ’s thorn pulp was done. Some chemical and physical properties were performed for the extracted oil. The results revealed that proximate composition of the seeds and cake differ statistically among the studied materials. Significant differences were observed among the oil extracted from these species; moreover, these oils differ significantly in color and viscosity only.

  18. Robotic seeding

    DEFF Research Database (Denmark)

    Pedersen, Søren Marcus; Fountas, Spyros; Sørensen, Claus Aage Grøn

    2017-01-01

    Agricultural robotics has received attention for approximately 20 years, but today there are only a few examples of the application of robots in agricultural practice. The lack of uptake may be (at least partly) because in many cases there is either no compelling economic benefit......, or there is a benefit but it is not recognized. The aim of this chapter is to quantify the economic benefits from the application of agricultural robots under a specific condition where such a benefit is assumed to exist, namely the case of early seeding and re-seeding in sugar beet. With some predefined assumptions...... with regard to speed, capacity and seed mapping, we found that among these two technical systems both early seeding with a small robot and re-seeding using a robot for a smaller part of the field appear to be financially viable solutions in sugar beet production....

  19. Non-perturbative effects in supersymmetry

    International Nuclear Information System (INIS)

    Veneziano, G.

    1987-01-01

    Some non perturbative aspects of globally supersymmetric (SUSY) gauge theories are discussed. These share with their non-supersymmetric analogues interesting non perturbative features, such as the spontaneous breaking of chiral symmetries via condensates. What is peculiar about supersymmetric theories, however, is that one is able to say a lot about non-perturbative effects even without resorting to elaborate numerical calculations: general arguments, supersymmetric and chiral Ward identities and analytic, dynamical calculations will turn out to effectively determine most of the supersymmetric vacuum properties. 28 references, 5 figures

  20. Seeds of confusion : the impact of policies on seed systems

    NARCIS (Netherlands)

    Louwaars, N.P.

    2007-01-01

    Seed is basic to crop production. Next to its importance in production, food security and rural development, seed is a key element in many debates about technology development and transfer, biodiversity, globalisation and equity. The sustainable availability of good quality seed is thus an important

  1. Seed mass and mast seeding enhance dispersal by a neotropical scatter-hoarding rodent

    NARCIS (Netherlands)

    Jansen, P.A.; Bongers, F.J.J.M.; Hemerik, L.

    2004-01-01

    Many tree species that depend on scatter-hoarding animals for seed dispersal produce massive crops of large seeds at irregular intervals. Mast seeding and large seed size in these species have been explained as adaptations to increase animal dispersal and reduce predation. We studied how seed size

  2. Seed Placement in Permanent Breast Seed Implant Brachytherapy: Are Concerns Over Accuracy Valid?

    Energy Technology Data Exchange (ETDEWEB)

    Morton, Daniel, E-mail: dmorton@bccancer.bc.ca [Department of Medical Physics, BC Cancer Agency, Centre for the Southern Interior, Kelowna, British Columbia (Canada); Department of Physics and Astronomy, University of Victoria, Victoria, British Columbia (Canada); Hilts, Michelle [Department of Medical Physics, BC Cancer Agency, Centre for the Southern Interior, Kelowna, British Columbia (Canada); Department of Physics and Astronomy, University of Victoria, Victoria, British Columbia (Canada); Batchelar, Deidre [Department of Medical Physics, BC Cancer Agency, Centre for the Southern Interior, Kelowna, British Columbia (Canada); Crook, Juanita [Department of Radiation Oncology, BC Cancer Agency, Centre for the Southern Interior, Kelowna, British Columbia (Canada)

    2016-07-01

    Purpose: To evaluate seed placement accuracy in permanent breast seed implant brachytherapy (PBSI), to identify any systematic errors and evaluate their effect on dosimetry. Methods and Materials: Treatment plans and postimplant computed tomography scans for 20 PBSI patients were spatially registered and used to evaluate differences between planned and implanted seed positions, termed seed displacements. For each patient, the mean total and directional seed displacements were determined in both standard room coordinates and in needle coordinates relative to needle insertion angle. Seeds were labeled according to their proximity to the anatomy within the breast, to evaluate the influence of anatomic regions on seed placement. Dosimetry within an evaluative target volume (seroma + 5 mm), skin, breast, and ribs was evaluated to determine the impact of seed placement on the treatment. Results: The overall mean (±SD) difference between implanted and planned positions was 9 ± 5 mm for the aggregate seed population. No significant systematic directional displacements were observed for this whole population. However, for individual patients, systematic displacements were observed, implying that intrapatient offsets occur during the procedure. Mean displacements for seeds in the different anatomic areas were not found to be significantly different from the mean for the entire seed population. However, small directional trends were observed within the anatomy, potentially indicating some bias in the delivery. Despite observed differences between the planned and implanted seed positions, the median (range) V{sub 90} for the 20 patients was 97% (66%-100%), and acceptable dosimetry was achieved for critical structures. Conclusions: No significant trends or systematic errors were observed in the placement of seeds in PBSI, including seeds implanted directly into the seroma. Recorded seed displacements may be related to intrapatient setup adjustments. Despite observed seed

  3. Seed germination studies on Gymnacranthera canarica (King Warb. - a Vulnerable tree species of a highly threatened Myristica swamp ecosystem

    Directory of Open Access Journals (Sweden)

    K. Keshavachandra

    2016-07-01

    Full Text Available Gymnacranthera canarica (King Warb. is an exclusive Myristica swamp species endemic to the Western Ghats.  The Myristica swamp is a Critically Endangered ecosystem.  Studies were carried out to assess the viability, germination and storage behaviour of Gymnacranthera canarica seeds.  In the present study, it was observed that seeds have shown an initiation of germination after two weeks.  A maximum of 90% germination was recorded when the initial moisture content was 38.04 ± 1.75 %.  A decreased percentage (3% was observed when the moisture content reached 14.26 ± 2.3 after 70 days of storage.  Seeds failed to germinate beyond this moisture level.  A desiccation study showed recalcitrant behaviour and seeds can be stored in lab conditions for up to two and half months.

  4. Local perturbations perturb—exponentially–locally

    International Nuclear Information System (INIS)

    De Roeck, W.; Schütz, M.

    2015-01-01

    We elaborate on the principle that for gapped quantum spin systems with local interaction, “local perturbations [in the Hamiltonian] perturb locally [the groundstate].” This principle was established by Bachmann et al. [Commun. Math. Phys. 309, 835–871 (2012)], relying on the “spectral flow technique” or “quasi-adiabatic continuation” [M. B. Hastings, Phys. Rev. B 69, 104431 (2004)] to obtain locality estimates with sub-exponential decay in the distance to the spatial support of the perturbation. We use ideas of Hamza et al. [J. Math. Phys. 50, 095213 (2009)] to obtain similarly a transformation between gapped eigenvectors and their perturbations that is local with exponential decay. This allows to improve locality bounds on the effect of perturbations on the low lying states in certain gapped models with a unique “bulk ground state” or “topological quantum order.” We also give some estimate on the exponential decay of correlations in models with impurities where some relevant correlations decay faster than one would naively infer from the global gap of the system, as one also expects in disordered systems with a localized groundstate

  5. Perturbation theory in large order

    International Nuclear Information System (INIS)

    Bender, C.M.

    1978-01-01

    For many quantum mechanical models, the behavior of perturbation theory in large order is strikingly simple. For example, in the quantum anharmonic oscillator, which is defined by -y'' + (x 2 /4 + ex 4 /4 - E) y = 0, y ( +- infinity) = 0, the perturbation coefficients, A/sub n/, in the expansion for the ground-state energy, E(ground state) approx. EPSILON/sub n = 0//sup infinity/ A/sub n/epsilon/sup n/, simplify dramatically as n → infinity: A/sub n/ approx. (6/π 3 )/sup 1/2/(-3)/sup n/GAMMA(n + 1/2). Methods of applied mathematics are used to investigate the nature of perturbation theory in quantum mechanics and show that its large-order behavior is determined by the semiclassical content of the theory. In quantum field theory the perturbation coefficients are computed by summing Feynman graphs. A statistical procedure in a simple lambda phi 4 model for summing the set of all graphs as the number of vertices → infinity is presented. Finally, the connection between the large-order behavior of perturbation theory in quantum electrodynamics and the value of α, the charge on the electron, is discussed. 7 figures

  6. Some remarks on perturbation in flame photometry; Quelques remarques sur les perturbations dans la photometrie de flamme

    Energy Technology Data Exchange (ETDEWEB)

    Malinowski, J [Commissariat a l' Energie Atomique, Saclay (France).Centre d' Etudes Nucleaires

    1960-07-01

    After classifying the various types of perturbations, the author attempts to explain their causes. He then gives examples of possibilities of suppressing them. (author) [French] Ayant classe les divers types de perturbations en categories, l'auteur essaie d'expliquer les causes de ces perturbations. Il donne ensuite des exemples de possibilites de les supprimer. (auteur)

  7. Consistent individual differences in seed disperser quality in a seed-eating fish

    NARCIS (Netherlands)

    Pollux, Bart J.A.

    2017-01-01

    Animal-mediated seed dispersal (zoochory) is considered to be an important mechanism regulating biological processes at larger spatial scales. To date, intra-specific variation in seed disperser quality within seed-dispersing animals has not been studied. Here, I employed seed feeding trials to

  8. Interactions between seed traits and digestive processes determine the germinability of bird-dispersed seeds.

    Science.gov (United States)

    Kleyheeg, Erik; Claessens, Mascha; Soons, Merel B

    2018-01-01

    Waterbirds disperse a wide range of plant seeds via their guts, promoting biotic connectivity between isolated habitat patches. However, the intensity of digestive forces encountered by seeds, and therefore their potential to survive digestive tract passage, varies within and between waterbird species. Here, we investigate under controlled conditions how the interaction between seed traits and digestive strategies affect the germinability of seeds following waterbird-mediated dispersal. We exposed seeds of 30 wetland plant species to the main digestive processes in the dabbling duck digestive system: mechanical, chemical and intestinal digestion. These were simulated by 1) a pressure test and scarification treatment, 2) incubation in simulated gastric juice, and 3) incubation in intestinal contents of culled mallards (Anas platyrhynchos). We evaluated their separate and combined effects on seed germination, and identified the role of seed size and seed coat traits in resisting the digestive forces. Seeds were generally resistant to separate digestive processes, but highly sensitive to a combination. Resistance to mechanical break-down was reduced by up to 80% by chemical pre-treatment, especially for seeds with permeable coats. Scarified seeds were 12-17% more vulnerable to chemical and intestinal digestive processes than undamaged seeds. Large seeds and seeds with thin, permeable coats were particularly sensitive to chemical and intestinal digestion. These results indicate that efficient digestion of seeds requires multiple digestive processes. The gizzard, responsible for mechanical digestion, plays a key role in seed survival. Omnivorous birds, which have relatively light gizzards compared to pure herbivores or granivores, are thus most likely to disperse seeds successfully. Regardless of digestive strategy, small seeds with tough seed coats are most resistant to digestion and may be adapted to endozoochorous dispersal by waterbirds.

  9. Interactions between seed traits and digestive processes determine the germinability of bird-dispersed seeds

    Science.gov (United States)

    Soons, Merel B.

    2018-01-01

    Waterbirds disperse a wide range of plant seeds via their guts, promoting biotic connectivity between isolated habitat patches. However, the intensity of digestive forces encountered by seeds, and therefore their potential to survive digestive tract passage, varies within and between waterbird species. Here, we investigate under controlled conditions how the interaction between seed traits and digestive strategies affect the germinability of seeds following waterbird-mediated dispersal. We exposed seeds of 30 wetland plant species to the main digestive processes in the dabbling duck digestive system: mechanical, chemical and intestinal digestion. These were simulated by 1) a pressure test and scarification treatment, 2) incubation in simulated gastric juice, and 3) incubation in intestinal contents of culled mallards (Anas platyrhynchos). We evaluated their separate and combined effects on seed germination, and identified the role of seed size and seed coat traits in resisting the digestive forces. Seeds were generally resistant to separate digestive processes, but highly sensitive to a combination. Resistance to mechanical break-down was reduced by up to 80% by chemical pre-treatment, especially for seeds with permeable coats. Scarified seeds were 12–17% more vulnerable to chemical and intestinal digestive processes than undamaged seeds. Large seeds and seeds with thin, permeable coats were particularly sensitive to chemical and intestinal digestion. These results indicate that efficient digestion of seeds requires multiple digestive processes. The gizzard, responsible for mechanical digestion, plays a key role in seed survival. Omnivorous birds, which have relatively light gizzards compared to pure herbivores or granivores, are thus most likely to disperse seeds successfully. Regardless of digestive strategy, small seeds with tough seed coats are most resistant to digestion and may be adapted to endozoochorous dispersal by waterbirds. PMID:29614085

  10. 7 CFR 201.33 - Seed in bulk or large quantities; seed for cleaning or processing.

    Science.gov (United States)

    2010-01-01

    ... quantities; seed for cleaning or processing. (a) In the case of seed in bulk, the information required under... seeds. (b) Seed consigned to a seed cleaning or processing establishment, for cleaning or processing for... pertaining to such seed show that it is “Seed for processing,” or, if the seed is in containers and in...

  11. Perturbation theory of effective Hamiltonians

    International Nuclear Information System (INIS)

    Brandow, B.H.

    1975-01-01

    This paper constitutes a review of the many papers which have used perturbation theory to derive ''effective'' or ''model'' Hamiltonians. It begins with a brief review of nondegenerate and non-many-body perturbation theory, and then considers the degenerate but non-many-body problem in some detail. It turns out that the degenerate perturbation problem is not uniquely defined, but there are some practical criteria for choosing among the various possibilities. Finally, the literature dealing with the linked-cluster aspects of open-shell many-body systems is reviewed. (U.S.)

  12. A view on coupled cluster perturbation theory using a bivariational Lagrangian formulation.

    Science.gov (United States)

    Kristensen, Kasper; Eriksen, Janus J; Matthews, Devin A; Olsen, Jeppe; Jørgensen, Poul

    2016-02-14

    We consider two distinct coupled cluster (CC) perturbation series that both expand the difference between the energies of the CCSD (CC with single and double excitations) and CCSDT (CC with single, double, and triple excitations) models in orders of the Møller-Plesset fluctuation potential. We initially introduce the E-CCSD(T-n) series, in which the CCSD amplitude equations are satisfied at the expansion point, and compare it to the recently developed CCSD(T-n) series [J. J. Eriksen et al., J. Chem. Phys. 140, 064108 (2014)], in which not only the CCSD amplitude, but also the CCSD multiplier equations are satisfied at the expansion point. The computational scaling is similar for the two series, and both are term-wise size extensive with a formal convergence towards the CCSDT target energy. However, the two series are different, and the CCSD(T-n) series is found to exhibit a more rapid convergence up through the series, which we trace back to the fact that more information at the expansion point is utilized than for the E-CCSD(T-n) series. The present analysis can be generalized to any perturbation expansion representing the difference between a parent CC model and a higher-level target CC model. In general, we demonstrate that, whenever the parent parameters depend upon the perturbation operator, a perturbation expansion of the CC energy (where only parent amplitudes are used) differs from a perturbation expansion of the CC Lagrangian (where both parent amplitudes and parent multipliers are used). For the latter case, the bivariational Lagrangian formulation becomes more than a convenient mathematical tool, since it facilitates a different and faster convergent perturbation series than the simpler energy-based expansion.

  13. Regularization and computational methods for precise solution of perturbed orbit transfer problems

    Science.gov (United States)

    Woollands, Robyn Michele

    The author has developed a suite of algorithms for solving the perturbed Lambert's problem in celestial mechanics. These algorithms have been implemented as a parallel computation tool that has broad applicability. This tool is composed of four component algorithms and each provides unique benefits for solving a particular type of orbit transfer problem. The first one utilizes a Keplerian solver (a-iteration) for solving the unperturbed Lambert's problem. This algorithm not only provides a "warm start" for solving the perturbed problem but is also used to identify which of several perturbed solvers is best suited for the job. The second algorithm solves the perturbed Lambert's problem using a variant of the modified Chebyshev-Picard iteration initial value solver that solves two-point boundary value problems. This method converges over about one third of an orbit and does not require a Newton-type shooting method and thus no state transition matrix needs to be computed. The third algorithm makes use of regularization of the differential equations through the Kustaanheimo-Stiefel transformation and extends the domain of convergence over which the modified Chebyshev-Picard iteration two-point boundary value solver will converge, from about one third of an orbit to almost a full orbit. This algorithm also does not require a Newton-type shooting method. The fourth algorithm uses the method of particular solutions and the modified Chebyshev-Picard iteration initial value solver to solve the perturbed two-impulse Lambert problem over multiple revolutions. The method of particular solutions is a shooting method but differs from the Newton-type shooting methods in that it does not require integration of the state transition matrix. The mathematical developments that underlie these four algorithms are derived in the chapters of this dissertation. For each of the algorithms, some orbit transfer test cases are included to provide insight on accuracy and efficiency of these

  14. Iodine-125 thin seeds decrease prostate swelling during transperineal interstitial permanent prostate brachytherapy

    International Nuclear Information System (INIS)

    Beydoun, Nadine; Bucci, Joseph A.; Chin, Yaw S.; Malouf, David

    2014-01-01

    Prostate swelling following seed implantation is a well-recognised phenomenon. The purpose of this intervention was to assess whether using thinner seeds reduces post-implant swelling with permanent prostate brachytherapy. Eighteen consecutive patients eligible for prostate seed brachytherapy underwent seed implantation using iodine-125 (I-125) thin seeds. Operative time, dosimetry, prostate swelling and toxicity were assessed and compared with standard I-125 stranded seed controls, sourced from the department's brachytherapy database. A learning curve was noted with the thin seeds in terms of greater bending and deviation of needles from their intended path. This translated into significantly longer total operative time (88 vs 103 minutes; P=0.009, 95% confidence interval (CI) 4.1-24.3) and time per needle insertion (2.6 vs 3.7 minutes; P<0.001, 95% CI 0.5-1.3) for the thin seeds. Day 30 prostate volumes were significantly smaller in the thin seed group compared with standard seeds (40.9cc vs 46.8cc; P=0.001, 95% CI 1.5-5.6). The ratio of preoperative transrectal ultrasound to day 30 post-implant CT volume was also smaller in the thin seed group (1.2±0.1 for standard seeds vs 1.1±0.1 for thin seeds). Post-implant dosimetric parameters were comparable for both groups. No significant differences were seen in acute urinary morbidity or quality of life between the two groups. I-125 thin seeds are associated with an initial learning curve, with longer operative time, even for experienced brachytherapists. The significant reduction in day 30 prostate volumes with the thin seeds has useful implications in terms of optimising dose coverage to the prostate in the early period post-implantation, as well as improving the accuracy of post-implant dosimetric assessments.

  15. Seed rain, soil seed bank, seed loss and regeneration of Castanopsis fargesii (Fagaceae) in a subtropical evergreen broad-leaved forest

    Science.gov (United States)

    Xiaojun Du; Qinfeng Guo; Xianming Gao; Keping Na

    2007-01-01

    Understanding the seed rain and seed loss dynamics in the natural condition has important significance for revealing the natural regeneration mechanisms.We conducted a 3-year field observation on seed rain, seed loss and natural regeneration of Castanopsis fargesii Franch., a dominant tree species in evergreen broad-leaved forests in Dujiangyan,...

  16. Training and research in seed technology. No quality seeds without skilled staff

    NARCIS (Netherlands)

    Groot, S.P.C.; Hilhorst, H.W.M.

    2016-01-01

    The seed industry in the Netherlands is the largest exporter of horticultural seeds, reaching farmers in every country of the world. High seed quality is one of the key factors of this success. Maintaining and increasing the level of seed qualtiy requires skilled staff, innovation and collaboration

  17. On the non-perturbative effects

    International Nuclear Information System (INIS)

    Manjavidze, J.; Voronyuk, V.

    2004-01-01

    The quantum correspondence principle based on the time reversibility is adopted to take into account the non-Abelian symmetry constrains. The main properties of the new strong-coupling perturbation theory which take into account non-perturbative effects are described. (author)

  18. Chloroxyanion residue on seeds and sprouts after chlorine dioxide sanitation of alfalfa seed

    Science.gov (United States)

    The effects of a 6-h chlorine dioxide sanitation of alfalfa seed (0, 50, 100, and 200 mg/kg seed) on total coliform bacteria, seed germination, and on the presence of chlorate and perchlorate residues in seed rinse, seed soak, and in alfalfa sprouts was determined. Chlorate residues in 20000 ppm cal...

  19. Assessment of Seed Germination and Dormancy of Thirty Seeds Lots of

    Directory of Open Access Journals (Sweden)

    H.R Ehyaee

    2012-06-01

    Full Text Available Most seeds of medicinal plants due to ecological adaptation to environmental conditions have several types of dormancy. Hence, it's necessary to recognize ecological factors that affect dormancy and provide optimum conditions for germination in medicinal plant species. Thirty seed lots were used to estimate germination and dormancy of medicinal plants. Treatments were KNO3, (2% and scarification of seeds by sand paper, hypochlorite sodium and removing the seed coat with four replicates of 25 seeds. Maximum and minimum germination observed in H2O for Digitalis purpure 100% and Saponaria officinalis 0%. In KNO3 treatment, Portulaca oleracea had the highest germination of 91% and Hyocyamus niger had no any germinated seeds. In sand paper treatment, the Saponaria officinalis and Datura stramonium had maximum, 33% and minimum 0% germination respectively.

  20. Comparison of Water Turbidity Removal Efficiencies of Descurainia Sophia Seed Extract and Ferric chloride

    Directory of Open Access Journals (Sweden)

    Mazyar Peyda

    2016-03-01

    Full Text Available Background Turbidity removal using inorganic coagulants such as iron and aluminum salts in water treatment processes causes environmental and human health concern. Historically, the use of natural coagulant to purify turbid water has been practiced for a long time. Recent research indicates that Descurainia Sophia seed can be effectively used as a natural coagulant to remove water turbidity. Method: In this work, turbidity removal efficiency of Descurainia Sophia seed extract was compared with Ferric chloride. Experiments were performed in laboratory scale. The coagulation experiments were done with kaolin as a model soil to produce turbidity in distilled water. The turbidity removal efficiency of Descurainia Sophia seed extract and Ferric chloride were conducted with jar test apparatus. In all experiments, initial turbidity was kept constant 100(NTU. Optimum combination of independent variables was used to compare two different types of coagulants. Result: The obtained results showed that Ferric chloride could remove 89.75% of the initial turbidity, while in case of Descurainia Sophia this value was 43.13%. The total organic carbon (TOC analysis of the treated water using seed extract showed an increased concentration of TOC equal to 0.99 mg/L. Conclusions: This research has shown that Descurainia Sophia seed extract has an acceptable potential in the coagulation/flocculation process to treat turbid water.

  1. Numerical simulation of the regularized long wave equation by He's homotopy perturbation method

    Energy Technology Data Exchange (ETDEWEB)

    Inc, Mustafa [Department of Mathematics, Firat University, 23119 Elazig (Turkey)], E-mail: minc@firat.edu.tr; Ugurlu, Yavuz [Department of Mathematics, Firat University, 23119 Elazig (Turkey)

    2007-09-17

    In this Letter, we present the homotopy perturbation method (shortly HPM) for obtaining the numerical solution of the RLW equation. We obtain the exact and numerical solutions of the Regularized Long Wave (RLW) equation for certain initial condition. The initial approximation can be freely chosen with possible unknown constants which can be determined by imposing the boundary and initial conditions. Comparison of the results with those of other methods have led us to significant consequences. The numerical solutions are compared with the known analytical solutions.

  2. Morphology-controlled synthesis of silver nanostructures via a seed catalysis process

    Science.gov (United States)

    Chen, Chang; Wang, Li; Yu, Haojie; Wang, Jianjun; Zhou, Junfeng; Tan, Qiaohua; Deng, Libo

    2007-03-01

    A novel, effective strategy named 'seed catalysis' has been described here to synthesize silver nanostructures with controllable morphology. Typically, we added Na2S into the reaction system and the Ag2S semiconductor colloids formed at the initial stage would act as both seeds and catalyst in the silver reduction. The morphology of products is controlled by the concentration of Na2S added to the system. Low concentration of Na2S gives nanocubes of 40-50 nm in size, while a high concentration of Na2S is of benefit to obtain nanowires. The growth of the silver crystal is also accelerated by the catalysis of Ag2S. Electron microscopy and UV-vis absorption spectra have been used to investigate the evolution of silver nanowires, and a reasonable mechanism to explain the role of Ag2S seeds has also been suggested. This semiconductor seed catalysis strategy will provide wide applications in the fabrication of metal nanomaterials.

  3. Morphology-controlled synthesis of silver nanostructures via a seed catalysis process

    International Nuclear Information System (INIS)

    Chen Chang; Wang Li; Yu Haojie; Wang Jianjun; Zhou Junfeng; Tan Qiaohua; Deng Libo

    2007-01-01

    A novel, effective strategy named 'seed catalysis' has been described here to synthesize silver nanostructures with controllable morphology. Typically, we added Na 2 S into the reaction system and the Ag 2 S semiconductor colloids formed at the initial stage would act as both seeds and catalyst in the silver reduction. The morphology of products is controlled by the concentration of Na 2 S added to the system. Low concentration of Na 2 S gives nanocubes of 40-50 nm in size, while a high concentration of Na 2 S is of benefit to obtain nanowires. The growth of the silver crystal is also accelerated by the catalysis of Ag 2 S. Electron microscopy and UV-vis absorption spectra have been used to investigate the evolution of silver nanowires, and a reasonable mechanism to explain the role of Ag 2 S seeds has also been suggested. This semiconductor seed catalysis strategy will provide wide applications in the fabrication of metal nanomaterials

  4. Early planting and hand sorting effectively controls seed-borne fungi in farm-retained bean seed

    Directory of Open Access Journals (Sweden)

    Ernest Dube

    2014-11-01

    Full Text Available Home-saved bean (Phaseolus vulgaris L. seed can be hand-sorted to remove discoloured seed, thereby reducing the level of contamination by certain seed-borne fungi and improving seed germination. In this study, the effect of planting date on the infection and discolouration of bean seed by seed-borne fungi was investigated in order to improve the quality of hand-sorted, farm-retained bean seeds used by resource poor smallholder farmers. The germination quality and level of seed-borne fungi in hand-sorted first-generation bean seed harvested from an early-, mid- and late-summer season planted crop was therefore assessed. The highest percentage of discoloured seed (68% was obtained from the mid-summer season planting. Non-discoloured seed from early- and late-season plantings had significantly (p"less than"0.001 higher normal germination (82% and 77%, respectively than that from the mid-season planting date (58%. Irrespective of planting date, unsorted seed and discoloured seed had higher levels of infection by Fusarium spp. and Phaeoisariopsis spp. than the non-discoloured seed. Removal of discoloured seed by hand sorting eliminated Rhizoctonia spp. from all seed lots. Farmers can eliminate this pathogen by simply removing discoloured seed. Non-discoloured seed from the early-planted crop had the lowest level of infection by Fusarium spp. and Phaeoisariopsis spp. The results indicate that planting date is an important consideration in improving the quality of hand-sorted farm-retained bean seed.

  5. Primordial black holes as seeds of magnetic fields in the universe

    Science.gov (United States)

    Safarzadeh, Mohammadtaher

    2018-06-01

    Although it is assumed that magnetic fields in accretion disks are dragged from the interstellar medium, the idea is likely not applicable to primordial black holes (PBHs) formed in the early universe. Here we show that magnetic fields can be generated in initially unmagnetized accretion disks around PBHs through the Biermann battery mechanism, and therefore provide the small scale seeds of magnetic field in the universe. The radial temperature and vertical density profiles of these disks provide the necessary conditions for the battery to operate naturally. The generated seed fields have a toroidal structure with opposite sign in the upper and lower half of the disk. In the case of a thin accretion disk around a rotating PBH, the field generation rate increases with increasing PBH spin. At a fixed r/risco, where r is the radial distance from the PBH and risco is the radius of the innermost stable circular orbit, the battery scales as M-9/4, where M is the PBH's mass. The very weak dependency of the battery on accretion rate, makes this mechanism a viable candidate to provide seed fields in an initially unmagnetized accretion disk, following which the magnetorotational instability could take over.

  6. Comparisons between two economically valuable forest species (Eucalyptus grandis and Pinus taeda in relation to seed behaviour under controlled deterioration

    Directory of Open Access Journals (Sweden)

    Jussara Bertho Fantinatti

    2011-02-01

    Full Text Available The objectives of this work were to analyze seed behaviour under controlled deterioration and estimate viability equations for forest species Eucalyptus grandis and Pinus taeda. Desired moisture content levels were achieved from initial values after either rehydration over water or drying over silica gel, both at 25 ºC. Seed sub samples with 8 moisture contents each for E. grandis (1.2 to 18.1%, initial value of 11.3% and P. taeda (1.5 to 19.5%, initial value of 12.9% were sealed in laminate aluminium-foil packets and stored in incubators maintained at 40, 50 and 65 ºC. The seeds from these species exhibited true orthodox and sub-orthodox storage behaviour, respectively, however E. grandis showed higher seed storability, probably due to a different seed chemical composition. Lowest moisture content limits estimated for application of the viability equations at 65 ºC were 4.9 and 4.1 mc for E. grandis and P. taeda, on equilibrium with ±20% RH. The viability equation estimated quantified the response of seed longevity to storage environment well with K E = 9.661 and 8.838; C W = 6.467 and 5.981; C H = 0.03498 and 0.10340; C Q = 0.0002330 and 0.0005476, for E. grandis and P. taeda, respectively.

  7. Evolution of the curvature perturbations during warm inflation

    International Nuclear Information System (INIS)

    Matsuda, Tomohiro

    2009-01-01

    This paper considers warm inflation as an interesting application of multi-field inflation. Delta-N formalism is used for the calculation of the evolution of the curvature perturbations during warm inflation. Although the perturbations considered in this paper are decaying after the horizon exit, the corrections to the curvature perturbations sourced by these perturbations can remain and dominate the curvature perturbations at large scales. In addition to the typical evolution of the curvature perturbations, inhomogeneous diffusion rate is considered for warm inflation, which may lead to significant non-Gaussianity of the spectrum

  8. Effects of boarding return satellite on antioxidant enzyme activities during germination of hot pepper seed

    International Nuclear Information System (INIS)

    Li Shuifeng; Wang Bingliang; Guan Xueyu; Zhang Yan

    2006-01-01

    The effect of boarding return satellite on antioxidant enzyme activities during germination of hot pepper seed was studied. The results showed that the germination potentiality and germination rate of hot pepper seed after boarding return satellite were increased by 3.5% and 5.3%, respectively. During seed germination, soluble protein and MDA contents decreased, however, the SOD activities increased. SOD activity of treated seeds was higher than that of the control especially during the initial period of germination, while the content of soluble and MDA contents were much lower than those of control. The activities of SOD, G-POD, APX and CAT in 13d seedlings of treated seeds were increased by 14.29%, 25.23%, 1.84% and 21.52%, respectively. It was concluded that space flight enhanced antioxidant enzyme activities of seeds and seedlings, which were very important to prevent membrane lipid superoxide. (authors)

  9. Perturbative spacetimes from Yang-Mills theory

    Energy Technology Data Exchange (ETDEWEB)

    Luna, Andrés [School of Physics and Astronomy, University of Glasgow,Glasgow G12 8QQ, Scotland (United Kingdom); Monteiro, Ricardo [Theoretical Physics Department, CERN,Geneva (Switzerland); Nicholson, Isobel; Ochirov, Alexander; O’Connell, Donal [Higgs Centre for Theoretical Physics,School of Physics and Astronomy, The University of Edinburgh,Edinburgh EH9 3JZ, Scotland (United Kingdom); Westerberg, Niclas [Institute of Photonics and Quantum Sciences,School of Engineering and Physical Sciences, Heriot-Watt University,Edinburgh (United Kingdom); Higgs Centre for Theoretical Physics,School of Physics and Astronomy, The University of Edinburgh,Edinburgh EH9 3JZ, Scotland (United Kingdom); White, Chris D. [Centre for Research in String Theory,School of Physics and Astronomy, Queen Mary University of London,327 Mile End Road, London E1 4NS (United Kingdom)

    2017-04-12

    The double copy relates scattering amplitudes in gauge and gravity theories. In this paper, we expand the scope of the double copy to construct spacetime metrics through a systematic perturbative expansion. The perturbative procedure is based on direct calculation in Yang-Mills theory, followed by squaring the numerator of certain perturbative diagrams as specified by the double-copy algorithm. The simplest spherically symmetric, stationary spacetime from the point of view of this procedure is a particular member of the Janis-Newman-Winicour family of naked singularities. Our work paves the way for applications of the double copy to physically interesting problems such as perturbative black-hole scattering.

  10. Responses of seed germination, seedling growth, and seed yield traits to seed pretreatment in maize (Zea mays L.).

    Science.gov (United States)

    Tian, Yu; Guan, Bo; Zhou, Daowei; Yu, Junbao; Li, Guangdi; Lou, Yujie

    2014-01-01

    A series of seed priming experiments were conducted to test the effects of different pretreatment methods to seed germination, seedling growth, and seed yield traits in maize (Zea mays L.). Results indicated that the seeds primed by gibberellins (GA), NaCl, and polyethylene glycol (PEG) reagents showed a higher imbibitions rate compared to those primed with water. The final germination percentage and germination rate varied with different reagents significantly (P germination experiment. 15% PEG priming reagent increased shoot and root biomass of maize seedling. The shoot biomass of seedlings after presoaking the seeds with NaCl reagent was significantly higher than the seedlings without priming treatment. No significant differences of plant height, leaf number, and hundred-grain weight were observed between control group and priming treatments. Presoaking with water, NaCl (50 mM), or PEG (15%) significantly increased the hundred-grain weight of maize. Therefore, seed pretreatment is proved to be an effective technique to improve the germination performance, seedling growth, and seed yield of maize. However, when compared with the two methods, if immediate sowing is possible, presoaking is recommended to harvest better benefits compared to priming method.

  11. Nonperturbative perturbation theory

    International Nuclear Information System (INIS)

    Bender, C.M.

    1989-01-01

    In this talk we describe a recently proposed graphical perturbative calculational scheme for quantum field theory. The basic idea is to expand in the power of the interaction term. For example, to solve a λφ 4 theory in d-dimensional space-time, we introduce a small parameter δ and consider a λ(φ 2 ) 1+δ field theory. We show how to expand such a theory as a series in powers of δ. The resulting perturbation series appears to have a finite radius of convergence and numerical results for low-dimensional models are good. We have computed the two-point and four-point Green's functions to second order in powers of δ and the 2n-point Green's functions (n>2) to order δ. We explain how to renormalize the theory and show that, to first order in powers of δ, when δ>0 and d≥4 the theory is free. This conclusion remains valid to second order in powers of δ, and we believe that it remains valid to all orders in powers of δ. The new perturbative scheme is consistent with global supersymmetry invariance. We examine a two-dimensional supersymmetric quantum field theory in which we do not know of any other means for doing analytical calculations. We illustrate the power of this new technique by computing the ground-state energy density E to second order in this new perturbation theory. We show that there is a beautiful and delicate cancellation between infinite classes of graphs which leads to the result that E=0. (orig.)

  12. Spinach seed quality - potential for combining seed size grading and chlorophyll flourescence sorting

    DEFF Research Database (Denmark)

    Deleuran, Lise Christina; Olesen, Merete Halkjær; Boelt, Birte

    2013-01-01

    might therefore improve the establishment of spinach for producers. Spinach seeds were harvested at five different times (H1, H2, H3, H4 and H5) starting 3 weeks before estimated optimum harvest time. The harvested seeds were sorted according to chlorophyll fluorescence (CF) and seed size. Two harvest.......5–3.25 mm size seeds had germinated on day 3 than both their larger and smaller counterparts at the later time of harvest (H4). Seeds with a diameter below 2.5 mm displayed the lowest MGT. Commercially, the use of chlorophyll fluorescence (CF)-sorted seeds, in combination with seed size sorting, may provide...

  13. [Effects of illumination and seed-soaking reagent on seed germination of Solanum nigrum].

    Science.gov (United States)

    Yang, Chuan-Jie; Wei, Shu-He; Zhou, Qi-Xing; Hu, Ya-Hu; Niu, Rong-Cheng

    2009-05-01

    To explore a rapid seed germination method for hyperaccumulator Solanum nigrum, a germination experiment with different illumination and seed-soaking treatments was conducted in constant temperature box and greenhouse, with filter as burgeon base. Under illumination, the germination rate was about 5 times high of that without illumination (P seed germination of S. nigrum. All test seed-soaking reagents could significantly improve the germination rate of S. nigrum (P seeds treated with H2O2 had the shortest germination time. The germination rate of seeds soaked but without cleaning was 2-3 times as high as that of seeds soaked and cleaned with water.

  14. Introduction to non-perturbative quantum chromodynamics

    International Nuclear Information System (INIS)

    Pene, O.

    1995-01-01

    Quantum chromodynamics is considered to be the theory of strong interaction. The main peculiarity of this theory is that its asymptotic states (hadrons) are different from its elementary fields (quarks and gluons). This property plays a great part in any physical process involving small momentum-energy transfers. In such a range perturbative methods are no longer allowed. This work focuses on other tools such as QCD symmetry, the quark model, Green functions and the sum rules. To get hadron characteristics numerically, QCD on lattices is used but only in the case of simple process involving no more than one hadron in the initial and final states because of the complexity of the Green function. Some examples using a Monte-Carlo simulation are given. (A.C.)

  15. Polymorphism of amyloid-like fibrils can be defined by the concentration of seeds

    Directory of Open Access Journals (Sweden)

    Tomas Sneideris

    2015-08-01

    Full Text Available Prions are infectious proteins where the same protein may express distinct strains. The strains are enciphered by different misfolded conformations. Strain-like phenomena have also been reported in a number of other amyloid-forming proteins. One of the features of amyloid strains is the ability to self-propagate, maintaining a constant set of physical properties despite being propagated under conditions different from those that allowed initial formation of the strain. Here we report a cross-seeding experiment using strains formed under different conditions. Using high concentrations of seeds results in rapid elongation and new fibrils preserve the properties of the seeding fibrils. At low seed concentrations, secondary nucleation plays the major role and new fibrils gain properties predicted by the environment rather than the structure of the seeds. Our findings could explain conformational switching between amyloid strains observed in a wide variety of in vivo and in vitro experiments.

  16. Increasing seed size and quality by manipulating BIG SEEDS1 in legume species.

    Science.gov (United States)

    Ge, Liangfa; Yu, Jianbin; Wang, Hongliang; Luth, Diane; Bai, Guihua; Wang, Kan; Chen, Rujin

    2016-11-01

    Plant organs, such as seeds, are primary sources of food for both humans and animals. Seed size is one of the major agronomic traits that have been selected in crop plants during their domestication. Legume seeds are a major source of dietary proteins and oils. Here, we report a conserved role for the BIG SEEDS1 (BS1) gene in the control of seed size and weight in the model legume Medicago truncatula and the grain legume soybean (Glycine max). BS1 encodes a plant-specific transcription regulator and plays a key role in the control of the size of plant organs, including seeds, seed pods, and leaves, through a regulatory module that targets primary cell proliferation. Importantly, down-regulation of BS1 orthologs in soybean by an artificial microRNA significantly increased soybean seed size, weight, and amino acid content. Our results provide a strategy for the increase in yield and seed quality in legumes.

  17. Critical seeding density improves properties and translatability of self-assembling anatomically shaped knee menisci

    Science.gov (United States)

    Hadidi, Pasha; Yeh, Timothy C.; Hu, Jerry C.; Athanasiou, Kyriacos A.

    2014-01-01

    A recent development in the field of tissue engineering is the rise of all-biologic, scaffold-free engineered tissues. Since these biomaterials rely primarily upon cells, investigation of initial seeding densities constitutes a particularly relevant aim for tissue engineers. In this study, a scaffold-free method was used to create fibrocartilage in the shape of the rabbit knee meniscus. The objectives of this study were: (i) to determine the minimum seeding density, normalized by an area of 44 mm2, necessary for the self-assembling process of fibrocartilage to occur, (ii) examine relevant biomechanical properties of engineered fibrocartilage, such as tensile and compressive stiffness and strength, and their relationship to seeding density, and (iii) identify a reduced, or optimal, number of cells needed to produce this biomaterial. It was found that a decreased initial seeding density, normalized by the area of the construct, produced superior mechanical and biochemical properties. Collagen per wet weight, glycosaminoglycans per wet weight, tensile properties, and compressive properties were all significantly greater in the 5 million cells per construct group as compared to the historical 20 million cells per construct group. Scanning electron microscopy demonstrated that a lower seeding density results in a denser tissue. Additionally, the translational potential of the self-assembling process for tissue engineering was improved though this investigation, as fewer cells may be used in the future. The results of this study underscore the potential for critical seeding densities to be investigated when researching scaffold-free engineered tissues. PMID:25234157

  18. Conference Proceedings: Seed Ecology III - The Third International Society for Seed Science Meeting on Seeds and the Environment - "Seeds and Change"; June 20-June 24, 2010; Salt Lake City, Utah, USA

    Science.gov (United States)

    Rosemary Pendleton; Susan Meyer; Bitsy Schultz

    2010-01-01

    Seed Ecology III was held in Salt Lake City, Utah in June 2010, sharing the latest research on all aspects of seed ecology. Our meeting was organized around the theme "Seeds and Change." We welcomed contributions in any area of seed ecology. Our agenda also aimed to create bridges between seed ecology and plant conservation, restoration ecology, and global...

  19. How seed orchard culture affects seed quality: experience with the southern pines

    Science.gov (United States)

    James P. Barnett

    1996-01-01

    Tree improvement programs have influenced significantly the quality of southern pine seeds produced when compared to collections from native stands. Seed orchard management practices such as fertilization can increase seed size and reduce seed dormancy. These result in the need for less complex pregermination treatments. Repeated cone collections from the same clones...

  20. Paper (essay on seed

    Directory of Open Access Journals (Sweden)

    Mirić Mladen

    2013-01-01

    Full Text Available Based on detailed studies of the past of the agrarian thought of the world (evolution of agro-innovation, and within it, the relationship of man and seed, the author has selected key data for Table 1. In addition, more or less known folk sayings, proverbs, curses and allegories in which the seed is the key word have been collected. Then, religious books, folk art and literature works (sayings of prominent individuals and experts and observations of the author himself have been studied. According to the collected opus, it can be concluded that the vast importance of seed meaningfully entwined into all spheres of folk life and cultural heritage. Seed is directly tied to the following eight key (revolutionary milestones in the food and economic life of mankind: 1. the first and for the longest time, the seed used to be the main food of the people and the first food reserve; 2. Neolithic Revolution was simply caused by the sowing of seeds; 3. for the sake of sowing man began to develop more complex processing techniques; 4. everywhere and forever, especially since the late 15th century, the seed has been a carrier of (rescuing plants between Europe and the New World, that is, between continents; 5. seed was the first product that has been chemically treated since the mid-18th century; 6. standard operation procedures and quality are promoted on seed by which it became the first product to have prescribed (compulsory methods, but it also became a good whose quality has to be tested before sale; 7. hybrid seed is a 'perpetrator' of the green revolution in the mid-20th century and at last there is disputable seed of genetically modified organisms that are spreading with certain reactions. The author proposes that the United Nations Standard International Trade Classification includes a special section (division which would classify the seed for sowing, while beyond this Classification terms such as seed, plant seed should be replaced with non-seed

  1. Factors influencing upon the incidence of seed migration in I-125 seed transperineal prostate implantation

    International Nuclear Information System (INIS)

    Itami, Jun; Onishi, Kayoko; Kanemura, Mikio

    2005-01-01

    Transperineal I-125 seed brachytherapy for prostate cancer is rapidly expanding in Japan. Seed migrations to lung and abdomen are well known complication in the seed brachytherapy. The rate of incidence and the predisposing factors were studied. From April 2004 through January 2005, 36 patients underwent transperineal I-125 seed brachytherapy for prostate cancer. In all patients loose I-125 seeds were inserted with Mick applicator according to modified peripheral loading pattern. One day, 1 week, and 1 month after the procedure, posteroanterior and lateral chest X-rays and abdominal X-ray were performed. Abdominal and chest seed migrations were seen in 11 (30.6%) and 14 (38.9%) patients, respectively. In total, 20 patients (55.6%) showed seed migrations. Forty-two I-125 seeds migrated out of 2,508 implanted seeds. Most of the migrations were seen until 1 month after the procedure. The preplanned number of the extraprostatic seeds had a statistically significant influence upon the incidence of seed migration. Seed migration is not a rare phenomenon in transperineal I-125 seed brachytherapy for prostate cancer. To confirm seed migration, X-ray examinations 1 month after the procedure are suited. At the preplanning, the number of extraprostatic seeds should be limited to minimal to decrease the incidence of seed migration. In future, the introduction of linked I-125 seeds is preferred. (author)

  2. A new Method for the Estimation of Initial Condition Uncertainty Structures in Mesoscale Models

    Science.gov (United States)

    Keller, J. D.; Bach, L.; Hense, A.

    2012-12-01

    The estimation of fast growing error modes of a system is a key interest of ensemble data assimilation when assessing uncertainty in initial conditions. Over the last two decades three methods (and variations of these methods) have evolved for global numerical weather prediction models: ensemble Kalman filter, singular vectors and breeding of growing modes (or now ensemble transform). While the former incorporates a priori model error information and observation error estimates to determine ensemble initial conditions, the latter two techniques directly address the error structures associated with Lyapunov vectors. However, in global models these structures are mainly associated with transient global wave patterns. When assessing initial condition uncertainty in mesoscale limited area models, several problems regarding the aforementioned techniques arise: (a) additional sources of uncertainty on the smaller scales contribute to the error and (b) error structures from the global scale may quickly move through the model domain (depending on the size of the domain). To address the latter problem, perturbation structures from global models are often included in the mesoscale predictions as perturbed boundary conditions. However, the initial perturbations (when used) are often generated with a variant of an ensemble Kalman filter which does not necessarily focus on the large scale error patterns. In the framework of the European regional reanalysis project of the Hans-Ertel-Center for Weather Research we use a mesoscale model with an implemented nudging data assimilation scheme which does not support ensemble data assimilation at all. In preparation of an ensemble-based regional reanalysis and for the estimation of three-dimensional atmospheric covariance structures, we implemented a new method for the assessment of fast growing error modes for mesoscale limited area models. The so-called self-breeding is development based on the breeding of growing modes technique

  3. Alleviate Seed Ageing Effects in Silybum marianum by Application of Hormone Seed Priming

    Directory of Open Access Journals (Sweden)

    Seyed Ata SIADAT

    2015-09-01

    Full Text Available Most of the medicinal plants have seed dormancy or poor seed germination. This is due to their natural compounds or their morphological structure. Existence of such mechanisms makes the seeds able to endure harsh environments, stressful conditions or natural ageing. Different seed enhancement treatments were proposed in order to improve seed germination. In this study, it was examined Silybum marianum seed longevity (0, 48 and 72 hour of ageing and the response to seed priming when using different concentrations of cytokinin (50, 200, 350 and 500 ppm and different duration of treatment (8, 12 and 24 hour. Results revealed that ageing could be successfully alleviated using seed priming. Seed ageing significantly affected seed germination and vigour. Application of cytokinin considerably improved seed vigour in aged and non aged seeds. The most effective seed priming treatment was with 500 ppm cytokine, with the duration of 24 hours. In conclusion, it can be recommend the used of plant growth regulators like cytokine, as a good priming agent, to recover losses of seed quality and improve germination characteristics.

  4. Agricultural robot designed for seeding mechanism

    Science.gov (United States)

    Sunitha, K. A., Dr.; Suraj, G. S. G. S.; Sowrya, CH P. N.; Atchyut Sriram, G.; Shreyas, D.; Srinivas, T.

    2017-05-01

    In the field of agriculture, plantation begins with ploughing the land and sowing seeds. The old traditional method plough attached to an OX and tractors needs human involvement to carry the process. The driving force behind this work is to reduce the human interference in the field of agriculture and to make it cost effective. In this work, apart of the land is taken into consideration and the robot introduced localizes the path and can navigate itself without human action. For ploughing, this robot is provided with tentacles attached with saw blades. The sowing mechanism initiates with long toothed gears actuated with motors. The complete body is divided into two parts the tail part acts as a container for seeds. The successor holds on all the electronics used for automating and actuation. The locomotion is provided with wheels covered under conveyor belts. Gears at the back of the robot rotate in equal speed with respect to each other with the saw blades. For each rotation every tooth on gear will take seeds and will drop them on field. Camera at the front end tracks the path for every fixed distance and at the minimum distance it takes the path pre-programmed.

  5. Fast spectral source integration in black hole perturbation calculations

    Science.gov (United States)

    Hopper, Seth; Forseth, Erik; Osburn, Thomas; Evans, Charles R.

    2015-08-01

    This paper presents a new technique for achieving spectral accuracy and fast computational performance in a class of black hole perturbation and gravitational self-force calculations involving extreme mass ratios and generic orbits. Called spectral source integration (SSI), this method should see widespread future use in problems that entail (i) a point-particle description of the small compact object, (ii) frequency domain decomposition, and (iii) the use of the background eccentric geodesic motion. Frequency domain approaches are widely used in both perturbation theory flux-balance calculations and in local gravitational self-force calculations. Recent self-force calculations in Lorenz gauge, using the frequency domain and method of extended homogeneous solutions, have been able to accurately reach eccentricities as high as e ≃0.7 . We show here SSI successfully applied to Lorenz gauge. In a double precision Lorenz gauge code, SSI enhances the accuracy of results and makes a factor of 3 improvement in the overall speed. The primary initial application of SSI—for us its the raison d'être—is in an arbitrary precision mathematica code that computes perturbations of eccentric orbits in the Regge-Wheeler gauge to extraordinarily high accuracy (e.g., 200 decimal places). These high-accuracy eccentric orbit calculations would not be possible without the exponential convergence of SSI. We believe the method will extend to work for inspirals on Kerr and will be the subject of a later publication. SSI borrows concepts from discrete-time signal processing and is used to calculate the mode normalization coefficients in perturbation theory via sums over modest numbers of points around an orbit. A variant of the idea is used to obtain spectral accuracy in a solution of the geodesic orbital motion.

  6. Kerr-CFT and gravitational perturbations

    International Nuclear Information System (INIS)

    Dias, Oscar J.C.; Reall, Harvey S.; Santos, Jorge E.

    2009-01-01

    Motivated by the Kerr-CFT conjecture, we investigate perturbations of the near-horizon extreme Kerr spacetime. The Teukolsky equation for a massless field of arbitrary spin is solved. Solutions fall into two classes: normal modes and traveling waves. Imposing suitable (outgoing) boundary conditions, we find that there are no unstable modes. The explicit form of metric perturbations is obtained using the Hertz potential formalism, and compared with the Kerr-CFT boundary conditions. The energy and angular momentum associated with scalar field and gravitational normal modes are calculated. The energy is positive in all cases. The behaviour of second order perturbations is discussed.

  7. The power of perturbation theory

    Energy Technology Data Exchange (ETDEWEB)

    Serone, Marco [SISSA International School for Advanced Studies and INFN Trieste, Via Bonomea 265, 34136, Trieste (Italy); Abdus Salam International Centre for Theoretical Physics, Strada Costiera 11, 34151, Trieste (Italy); Spada, Gabriele [SISSA International School for Advanced Studies and INFN Trieste, Via Bonomea 265, 34136, Trieste (Italy); Villadoro, Giovanni [Abdus Salam International Centre for Theoretical Physics, Strada Costiera 11, 34151, Trieste (Italy)

    2017-05-10

    We study quantum mechanical systems with a discrete spectrum. We show that the asymptotic series associated to certain paths of steepest-descent (Lefschetz thimbles) are Borel resummable to the full result. Using a geometrical approach based on the Picard-Lefschetz theory we characterize the conditions under which perturbative expansions lead to exact results. Even when such conditions are not met, we explain how to define a different perturbative expansion that reproduces the full answer without the need of transseries, i.e. non-perturbative effects, such as real (or complex) instantons. Applications to several quantum mechanical systems are presented.

  8. Analyzing the Response of Climate Perturbations to (Tropical) Cyclones using the WRF Model

    Science.gov (United States)

    Tewari, M.; Mittal, R.; Radhakrishnan, C.; Cipriani, J.; Watson, C.

    2015-12-01

    An analysis of global climate models shows considerable changes in the intensity and characteristics of future, warm climate cyclones. At regional scales, deviations in cyclone characteristics are often derived using idealized perturbations in the humidity, temperature and surface conditions. In this work, a more realistic approach is adopted by applying climate perturbations from the Community Climate System Model (CCSM4) to ERA-interim data to generate the initial and boundary conditions for future climate simulations. The climate signal perturbations are generated from the differences in 21 years of mean data from CCSM4 with representative concentration pathways (RCP8.5) for the periods: (a) 2070-2090 (future climate), (b) 2025-2045 (near-future climate) and (c) 1985-2005 (current climate). Four individual cyclone cases are simulated with and without climate perturbations using the Weather Research and Forecasting model with a nested configuration. Each cyclone is characterized by variations in intensity, landfall location, precipitation and societal damage. To calculate societal damage, we use the recently introduced Cyclone Damage Potential (CDP) index evolved from the Willis Hurricane Index (WHI). As CDP has been developed for general societal applications, this work should provide useful insights for resilience analyses and industry (e.g., re-insurance).

  9. A complete basis for a perturbation expansion of the general N-body problem

    International Nuclear Information System (INIS)

    Laing, W Blake; Kelle, David W; Dunn, Martin; Watson, Deborah K

    2009-01-01

    We discuss a basis set developed to calculate perturbation coefficients in an expansion of the general N-body problem. This basis has two advantages. First, the basis is complete order-by-order for the perturbation series. Second, the number of independent basis tensors spanning the space for a given order does not scale with N, the number of particles, despite the generality of the problem. At first order, the number of basis tensors is 25 for all N, i.e. the problem scales as N 0 , although one would initially expect an N 6 scaling at first order. The perturbation series is expanded in inverse powers of the spatial dimension. This results in a maximally symmetric configuration at lowest order which has a point group isomorphic with the symmetric group, S N . The resulting perturbation series is order-by-order invariant under the N! operations of the S N point group which is responsible for the slower than exponential growth of the basis. In this paper, we demonstrate the completeness of the basis and perform the first test of this formalism through first order by comparing to an exactly solvable fully interacting problem of N particles with a two-body harmonic interaction potential

  10. Effects of seed collecting date and storage duration on seed ...

    African Journals Online (AJOL)

    The objective of this study was to determine the effect of seed collecting dates (5 to 6 times from mid-November to early January, 10 days intervals) and seed storage duration (4, 8, and 12 months) at room temperature on seed germination of four Artemisia species (Artemisia sieberi, A. diffusa, A. kupetdaghensis, and A.

  11. Enhanced Coagulation Efficiency of Moringa Oleifera Seeds Through Selective Oil Extraction

    Directory of Open Access Journals (Sweden)

    Suleyman A. Muyibi

    2012-10-01

    Full Text Available In this laboratory based study, varying quantities of oil, corresponding to 20 % w/w, 25 % w/w and 30 % w/w kernel weight extracted from Moringa oleifera seeds ( S1, S2, S3 respectively  were applied in the coagulation of model turbid water (kaolin suspension and turbid river water samples from River Batang Kali and River Selangor in Malaysia to determine the percentage oil removed which gave the best coagulation efficiency. For model turbid water (kaolin suspension coagulation of low turbidity of 35 NTU, medium turbidity of 100 NTU and high turbidity of 300 NTU, sample S2  gave the best turbidity removal corresponding to 91.7%, 95.5% and 99% respectively. Application of sample S2 to River Batang Kali with low initial turbidity of 32 NTU and high initial turbidity of 502 NTU gave a highest turbidity removal of 69% and 99% respectively. Application to River Selangor with medium initial turbidity- of 87 NTU and high initial turbidity of 466 NTU gave a highest residual turbidity' of 94% and 98.9%,  respectively.Key words: Moringa oleifera seed, selective oil extraction, coagulation, model turbid water (kaolin suspension, river water, turbidity removal.

  12. Non linear interaction between a Langmuir wave and a ballistic perturbation

    International Nuclear Information System (INIS)

    Gervais, F.; Olivain, J.; Quemeneur, A.; Trocheris, M.

    1979-05-01

    The theoretical solutions of the Landau-Vlasov initial value problem giving mode-mode coupling usually neglect the free-streaming contribution. We solve theoretically this problem including the ballistic terms. We find that a new mode appears resulting from the nonlinear interaction between the Landau component and the ballistic perturbation. The amplitude of this mode is calculated as a function of distance and compared with experimental results in a plasma column

  13. Mono-implicit Runge Kutta schemes for singularly perturbed delay differential equations

    Science.gov (United States)

    Rihan, Fathalla A.; Al-Salti, Nasser S.

    2017-09-01

    In this paper, we adapt Mono-Implicit Runge-Kutta schemes for numerical approximations of singularly perturbed delay differential equations. The schemes are developed to reduce the computational cost of the fully implicit method which combine the accuracy of implicit method and efficient implementation. Numerical stability properties of the schemes are investigated. Numerical simulations are provided to show the effectiveness of the method for both stiff and non-stiff initial value problems.

  14. Influence of pump power and modulation instability gain spectrum on seeded supercontinuum and rogue wave generation

    DEFF Research Database (Denmark)

    Sørensen, Simon Toft; Larsen, Casper; Møller, Uffe

    2012-01-01

    The noise properties of a supercontiuum can be significantly improved both in terms of coherence and intensity stability by modulating the input pulse with a seed. In this paper, we numerically investigate the influence of the seed wavelength, the pump power, and the modulation instability gain...... spectrum on the seeding process. The results can be clearly divided into a number of distinct dynamical regimes depending on the initial four-wave mixing process. We further demonstrate that seeding can be used to generate coherent and incoherent rogue waves, depending on the modulation instability gain...... spectrum. Finally, we show that the coherent pulse breakup afforded by seeding is washed out by turbulent solitonic dynamics when the pump power is increased to the kilowatt level. Thus our results show that seeding cannot improve the noise performance of a high power supercontinuum source....

  15. Proanthocyanidins in seed coat tegmen and endospermic cap inhibit seed germination in Sapium sebiferum.

    Science.gov (United States)

    Shah, Faheem Afzal; Ni, Jun; Chen, Jing; Wang, Qiaojian; Liu, Wenbo; Chen, Xue; Tang, Caiguo; Fu, Songling; Wu, Lifang

    2018-01-01

    Sapium sebiferum , an ornamental and bio-energetic plant, is propagated by seed. Its seed coat contains germination inhibitors and takes a long time to stratify for germination. In this study, we discovered that the S. sebiferum seed coat (especially the tegmen) and endospermic cap (ESC) contained high levels of proanthocyanidins (PAs). Seed coat and ESC removal induced seed germination, whereas exogenous application with seed coat extract (SCE) or PAs significantly inhibited this process, suggesting that PAs in the seed coat played a major role in regulating seed germination in S. sebiferum . We further investigated how SCE affected the expression of the seed-germination-related genes. The results showed that treatment with SCE upregulated the transcription level of the dormancy-related gene, gibberellins (GAs) suppressing genes, abscisic acid (ABA) biosynthesis and signalling genes. SCE decreased the transcript levels of ABA catabolic genes, GAs biosynthesis genes, reactive oxygen species genes and nitrates-signalling genes. Exogenous application of nordihydroguaiaretic acid, gibberellic acid, hydrogen peroxide and potassium nitrate recovered seed germination in seed-coat-extract supplemented medium. In this study, we highlighted the role of PAs, and their interactions with the other germination regulators, in the regulation of seed dormancy in S. sebiferum .

  16. Non-adiabatic perturbations in multi-component perfect fluids

    Energy Technology Data Exchange (ETDEWEB)

    Koshelev, N.A., E-mail: koshna71@inbox.ru [Ulyanovsk State University, Leo Tolstoy str 42, 432970 (Russian Federation)

    2011-04-01

    The evolution of non-adiabatic perturbations in models with multiple coupled perfect fluids with non-adiabatic sound speed is considered. Instead of splitting the entropy perturbation into relative and intrinsic parts, we introduce a set of symmetric quantities, which also govern the non-adiabatic pressure perturbation in models with energy transfer. We write the gauge invariant equations for the variables that determine on a large scale the non-adiabatic pressure perturbation and the rate of changes of the comoving curvature perturbation. The analysis of evolution of the non-adiabatic pressure perturbation has been made for several particular models.

  17. Non-adiabatic perturbations in multi-component perfect fluids

    International Nuclear Information System (INIS)

    Koshelev, N.A.

    2011-01-01

    The evolution of non-adiabatic perturbations in models with multiple coupled perfect fluids with non-adiabatic sound speed is considered. Instead of splitting the entropy perturbation into relative and intrinsic parts, we introduce a set of symmetric quantities, which also govern the non-adiabatic pressure perturbation in models with energy transfer. We write the gauge invariant equations for the variables that determine on a large scale the non-adiabatic pressure perturbation and the rate of changes of the comoving curvature perturbation. The analysis of evolution of the non-adiabatic pressure perturbation has been made for several particular models

  18. Proteomic analysis of the seed development in Jatropha curcas: from carbon flux to the lipid accumulation.

    Science.gov (United States)

    Liu, Hui; Wang, Cuiping; Komatsu, Setsuko; He, Mingxia; Liu, Gongshe; Shen, Shihua

    2013-10-08

    To characterize the metabolic signatures of lipid accumulation in Jatropha curcas seeds, comparative proteomic technique was employed to profile protein changes during the seed development. Temporal changes in comparative proteome were examined using gels-based proteomic technique at six developmental stages for lipid accumulation. And 104 differentially expressed proteins were identified by MALDI-TOF/TOF tandem mass spectrometry. These protein species were classified into 10 functional categories, and the results demonstrated that protein species related to energy and metabolism were notably accumulated and involved in the carbon flux to lipid accumulation that occurs primarily from early to late stage in seed development. Glycolysis and oxidative pentose phosphate pathways were the major pathways of producing carbon flux, and the glucose-6-phosphate and triose-phosphate are the major carbon source for fatty acid synthesis. Lipid analysis revealed that fatty acid accumulation initiated 25days after flowering at the late stage of seed development of J. curcas. Furthermore, C16:0 was initially synthesized as the precursor for the elongation to C18:1 and C18:2 in the developing seeds of J. curcas. Together, the metabolic signatures on protein changes in seed development provide profound knowledge and perspective insights into understanding lipid network in J. curcas. Due to the abundant oil content in seeds, Jatropha curcas seeds are being considered as the ideal materials for biodiesel. Although several studies had carried out the transcriptomic project to study the genes expression profiles in seed development of J. curcas, these ESTs hadn't been confirmed by qRT-PCR. Yet, the seed development of J. curcas had been described for a pool of developing seeds instead of being characterized systematically. Moreover, cellular metabolic events are also controlled by protein-protein interactions, posttranslational protein modifications, and enzymatic activities which

  19. Seed-specific overexpression of AtFAX1 increases seed oil content in Arabidopsis.

    Science.gov (United States)

    Tian, Yinshuai; Lv, Xueyan; Xie, Guilan; Zhang, Jing; Xu, Ying; Chen, Fang

    2018-06-02

    Biosynthesis of plant seed oil is accomplished through the coordinate action of multiple enzymes in multiple subcellular compartments. Fatty acid (FA) has to be transported from plastid to endoplasmic reticulum (ER) for TAG synthesis. However, the role of plastid FA transportation during seed oil accumulation has not been evaluated. AtFAX1 (Arabidopsis fatty acid export1) mediated the FA export from plastid. In this study, we overexpressed AtFAX1 under the control of a seed specific promoter in Arabidopsis. The resultant overexpression lines (OEs) produced seeds which contained 21-33% more oil and 24-30% more protein per seed than those of the wild type (WT). The increased oil content was probably because of the enhanced FA and TAG synthetic activity. The seed size and weight were both increased accordingly. In addition, the seed number per silique and silique number per plant had no changes in transgenic plants. Taken together, our results demonstrated that seed specific overexpression of AtFAX1 could promote oil accumulation in Arabidopsis seeds and manipulating FA transportation is a feasible strategy for increasing the seed oil content. Copyright © 2018 Elsevier Inc. All rights reserved.

  20. Cellular recycling of proteins in seed dormancy alleviation and germination

    Directory of Open Access Journals (Sweden)

    Krystyna Oracz

    2016-07-01

    Full Text Available Each step of the seed-to-seed cycle of plant development including seed germination is characterized by a specific set of proteins. The continual renewal and/or replacement of these biomolecules are crucial for optimal plant adaptation. As proteins are the main effectors inside the cells, their levels need to be tightly regulated. This is partially achieved by specific proteolytic pathways via multicatalytic protease complexes defined as 20S and 26S proteasomes. In plants, the 20S proteasome is responsible for degradation of carbonylated proteins, while the 26S being a part of ubiquitin-proteasome pathway (UPP is known to be involved in proteolysis of phytohormone signaling regulators. On the other hand, the role of translational control of plant development is also well documented, especially in the context of pollen tube growth and light signaling. Despite the current progress that has been made in seed biology, the sequence of cellular events that determine if the seed can germinate or not are still far from complete understanding. The role and mechanisms of regulation of proteome composition during processes occurring in the plant’s photosynthetic tissues have been well characterized since many years, but in nonphotosynthetic seeds it has emerged as a tempting research task only since the last decade. This review discusses the recent discoveries providing insights into the role of protein turnover in seed dormancy alleviation, and germination, with a focus on the control of translation and proteasomal proteolysis. The presented novel data of translatome profiling in seeds highlighted that post-transcriptional regulation of germination results from a timely regulated initiation of translation. In addition, the importance of 26S proteasome in the degradation of regulatory elements of cellular signaling and that of the 20S complex in proteolysis of specific carbonylated proteins in hormonal- and light-dependent processes occurring in seeds is

  1. Kinetic studies of adsorption of Cu (II) from aqueous solution by coriander seeds (Coriandrum Sativum)

    Science.gov (United States)

    Kadiri, L.; Lebkiri, A.; Rifi, E. H.; Ouass, A.; Essaadaoui, Y.; Lebkiri, I.; Hamad, H.

    2018-05-01

    The adsorption of copper ions Cu2+ by Coriandrum Sativum seeds (CSS) from aqueous solution was studied in order to highlight the importance of coriander seeds as a potential tool in the treatment of wastewaters containing heavy metals. The kinetic studies of adsorption of Cu (II) were discussed using the spectroscopic technique "Inducting Coupled Plasma" (ICP). The effects of initial copper ion concentration and contact time were determined. All results show that coriander seeds have, over their culinary and medicinal benefits, a significant adsorbent power of copper ions.

  2. Instabilities in a nonstationary model of self-gravitating disks. III. The phenomenon of lopsidedness and a comparison of perturbation modes

    Science.gov (United States)

    Mirtadjieva, K. T.; Nuritdinov, S. N.; Ruzibaev, J. K.; Khalid, Muhammad

    2011-06-01

    This is an examination of the gravitational instability of the major large-scale perturbation modes for a fixed value of the azimuthal wave number m = 1 in nonlinearly nonstationary disk models with isotropic and anisotropic velocity diagrams for the purpose of explaining the displacement of the nucleus away from the geometric center (lopsidedness) in spiral galaxies. Nonstationary analogs of the dispersion relations for these perturbation modes are obtained. Critical diagrams of the initial virial ratio are constructed from the rotation parameters for the models in each case. A comparative analysis is made of the instability growth rates for the major horizontal perturbation modes in terms of two models, and it is found that, on the average, the instability growth rate for the m = 1 mode with a radial wave number N = 3 almost always has a clear advantage relative to the other modes. An analysis of these results shows that if the initial total kinetic energy in an isotropic model is no more than 12.4% of the initial potential energy, then, regardless of the value of the rotation parameter Ω, an instability of the radial motions always occurs and causes the nucleus to shift away from the geometrical center. This instability is aperiodic when Ω = 0 and is oscillatory when Ω ≠ 0 . For the anisotropic model, this kind of structure involving the nucleus develops when the initial total kinetic energy in the model is no more than 30.6% of the initial potential energy.

  3. Closed form bound-state perturbation theory

    Directory of Open Access Journals (Sweden)

    Ollie J. Rose

    1980-01-01

    Full Text Available The perturbed Schrödinger eigenvalue problem for bound states is cast into integral form using Green's Functions. A systematic algorithm is developed and applied to the resulting equation giving rise to approximate solutions expressed as functions of the given perturbation parameter. As a by-product, convergence radii for the traditional Rayleigh-Schrödinger and Brillouin-Wigner perturbation theories emerge in a natural way.

  4. On summation of perturbation expansions

    International Nuclear Information System (INIS)

    Horzela, A.

    1985-04-01

    The problem of the restoration of physical quantities defined by divergent perturbation expansions is analysed. The Pad'e and Borel summability is proved for alternating perturbation expansions with factorially growing coefficients. The proof is based on the methods of the classical moments theory. 17 refs. (author)

  5. Perturbation theory and collision probability formalism. Vol. 2

    Energy Technology Data Exchange (ETDEWEB)

    Nasr, M [National Center for Nuclear Safety and Radiation Control, Atomic Energy Authority, Cairo (Egypt)

    1996-03-01

    Perturbation theory is commonly used in evaluating the activity effects, particularly those resulting from small and localized perturbation in multiplying media., e.g. in small sample reactivity measurements. The Boltzmann integral transport equation is generally used for evaluating the direct and adjoint fluxes in the heterogenous lattice cells to be used in the perturbation equations. When applying perturbation theory in this formalism, a term involving the perturbation effects on the special transfer kernel arises. This term is difficult to evaluate correctly, since it involves an integration all over the entire system. The main advantage of the perturbation theory which is the limitation of the integration procedure on the perturbation region is found to be of no practical use in such cases. In the present work, the perturbation equation in the collision probability formalism is analyzed. A mathematical treatment of the term in question is performed. A new mathematical expression for this term is derived. The new expression which can be estimated easily is derived.

  6. Anticipation of direction and time of perturbation modulates the onset latency of trunk muscle responses during sitting perturbations.

    Science.gov (United States)

    Milosevic, Matija; Shinya, Masahiro; Masani, Kei; Patel, Kramay; McConville, Kristiina M V; Nakazawa, Kimitaka; Popovic, Milos R

    2016-02-01

    Trunk muscles are responsible for maintaining trunk stability during sitting. However, the effects of anticipation of perturbation on trunk muscle responses are not well understood. The objectives of this study were to identify the responses of trunk muscles to sudden support surface translations and quantify the effects of anticipation of direction and time of perturbation on the trunk neuromuscular responses. Twelve able-bodied individuals participated in the study. Participants were seated on a kneeling chair and support surface translations were applied in the forward and backward directions with and without direction and time of perturbation cues. The trunk started moving on average approximately 40ms after the perturbation. During unanticipated perturbations, average latencies of the trunk muscle contractions were in the range between 103.4 and 117.4ms. When participants anticipated the perturbations, trunk muscle latencies were reduced by 16.8±10.0ms and the time it took the trunk to reach maximum velocity was also reduced, suggesting a biomechanical advantage caused by faster muscle responses. These results suggested that trunk muscles have medium latency responses and use reflexive mechanisms. Moreover, anticipation of perturbation decreased trunk muscles latencies, suggesting that the central nervous system modulated readiness of the trunk based on anticipatory information. Copyright © 2015 Elsevier Ltd. All rights reserved.

  7. Physical Methods for Seed Invigoration: Advantages and Challenges in Seed Technology.

    Science.gov (United States)

    Araújo, Susana de Sousa; Paparella, Stefania; Dondi, Daniele; Bentivoglio, Antonio; Carbonera, Daniela; Balestrazzi, Alma

    2016-01-01

    In the context of seed technology, the use of physical methods for increasing plant production offers advantages over conventional treatments based on chemical substances. The effects of physical invigoration treatments in seeds can be now addressed at multiple levels, ranging from morpho-structural aspects to changes in gene expression and protein or metabolite accumulation. Among the physical methods available, "magneto-priming" and irradiation with microwaves (MWs) or ionizing radiations (IRs) are the most promising pre-sowing seed treatments. "Magneto-priming" is based on the application of magnetic fields and described as an eco-friendly, cheap, non-invasive technique with proved beneficial effects on seed germination, vigor and crop yield. IRs, as γ-rays and X-rays, have been widely regarded as a powerful tool in agricultural sciences and food technology. Gamma-rays delivered at low dose have showed to enhance germination percentage and seedling establishment, acting as an actual 'priming' treatment. Different biological effects have been observed in seeds subjected to MWs and X-rays but knowledge about their impact as seed invigoration agent or stimulatory effects on germination need to be further extended. Ultraviolet (UV) radiations, namely UV-A and UV-C have shown to stimulate positive impacts on seed health, germination, and seedling vigor. For all mentioned physical treatments, extensive fundamental and applied research is still needed to define the optimal dose, exposition time, genotype- and environment-dependent irradiation conditions. Electron paramagnetic resonance has an enormous potential in seed technology not fully explored to monitor seed invigoration treatments and/or identifying the best suitable irradiation dose or time-point to stop the treatment. The present manuscript describes the use of physical methods for seed invigoration, while providing a critical discussion on the constraints and advantages. The future perspectives related to

  8. Physical Methods for Seed Invigoration: Advantages and Challenges in Seed Technology

    Science.gov (United States)

    Araújo, Susana de Sousa; Paparella, Stefania; Dondi, Daniele; Bentivoglio, Antonio; Carbonera, Daniela; Balestrazzi, Alma

    2016-01-01

    In the context of seed technology, the use of physical methods for increasing plant production offers advantages over conventional treatments based on chemical substances. The effects of physical invigoration treatments in seeds can be now addressed at multiple levels, ranging from morpho-structural aspects to changes in gene expression and protein or metabolite accumulation. Among the physical methods available, “magneto-priming” and irradiation with microwaves (MWs) or ionizing radiations (IRs) are the most promising pre-sowing seed treatments. “Magneto-priming” is based on the application of magnetic fields and described as an eco-friendly, cheap, non-invasive technique with proved beneficial effects on seed germination, vigor and crop yield. IRs, as γ-rays and X-rays, have been widely regarded as a powerful tool in agricultural sciences and food technology. Gamma-rays delivered at low dose have showed to enhance germination percentage and seedling establishment, acting as an actual ‘priming’ treatment. Different biological effects have been observed in seeds subjected to MWs and X-rays but knowledge about their impact as seed invigoration agent or stimulatory effects on germination need to be further extended. Ultraviolet (UV) radiations, namely UV-A and UV-C have shown to stimulate positive impacts on seed health, germination, and seedling vigor. For all mentioned physical treatments, extensive fundamental and applied research is still needed to define the optimal dose, exposition time, genotype- and environment-dependent irradiation conditions. Electron paramagnetic resonance has an enormous potential in seed technology not fully explored to monitor seed invigoration treatments and/or identifying the best suitable irradiation dose or time-point to stop the treatment. The present manuscript describes the use of physical methods for seed invigoration, while providing a critical discussion on the constraints and advantages. The future perspectives

  9. Physical methods for seed vigourization: advantages and challenges in seed technology

    Directory of Open Access Journals (Sweden)

    Susana eAraújo

    2016-05-01

    Full Text Available In the context of seed technology, the use of physical methods for increasing plant production offers advantages over conventional treatments based on chemical substances. The effects of physical vigourization treatments in seeds can be now addressed at multiple levels, ranging from morpho-structural aspects to changes in gene expression and protein or metabolite accumulation. Among the physical methods available, magneto-priming and irradiation with microwaves or ionizing radiations are the most promissory pre-sowing seed treatments. Magneto-priming is based on the application of magnetic fields and described as an eco-friendly, cheap, non-invasive technique with proved beneficial effects on seed germination, vigour and crop yield. Ionizing radiations, as gamma-rays and X-rays, have been widely regarded as a powerful tool in agricultural sciences and food technology. Gamma-rays delivered at low dose have showed to enhance germination percentage and seedling establishment, acting as an actual ‘priming’ treatment. Different biological effects have been observed in seeds subjected to microwaves and X-rays but knowledge about their impact as seed vigourization agent or stimulatory effects on germination need to be further extended. Ultraviolet (UV radiations, namely UV-A and UV-C have shown to stimulate positive impacts on seed health, germination and seedling vigour. For all mentioned physical treatments, extensive fundamental and applied research is still needed to define the optimal dose, exposition time, genotype- and environment-dependent irradiation conditions. Electron paramagnetic resonance (EPR has an enormous potential in seed technology not fully explored to monitor seed vigourization treatments and/or identifying the best suitable irradiation dose or time-point to stop the treatment. The present manuscript describes the use of physical methods for seed vigourization, while providing a critical discussion on the constraints and

  10. Chemical Characteristics of Pumpkin Seed Tempeh From Soybean and Pumpkin Seeds

    OpenAIRE

    Pujilestari, Shanti; Sandrasari, Diny A; Marida, Rimmaria

    2017-01-01

    The aim of this research was to find the effect of the combination of soybean and pumpkin seeds on the chemical characteristics of pumpkin seed tempeh. The pumpkin seed tempeh samples were analyzed for its water, ash, protein, fat, carbohydrate and crude fiber. Meanwhile, support data were isoflavone and zinc. Sensory hedonic was conducted by 25 untrained panelists for selecting the best formulation of soybean and pumpkin seeds in tempeh. The result shows the formulation of soybean and pumpki...

  11. Quantifying uncertainty in Gulf of Mexico forecasts stemming from uncertain initial conditions

    KAUST Repository

    Iskandarani, Mohamed; Le Hé naff, Matthieu; Srinivasan, Ashwanth; Knio, Omar

    2016-01-01

    Polynomial Chaos (PC) methods are used to quantify the impacts of initial conditions uncertainties on oceanic forecasts of the Gulf of Mexico circulation. Empirical Orthogonal Functions are used as initial conditions perturbations with their modal

  12. Physical properties of sunflower seeds during drying

    Directory of Open Access Journals (Sweden)

    Thaís Adriana de Souza Smaniotto

    2017-03-01

    Full Text Available The aim of this work was to determine the effect that the moisture content has on the physical properties of sunflower seeds. The cultivar Olisun 3, with an initial moisture content of 34.1 (% wb, was used and then subjected to drying in an oven with forced air ventilation under three temperature conditions: 40, 60 and 80 °C. The reduction in the moisture content during drying was monitored by the gravimetric method until it reached a final moisture content of 8.0 ± 1.0 (% wb. The physical properties were analysed: the bulk density, true density, intergranular porosity and volumetric shrinkage of the mass and unit and terminal velocity. The reduction in the moisture content influenced the physical properties of sunflower seeds and caused a decrease in the intergranular porosity, bulk density and true density at all examined temperatures. The mass and volumetric contractions of the unit and reduction in shrinkage rates all increased with the drying of sunflower seeds at all studied temperatures. The terminal velocity increased as the moisture content of the grains increased, which was more evident at the drying temperature of 80 °C.

  13. Oil palm seed distribution

    Directory of Open Access Journals (Sweden)

    Durand-Gasselin Tristan

    2005-03-01

    Full Text Available For a tropical plant, the oil palm commodity chain has the peculiarity of possessing a major seed production sector for reasons that are primarily genetic. This seed sector has numerous original aspects. Breeders are also propagators and usually also distribute their seeds. Oil palm seeds are semi-recalcitrant: they display pseudo-dormancy. Achieving seed germination is difficult and requires lengthy treatments and special installations. This restriction greatly influences seed distribution and the role of the different stakeholders in the commodity chain. It was only once it had been discovered how the “sh” gene functioned, which controls shell thickness, and when it became necessary to produce “tenera” seeds derived from exclusively “dura x pisifera” crosses, that a true seed market developed. In addition it is difficult to organize seed distribution to smallholders. This is partly due to difficulties that the profession, or a State-run organization, has in controlling middlemen networks, and partly to the absence of any protective systems (UPOV, plant breeder certificate, etc. that generally oblige breeders to preserve and propagate parents in their own installations. In fact there are major inequalities in the access to seeds between agroindustry and smallholders. Another peculiarity of the oil palm seed market is the virtually total absence of guarantees for buyers: the quality of the research conducted by breeders, the seed production strategies necessary for transferring genetic progress, and the technical quality of production. The only guarantee today comes from the relations of confidence established year after year between breeders/distributors and growers. In this fields, research can lead to some proposals: molecular biology offers some interesting prospects for certifying seed quality and social science develop effective communication methods.

  14. Seeded emulsion polymerization of butadiene. 1. The propagation rate coefficient

    NARCIS (Netherlands)

    Verdurmen, E.M.F.J.; Dohmen, E.H.M.; Verstegen, J.M.; Maxwell, I.A.; German, A.L.; Gilbert, R.G.

    1993-01-01

    The kinetics of the emulsifier-free, seeded polymn. of butadiene (I) at 60 Deg in Smith-Ewart interval III were studied in presence of Na peroxodisulfate initiator and tert-dodecyl mercaptan. The fractional conversion was based on gravimetrically calibrated online densitometry and was highly

  15. Secondary isocurvature perturbations from acoustic reheating

    Science.gov (United States)

    Ota, Atsuhisa; Yamaguchi, Masahide

    2018-06-01

    The superhorizon (iso)curvature perturbations are conserved if the following conditions are satisfied: (i) (each) non adiabatic pressure perturbation is zero, (ii) the gradient terms are ignored, that is, at the leading order of the gradient expansion (iii) (each) total energy momentum tensor is conserved. We consider the case with the violation of the last two requirements and discuss the generation of secondary isocurvature perturbations during the late time universe. Second order gradient terms are not necessarily ignored even if we are interested in the long wavelength modes because of the convolutions which may pick products of short wavelength perturbations up. We then introduce second order conserved quantities on superhorizon scales under the conditions (i) and (iii) even in the presence of the gradient terms by employing the full second order cosmological perturbation theory. We also discuss the violation of the condition (iii), that is, the energy momentum tensor is conserved for the total system but not for each component fluid. As an example, we explicitly evaluate second order heat conduction between baryons and photons due to the weak Compton scattering, which dominates during the period just before recombination. We show that such secondary effects can be recast into the isocurvature perturbations on superhorizon scales if the local type primordial non Gaussianity exists a priori.

  16. Initial conditions for hydrodynamics from weakly coupled pre-equilibrium evolution

    International Nuclear Information System (INIS)

    Mazeliauskas, Aleksas

    2017-01-01

    We use leading order effective kinetic theory to simulate the pre-equilibrium evolution of transverse energy and flow perturbations in heavy-ion collisions. We provide a Green function which propagates the initial perturbations of the energy-momentum tensor to a time when hydrodynamics becomes applicable. With this map, the pre-thermal evolution from saturated nuclei to hydrodynamics can be modeled in the framework of weakly coupled QCD. (paper)

  17. Generalized chiral perturbation theory

    International Nuclear Information System (INIS)

    Knecht, M.; Stern, J.

    1994-01-01

    The Generalized Chiral Perturbation Theory enlarges the framework of the standard χPT (Chiral Perturbation Theory), relaxing certain assumptions which do not necessarily follow from QCD or from experiment, and which are crucial for the usual formulation of the low energy expansion. In this way, experimental tests of the foundations of the standard χPT become possible. Emphasis is put on physical aspects rather than on formal developments of GχPT. (author). 31 refs

  18. Fractional Differential Equations in Terms of Comparison Results and Lyapunov Stability with Initial Time Difference

    Directory of Open Access Journals (Sweden)

    Coşkun Yakar

    2010-01-01

    Full Text Available The qualitative behavior of a perturbed fractional-order differential equation with Caputo's derivative that differs in initial position and initial time with respect to the unperturbed fractional-order differential equation with Caputo's derivative has been investigated. We compare the classical notion of stability to the notion of initial time difference stability for fractional-order differential equations in Caputo's sense. We present a comparison result which again gives the null solution a central role in the comparison fractional-order differential equation when establishing initial time difference stability of the perturbed fractional-order differential equation with respect to the unperturbed fractional-order differential equation.

  19. Phenoloxidase and melanization test for mango seed weevil

    International Nuclear Information System (INIS)

    Heather, N.W.

    1999-01-01

    This project was initiated to determine whether the phenoloxidase test successfully developed for fruit flies would be applicable to mango seed weevil, Sternochetus mangiferae (Fabricius). Mango seed weevil represents a quarantine impediment to the entry of mangoes to mainland USA and some other countries. It is not a destructive pest and rarely causes fruit damage even in late maturing varieties in which adults can emerge from ripe fruit. The main problem with the weevils come from nursery propagators who are concerned about possible effects on germination. It is questionable whether this is adequate justification for the level of quarantine importance with which this pest is currently regarded. It should not be confused with the mango pulp weevil Sternochetus frigidus Fabricius which does damage all infested fruit. (author)

  20. Quality of cowpea seeds treated with chemicals and stored in controlled and uncontrolled temperature and humidity conditions

    Directory of Open Access Journals (Sweden)

    Lucicléia Mendes de Oliveira

    2015-06-01

    Full Text Available The cowpea is a Fabaceae originated in Africa cultivated in the northern and northeastern of Brazil, where stands out as the main source of protein for the population. For the establishment of culture, seeds are treated to control and prevent pest attacks and diseases, can also attach nutrients to the seeds which will be available for plant development. The objective of the research was to evaluate the performance of cowpea seeds treated with chemical products and stored in controlled and uncontrolled temperature and humidity conditions. The following seeds treatments were applied: control (no treatment; micronutrient Comol 118, insecticide thiamethoxam, fipronil and pyraclostrobin+thiophanate-methyl and imidacloprid+thiodicarb were then stored in a cold environment and natural. The assessment of physiological seed quality was made initially and every 45 days through the germination and vigor. Among all products used, the imidacloprid + thiodicarb and fipronil + pyraclostrobin + thiophanate methyl provides stimulating effect on seed performance; seeds treated with thiamethoxam were less affected by storage than the untreated seeds; seeds treated with micronutrients exhibits similar behavior to untreated seeds and storage in a controlled environment better preserves the seed physiological quality.

  1. Bulk YBCO seeded with 45°–45° bridge-seeds of different lengths

    International Nuclear Information System (INIS)

    Shi, Y-H; Durrell, J H; Dennis, A R; Cardwell, D A

    2013-01-01

    Single grain, (RE)BCO (rare earth–barium–copper oxide) bulk superconductors in large or complicated geometries are required for a variety of potential applications, such as in motors and generators and magnetic shielding devices. As a result, top, multi-seeded, melt growth has been investigated over the past 15 years in an attempt to enlarge the size of (RE)BCO single grains specifically for such applications. Of these multi-seeding techniques, so-called bridge-seeding provides the best alignment of two seeds in a single grain growth process. Here we report, for the first time, the successful growth of YBCO (yttrium–barium–copper oxide) using a special, 45°–45°, arrangement of bridge-seeds. The superconducting properties, including trapped field, of the multi-seeded YBCO grains have been measured for different bridge lengths of the 45°–45° bridge-seeds. The boundaries at the impinging growth front and the growth features of the top, multi-seeded surface and cross-section of the multi-seeded, samples have been analysed using optical microscopy. The results suggest that an impurity-free boundary between the two seeds of each leg of the bridge-seed can form when 45°–45° bridge-seeds are used to enlarge the size of YBCO grains. (paper)

  2. Proanthocyanidins in seed coat tegmen and endospermic cap inhibit seed germination in Sapium sebiferum

    Directory of Open Access Journals (Sweden)

    Faheem Afzal Shah

    2018-04-01

    Full Text Available Sapium sebiferum, an ornamental and bio-energetic plant, is propagated by seed. Its seed coat contains germination inhibitors and takes a long time to stratify for germination. In this study, we discovered that the S. sebiferum seed coat (especially the tegmen and endospermic cap (ESC contained high levels of proanthocyanidins (PAs. Seed coat and ESC removal induced seed germination, whereas exogenous application with seed coat extract (SCE or PAs significantly inhibited this process, suggesting that PAs in the seed coat played a major role in regulating seed germination in S. sebiferum. We further investigated how SCE affected the expression of the seed-germination-related genes. The results showed that treatment with SCE upregulated the transcription level of the dormancy-related gene, gibberellins (GAs suppressing genes, abscisic acid (ABA biosynthesis and signalling genes. SCE decreased the transcript levels of ABA catabolic genes, GAs biosynthesis genes, reactive oxygen species genes and nitrates-signalling genes. Exogenous application of nordihydroguaiaretic acid, gibberellic acid, hydrogen peroxide and potassium nitrate recovered seed germination in seed-coat-extract supplemented medium. In this study, we highlighted the role of PAs, and their interactions with the other germination regulators, in the regulation of seed dormancy in S. sebiferum.

  3. Seedling performance within eight different seed-size alpine forbs under experimentation with irradiance and nutrient gradients

    International Nuclear Information System (INIS)

    Dong, W.; Jun, Z.Y.; Lin, W.G.; Jin, F.

    2014-01-01

    Relative performance of seedlings of species with different seed sizes may vary in response to resource availability, and may affect seedling growth. The objective was to test this hypothesis from alpine forbs species in the Qinghai-Tibetan Plateau. We examined the relative growth rate, allocation and performances of eight native forbs species covering a wide range of seed size in response to four light and three nutrient regimes. Light availability had a significant effect on seedling emergence time, but not on other seedling morphological performances. Seedling emergence time and seed size were negatively correlated with each other for three species within Asteraceae family, i.e. heaviest seeds emerged earlier. Seed size, nutrient availability and their interaction affected most of studied morphological and growth traits of seedlings. Fertilisation modified the relationship between seed size and seedling biomass. Our study showed that seed size and nutrient availability had significant effects on seedling performance in alpine meadows. Seedlings from the larger-seed species presented stronger advantage in initial seedling mass and height under most of resources conditions. (author)

  4. Seed source, seed traits, and frugivore habits: Implications for dispersal quality of two sympatric primates.

    Science.gov (United States)

    Benítez-Malvido, Julieta; González-Di Pierro, Ana Ma; Lombera, Rafael; Guillén, Susana; Estrada, Alejandro

    2014-06-01

    • Premise of the study: Frugivore selection of fruits and treatment of seeds together with seed deposition site are crucial for the population dynamics of vertebrate-dispersed plants. However, frugivore species may influence dispersal quality differently even when feeding on the same fruit species and, while animals disperse some seeds, others simply fall beneath the parent plant.• Methods: In southern Mexico, we investigated to see if within-species seed traits (i.e., length, width, weight, and volume) and germination success differed according to seed source. For five tropical tree species we obtained ingested seeds from two sources, howler monkey (Alouatta pigra) and spider monkey (Ateles geoffroyi) feces; and noningested seeds from two sources, the ground and tree crowns (with predispersed seeds used as control).• Key results: A principal components' analysis showed that traits of seeds ingested by howler monkeys differed from other sources while seeds ingested by spider monkeys were similar to noningested seeds. Howlers consumed on average the larger seeds in Ampelocera hottlei, Brosimum lactescens, and Dialium guianense. Both primate species consumed the smaller seeds in Spondias mombin, while no seed trait differences among seed sources were found in Spondias radlkoferi. For all five tree species, germination rate was greatest for seeds ingested by howler monkeys.• Conclusions: For the studied plant species, seed ingestion by howler monkeys confers higher dispersal quality than ingestion by spider monkeys or nondispersal. Dispersal services of both primate species, however, are not redundant and may contribute to germination heterogeneity within plant populations in tropical forests. © 2014 Botanical Society of America, Inc.

  5. Transient medial prefrontal perturbation reduces false memory formation.

    Science.gov (United States)

    Berkers, Ruud M W J; van der Linden, Marieke; de Almeida, Rafael F; Müller, Nils C J; Bovy, Leonore; Dresler, Martin; Morris, Richard G M; Fernández, Guillén

    2017-03-01

    Knowledge extracted across previous experiences, or schemas, benefit encoding and retention of congruent information. However, they can also reduce specificity and augment memory for semantically related, but false information. A demonstration of the latter is given by the Deese-Roediger-McDermott (DRM) paradigm, where the studying of words that fit a common semantic schema are found to induce false memories for words that are congruent with the given schema, but were not studied. The medial prefrontal cortex (mPFC) has been ascribed the function of leveraging prior knowledge to influence encoding and retrieval, based on imaging and patient studies. Here, we used transcranial magnetic stimulation (TMS) to transiently perturb ongoing mPFC processing immediately before participants performed the DRM-task. We observed the predicted reduction in false recall of critical lures after mPFC perturbation, compared to two control groups, whereas veridical recall and recognition memory performance remained similar across groups. These data provide initial causal evidence for a role of the mPFC in biasing the assimilation of new memories and their consolidation as a function of prior knowledge. Copyright © 2016 Elsevier Ltd. All rights reserved.

  6. Cone and seed yields in white spruce seed production areas

    Science.gov (United States)

    John A. Pitcher

    1966-01-01

    The source of seed is an important consideration in the reforestation program on the National Forests in the North Central Region. Thirty-five seed production areas have been set up in the Region, along the lines proposed by the North Central Forest Experiment Station, to provide control of seed source. Red pine, white pine, shortleaf and loblolly pine, and white...

  7. Stepping stability: effects of sensory perturbation

    Directory of Open Access Journals (Sweden)

    Krebs David E

    2005-05-01

    Full Text Available Abstract Background Few tools exist for quantifying locomotor stability in balance impaired populations. The objective of this study was to develop and evaluate a technique for quantifying stability of stepping in healthy people and people with peripheral (vestibular hypofunction, VH and central (cerebellar pathology, CB balance dysfunction by means a sensory (auditory perturbation test. Methods Balance impaired and healthy subjects performed a repeated bench stepping task. The perturbation was applied by suddenly changing the cadence of the metronome (100 beat/min to 80 beat/min at a predetermined time (but unpredictable by the subject during the trial. Perturbation response was quantified by computing the Euclidian distance, expressed as a fractional error, between the anterior-posterior center of gravity attractor trajectory before and after the perturbation was applied. The error immediately after the perturbation (Emax, error after recovery (Emin and the recovery response (Edif were documented for each participant, and groups were compared with ANOVA. Results Both balance impaired groups exhibited significantly higher Emax (p = .019 and Emin (p = .028 fractional errors compared to the healthy (HE subjects, but there were no significant differences between CB and VH groups. Although response recovery was slower for CB and VH groups compared to the HE group, the difference was not significant (p = .051. Conclusion The findings suggest that individuals with balance impairment have reduced ability to stabilize locomotor patterns following perturbation, revealing the fragility of their impairment adaptations and compensations. These data suggest that auditory perturbations applied during a challenging stepping task may be useful for measuring rehabilitation outcomes.

  8. Aspects of perturbative QCD in Monte Carlo shower models

    International Nuclear Information System (INIS)

    Gottschalk, T.D.

    1986-01-01

    The perturbative QCD content of Monte Carlo models for high energy hadron-hadron scattering is examined. Particular attention is given to the recently developed backwards evolution formalism for initial state parton showers, and the merging of parton shower evolution with hard scattering cross sections. Shower estimates of K-factors are discussed, and a simple scheme is presented for incorporating 2 → QCD cross sections into shower model calculations without double counting. Additional issues in the development of hard scattering Monte Carlo models are summarized. 69 references, 20 figures

  9. Problems at the interface between perturbative and nonperturbative quantum chromodynamics

    International Nuclear Information System (INIS)

    Brodsky, S.J.; Bodwin, G.T.; Lepage, G.P.

    1983-06-01

    Predictions based on perturbative QCD rest on three premises: (1) that hadronic interactions become weak in strength at small invariant separation; (2) that the perturbative expansion in α/sub s/(Q) is well-defined; and (3) factorization: all effects of collinear singularities, confinement, nonperturbative interactions, and bound state dynamics can be isolated at large momentum transfer in terms of structure functions, fragmentation functions, or in the case of exclusive processes, distribution amplitudes. The assumption that the perturbative expansion for hard scattering amplitudes converges has certainly not been demonstrated; in addition, there are serious ambiguities concerning the choice of renormalization scheme and scale choice Q 2 for the expansion in α/sub s/(Q 2 ). We will discuss a new procedure to at least partly rectify the latter problem. In the case of exclusive processes, the factorization of hadronic amplitudes at large momentum transfer in the form of distribution amplitudes convoluted with hard scattering quark-gluon subprocess amplitudes can be demonstrated systematically to all orders in α/sub s/(Q 2 ). In the case of inclusive reactions, factorization remains an ansatz; general all-orders proofs do not exist because of the complications of soft initial state interactions for hadron-induced processes; thus far factorization has only been verified to two loops beyond lowest order in a regime where the applicability of perturbation theory is in doubt. However, we shall show that a necessary condition for the validity of factorization in inclusive reactions is that the momentum transfer must be large compared to the (rest frame) length of the target. We review the present status of the factorization ansatz. 52 references

  10. Cosmological perturbations beyond linear order

    CERN Multimedia

    CERN. Geneva

    2013-01-01

    Cosmological perturbation theory is the standard tool to understand the formation of the large scale structure in the Universe. However, its degree of applicability is limited by the growth of the amplitude of the matter perturbations with time. This problem can be tackled with by using N-body simulations or analytical techniques that go beyond the linear calculation. In my talk, I'll summarise some recent efforts in the latter that ameliorate the bad convergence of the standard perturbative expansion. The new techniques allow better analytical control on observables (as the matter power spectrum) over scales very relevant to understand the expansion history and formation of structure in the Universe.

  11. Instabilities in mimetic matter perturbations

    Energy Technology Data Exchange (ETDEWEB)

    Firouzjahi, Hassan; Gorji, Mohammad Ali [School of Astronomy, Institute for Research in Fundamental Sciences (IPM), P.O. Box 19395-5531, Tehran (Iran, Islamic Republic of); Mansoori, Seyed Ali Hosseini, E-mail: firouz@ipm.ir, E-mail: gorji@ipm.ir, E-mail: shosseini@shahroodut.ac.ir, E-mail: shossein@ipm.ir [Physics Department, Shahrood University of Technology, P.O. Box 3619995161 Shahrood (Iran, Islamic Republic of)

    2017-07-01

    We study cosmological perturbations in mimetic matter scenario with a general higher derivative function. We calculate the quadratic action and show that both the kinetic term and the gradient term have the wrong sings. We perform the analysis in both comoving and Newtonian gauges and confirm that the Hamiltonians and the associated instabilities are consistent with each other in both gauges. The existence of instabilities is independent of the specific form of higher derivative function which generates gradients for mimetic field perturbations. It is verified that the ghost instability in mimetic perturbations is not associated with the higher derivative instabilities such as the Ostrogradsky ghost.

  12. Vegetative growth response of cotton plants due to growth regulator supply via seeds

    Directory of Open Access Journals (Sweden)

    João Vitor Ferrari

    2015-08-01

    Full Text Available The global cotton industry is distinguished by its numerous industrial uses of the plume as well as by high production costs. Excessive vegetative growth can interfere negatively with productivity, and thus, applying growth regulators is essential for the development of the cotton culture. The objective of this study was to evaluate the development and yield of the cotton cultivar FMT 701 with the application of mepiquat chloride to seeds and leaves. The experimental design used a randomized block design with four replications, arranged in bands.The treatments consisted of mepiquat chloride rates (MC (0, 4, 6, 8 and 10 g a.i. kg-1 of seeds applied directly to the cotton seeds and MC management by foliar spray using a 250 mL ha-1 rates that was administered under the following conditions: divided into four applications (35, 45, 55 and 65 days after emergence; as a single application at 70 days; and without the application of the product. The mepiquat chloride applied to cotton seeds controls the initial plant height and stem diameter, while foliar application reduces the height of the plants. After application to seed, foliar spraying MC promotes increase mass of 20 bolls, however no direct influence amount bolls per plant and yield of cotton seed. Higher cotton seed yield was obtained with a rate of 3.4 g a.i. MC kg-1 seeds.

  13. Gauge-invariant perturbations in a spatially flat anisotropic universe

    International Nuclear Information System (INIS)

    Den, Mitsue.

    1986-12-01

    The gauge-invariant perturbations in a spatially flat anisotropic universe with an arbitrary dimension (= N) are studied. In a previous paper the equations for the perturbations with a wave vector k a in one of the axial directions were derived and their solutions were shown. In this paper the perturbations with k a in arbitrary directions are treated. The remarkable properties are that all three types (scalar, vector, and tensor) of perturbations are generally coupled, so that a density perturbation can be produced also by vector or tensor perturbations. The formulation is quite general, but the behavior of the perturbations is discussed in a simple case such that N = 4 and k a is orthogonal to one of the axial directions. In this case, the perturbations are divided into two groups which are dynamically decoupled from each other. The asymptotic behavior of the perturbations in the group containing the density perturbation is discussed. (author)

  14. Tillage and residue burning affects weed populations and seed banks.

    Science.gov (United States)

    Narwal, S; Sindel, B M; Jessop, R S

    2006-01-01

    An integrated weed management approach requires alternative management practices to herbicide use such as tillage, crop rotations and cultural controls to reduce soil weed seed banks. The objective of this study was to examine the value of different tillage practices and stubble burning to exhaust the seed bank of common weeds from the northern grain region of Australia. Five tillage and burning treatments were incorporated in a field experiment, at Armidale (30 degrees 30'S, 151 degrees 40'E), New South Wales, Australia in July 2004 in a randomized block design replicated four times. The trial was continued and treatments repeated in July 2005 with all the mature plants from the first year being allowed to shed seed in their respective treatment plots. The treatments were (i) no tillage (NT), (ii) chisel ploughing (CP), (iii) mould board ploughing (MBP), (iv) wheat straw burning with no tillage (SBNT) and (v) wheat straw burning with chisel ploughing (SBC). Soil samples were collected before applying treatments and before the weeds flowered to establish the seed bank status of the various weeds in the soil. Wheat was sown after the tillage treatments. Burning treatments were only initiated in the second year, one month prior to tillage treatments. The major weeds present in the seed bank before initiating the trial were Polygonum aviculare, Sonchus oleraceus and Avena fatua. Tillage promoted the germination of other weeds like Hibiscus trionum, Medicago sativa, Vicia sp. and Phalaris paradoxa later in the season in 2004 and Convolvulus erubescens emerged as a new weed in 2005. The MBP treatment in 2004 reduced the weed biomass to a significantly lower level of 55 g/m2 than the other treatments of CP (118 g/m2) and NT plots (196 g/m2) (P < 0.05). However, in 2005 SBC and MBP treatments were similar in reducing the weed biomass. In 2004, the grain yield trend of wheat was significantly different between CP and NT, and MBP and NT (P < 0.05) with maximum yield of 5898

  15. Lattice regularized chiral perturbation theory

    International Nuclear Information System (INIS)

    Borasoy, Bugra; Lewis, Randy; Ouimet, Pierre-Philippe A.

    2004-01-01

    Chiral perturbation theory can be defined and regularized on a spacetime lattice. A few motivations are discussed here, and an explicit lattice Lagrangian is reviewed. A particular aspect of the connection between lattice chiral perturbation theory and lattice QCD is explored through a study of the Wess-Zumino-Witten term

  16. Output synchronization of chaotic systems under nonvanishing perturbations

    Energy Technology Data Exchange (ETDEWEB)

    Lopez-Mancilla, Didier [Departamento de Ciencias Exactas y Tecnologicas, Centro Universitario de los Lagos, Universidad de Guadalajara (CULagos-UdeG), Enrique Diaz de Leon s/n, 47460 Lagos de Moreno, Jal. (Mexico)], E-mail: didier@uabc.mx; Cruz-Hernandez, Cesar [Electronics and Telecommunications Department, Scientific Research and Advanced Studies of Ensenada (CICESE), Km. 107, Carretera Tijuana-Ensenada, 22860 Ensenada, B.C. (Mexico)], E-mail: ccruz@cicese.mx

    2008-08-15

    In this paper, an analysis for chaos synchronization under nonvanishing perturbations is presented. In particular, we use model-matching approach from nonlinear control theory for output synchronization of identical and nonidentical chaotic systems under nonvanishing perturbations in a master-slave configuration. We show that the proposed approach is indeed suitable to synchronize a class of perturbed slaves with a chaotic master system; that is the synchronization error trajectories remain bounded if the perturbations satisfy some conditions. In order to illustrate this robustness synchronization property, we present two cases of study: (i) for identical systems, a pair of coupled Roessler systems, the first like a master and the other like a perturbed slave, and (ii) for nonidentical systems, a Chua's circuit driving a Roessler/slave system with a perturbed control law, in both cases a quantitative analysis on the perturbation is included.

  17. Output synchronization of chaotic systems under nonvanishing perturbations

    International Nuclear Information System (INIS)

    Lopez-Mancilla, Didier; Cruz-Hernandez, Cesar

    2008-01-01

    In this paper, an analysis for chaos synchronization under nonvanishing perturbations is presented. In particular, we use model-matching approach from nonlinear control theory for output synchronization of identical and nonidentical chaotic systems under nonvanishing perturbations in a master-slave configuration. We show that the proposed approach is indeed suitable to synchronize a class of perturbed slaves with a chaotic master system; that is the synchronization error trajectories remain bounded if the perturbations satisfy some conditions. In order to illustrate this robustness synchronization property, we present two cases of study: (i) for identical systems, a pair of coupled Roessler systems, the first like a master and the other like a perturbed slave, and (ii) for nonidentical systems, a Chua's circuit driving a Roessler/slave system with a perturbed control law, in both cases a quantitative analysis on the perturbation is included

  18. Securing Access to Seed: Social Relations and Sorghum Seed Exchange in Eastern Ethiopia

    NARCIS (Netherlands)

    McGuire, S.

    2008-01-01

    Access to seed is crucial for farming, though few studies investigate household-level access in the informal `farmer seed systems¿ which still supply most seed in poor countries. This paper uses empirical data of seed exchange practices for sorghum in eastern Ethiopia to analyze how social

  19. Two-body perturbation theory versus first order perturbation theory: A comparison based on the square-well fluid.

    Science.gov (United States)

    Mercier Franco, Luís Fernando; Castier, Marcelo; Economou, Ioannis G

    2017-12-07

    We show that the Zwanzig first-order perturbation theory can be obtained directly from a truncated Taylor series expansion of a two-body perturbation theory and that such truncation provides a more accurate prediction of thermodynamic properties than the full two-body perturbation theory. This unexpected result is explained by the quality of the resulting approximation for the fluid radial distribution function. We prove that the first-order and the two-body perturbation theories are based on different approximations for the fluid radial distribution function. To illustrate the calculations, the square-well fluid is adopted. We develop an analytical expression for the two-body perturbed Helmholtz free energy for the square-well fluid. The equation of state obtained using such an expression is compared to the equation of state obtained from the first-order approximation. The vapor-liquid coexistence curve and the supercritical compressibility factor of a square-well fluid are calculated using both equations of state and compared to Monte Carlo simulation data. Finally, we show that the approximation for the fluid radial distribution function given by the first-order perturbation theory provides closer values to the ones calculated via Monte Carlo simulations. This explains why such theory gives a better description of the fluid thermodynamic behavior.

  20. Local Seed Business in the Context of Integrated Seed Sector Development

    NARCIS (Netherlands)

    Thijssen, M.H.; Borman, G.D.; Verhoosel, K.S.; Mastenbroek, A.; Heemskerk, Willem

    2015-01-01

    Quality seed is a key input for agriculture, with a direct impact on agricultural production and productivity. Integrated seed sector development (ISSD) is an inclusive approach that recognizes and builds upon a diversity of seed systems in the sector. We use the ISSD approach to guide us in the

  1. Farmers' seed sources and seed quality: 1. Physical and physiological quality

    NARCIS (Netherlands)

    Bishaw, Z.; Struik, P.C.; Gastel, van A.J.G.

    2012-01-01

    Understanding farmers' seed quality problem will enable farmers to devise strategies to improve quality at the farm level. The study was conducted to assess the quality of seed used by farmers from different sources and regions. A total of 304 wheat (Trticium aestivum L. and T. durum L.) seed

  2. Improving Soil Seed Bank Management.

    Science.gov (United States)

    Haring, Steven C; Flessner, Michael L

    2018-05-08

    Problems associated with simplified weed management motivate efforts for diversification. Integrated weed management uses fundamentals of weed biology and applied ecology to provide a framework for diversified weed management programs; the soil seed bank comprises a necessary part of this framework. By targeting seeds, growers can inhibit the propagule pressure on which annual weeds depend for agricultural invasion. Some current management practices affect weed seed banks, such as crop rotation and tillage, but these tools are often used without specific intention to manage weed seeds. Difficulties quantifying the weed seed bank, understanding seed bank phenology, and linking seed banks to emerged weed communities challenge existing soil seed bank management practices. Improved seed bank quantification methods could include DNA profiling of the soil seed bank, mark and recapture, or 3D LIDAR mapping. Successful and sustainable soil seed bank management must constrain functionally diverse and changing weed communities. Harvest weed seed controls represent a step forward, but over-reliance on this singular technique could make it short-lived. Researchers must explore tools inspired by other pest management disciplines, such as gene drives or habitat modification for predatory organisms. Future weed seed bank management will combine multiple complementary practices that enhance diverse agroecosystems. This article is protected by copyright. All rights reserved.

  3. Higher accuracy analytical approximations to a nonlinear oscillator with discontinuity by He's homotopy perturbation method

    International Nuclear Information System (INIS)

    Belendez, A.; Hernandez, A.; Belendez, T.; Neipp, C.; Marquez, A.

    2008-01-01

    He's homotopy perturbation method is used to calculate higher-order approximate periodic solutions of a nonlinear oscillator with discontinuity for which the elastic force term is proportional to sgn(x). We find He's homotopy perturbation method works very well for the whole range of initial amplitudes, and the excellent agreement of the approximate frequencies and periodic solutions with the exact ones has been demonstrated and discussed. Only one iteration leads to high accuracy of the solutions with a maximal relative error for the approximate period of less than 1.56% for all values of oscillation amplitude, while this relative error is 0.30% for the second iteration and as low as 0.057% when the third-order approximation is considered. Comparison of the result obtained using this method with those obtained by different harmonic balance methods reveals that He's homotopy perturbation method is very effective and convenient

  4. Influence the Rubber Seed Type and Altitude on Characteristic of Seed, Oil and Biodiesel

    Directory of Open Access Journals (Sweden)

    Salni Salni

    2017-06-01

    Full Text Available This research studies the influence of the type of rubber seed that is superior and local, altitude plant in South Sumatra province to the characteristic of seed, oil and biodiesel (methyl ester. Rubber plants planted from local rubber seed by seeds seedlings and superior rubber seed by selected clones. In the study, rubber plants planted at a different altitude, namely in Banyuasin district (18 m above sea level, Prabumulih District (176 m above sea level and Lahat District (627 m above sea level. The results showed that the weight of the flour, the water content and ash content in the local rubber seeds larger than the superior rubber seed for all altitude, but oil content a large in the superior rubber seeds. The major of fatty acids in the rubber seed oil in all types and altitude are a linoleic acid with a different percentage except local rubber seed oil from Lahat district with the large percentage of octadecanoic acid. Free fatty acids in the oil from the superior seeds rubber of 13.897-15.494 % large than local rubber seed oil was found 9.786-10.399 % for all altitude. By esterification process using sulfuric acid catalyst, Free Fatty Acid (FFA can be reduced to ≤ 2 %. The methyl ester made from the transesterification process of rubber seed oil after esterification using methanol and sodium hydroxide as catalyst. Analysis of methyl esters includes cetane index, flash point, kinematic viscosity, carbon residue, density, moisture content, water and sediment content and distillation compared with SNI 7182 and ASTM 6751-02.  The result indicated that the quality of methyl ester from superior rubber seed oil in the Banyuasin and Prabumulih district better than another methyl ester. The types of rubber seed altitude affect the characteristics of the seed, oil and methyl ester  but the altitude are not significantly different. Keywords: rubber seed, type, altitude, oil, biodiesel Article History: Received March 21st 2017; Received in

  5. Induction of 9-cis-epoxycarotenoid dioxygenase in Arabidopsis thaliana seeds enhances seed dormancy.

    Science.gov (United States)

    Martínez-Andújar, Cristina; Ordiz, M Isabel; Huang, Zhonglian; Nonogaki, Mariko; Beachy, Roger N; Nonogaki, Hiroyuki

    2011-10-11

    Full understanding of mechanisms that control seed dormancy and germination remains elusive. Whereas it has been proposed that translational control plays a predominant role in germination, other studies suggest the importance of specific gene expression patterns in imbibed seeds. Transgenic plants were developed to permit conditional expression of a gene encoding 9-cis-epoxycarotenoid dioxygenase 6 (NCED6), a rate-limiting enzyme in abscisic acid (ABA) biosynthesis, using the ecdysone receptor-based plant gene switch system and the ligand methoxyfenozide. Induction of NCED6 during imbibition increased ABA levels more than 20-fold and was sufficient to prevent seed germination. Germination suppression was prevented by fluridone, an inhibitor of ABA biosynthesis. In another study, induction of the NCED6 gene in transgenic seeds of nondormant mutants tt3 and tt4 reestablished seed dormancy. Furthermore, inducing expression of NCED6 during seed development suppressed vivipary, precocious germination of developing seeds. These results indicate that expression of a hormone metabolism gene in seeds can be a sole determinant of dormancy. This study opens the possibility of developing a robust technology to suppress or promote seed germination through engineering pathways of hormone metabolism.

  6. Continual integral in perturbation theory

    International Nuclear Information System (INIS)

    Slavnov, A.A.

    1975-01-01

    It is shown that all results obtained by means of continual integration within the framework of perturbation theory are completely equivalent to those obtained by the usual diagram technique and are therfore just as rigorous. A rigorous justification is given for the rules for operating with continual integrals in perturbation theory. (author)

  7. Responses of Seed Germination, Seedling Growth, and Seed Yield Traits to Seed Pretreatment in Maize (Zea mays L.

    Directory of Open Access Journals (Sweden)

    Yu Tian

    2014-01-01

    Full Text Available A series of seed priming experiments were conducted to test the effects of different pretreatment methods to seed germination, seedling growth, and seed yield traits in maize (Zea mays L.. Results indicated that the seeds primed by gibberellins (GA, NaCl, and polyethylene glycol (PEG reagents showed a higher imbibitions rate compared to those primed with water. The final germination percentage and germination rate varied with different reagents significantly (P<0.05. The recommended prime reagents were GA at 10 mg/L, NaCl at 50 mM, and PEG at 15% on account of germination experiment. 15% PEG priming reagent increased shoot and root biomass of maize seedling. The shoot biomass of seedlings after presoaking the seeds with NaCl reagent was significantly higher than the seedlings without priming treatment. No significant differences of plant height, leaf number, and hundred-grain weight were observed between control group and priming treatments. Presoaking with water, NaCl (50 mM, or PEG (15% significantly increased the hundred-grain weight of maize. Therefore, seed pretreatment is proved to be an effective technique to improve the germination performance, seedling growth, and seed yield of maize. However, when compared with the two methods, if immediate sowing is possible, presoaking is recommended to harvest better benefits compared to priming method.

  8. Kato expansion in quantum canonical perturbation theory

    International Nuclear Information System (INIS)

    Nikolaev, Andrey

    2016-01-01

    This work establishes a connection between canonical perturbation series in quantum mechanics and a Kato expansion for the resolvent of the Liouville superoperator. Our approach leads to an explicit expression for a generator of a block-diagonalizing Dyson’s ordered exponential in arbitrary perturbation order. Unitary intertwining of perturbed and unperturbed averaging superprojectors allows for a description of ambiguities in the generator and block-diagonalized Hamiltonian. We compare the efficiency of the corresponding computational algorithm with the efficiencies of the Van Vleck and Magnus methods for high perturbative orders.

  9. Kato expansion in quantum canonical perturbation theory

    Energy Technology Data Exchange (ETDEWEB)

    Nikolaev, Andrey, E-mail: Andrey.Nikolaev@rdtex.ru [Institute of Computing for Physics and Technology, Protvino, Moscow Region, Russia and RDTeX LTD, Moscow (Russian Federation)

    2016-06-15

    This work establishes a connection between canonical perturbation series in quantum mechanics and a Kato expansion for the resolvent of the Liouville superoperator. Our approach leads to an explicit expression for a generator of a block-diagonalizing Dyson’s ordered exponential in arbitrary perturbation order. Unitary intertwining of perturbed and unperturbed averaging superprojectors allows for a description of ambiguities in the generator and block-diagonalized Hamiltonian. We compare the efficiency of the corresponding computational algorithm with the efficiencies of the Van Vleck and Magnus methods for high perturbative orders.

  10. Mycoflora in Exhumed Seeds of Opuntia tomentosa and Its Possible Role in Seed Germination

    Directory of Open Access Journals (Sweden)

    María Esther Sánchez-Coronado

    2011-01-01

    Full Text Available The funicular cover of the Opuntia tomentosa seed limits imbibition; germination occurs only when the funicle is weakened or the funicular valve is removed. We investigated the role of fungi in funicular weakening and seed germination. Seeds that had been either buried in one of two sites or stored in the laboratory were germinated with and without a valve. Disinfected or nondisinfected seeds and their naked embryos were cultivated on agar or PDA. None of the 11 identified fungal genera grew on the disinfected control seeds or the embryos. The mycoflora present on disinfected and nondisinfected exhumed seeds suggest that the fungal colonization occurred in the soil and differed between the burial sites. Exhumed seeds with and without a valve germinated in high percentages, whereas only the control seeds without a valve germinated. Scanning electron micrographs showed that the hyphae penetrated, cracked, and eroded the funicular envelope of exhumed seeds.

  11. Invariant exchange perturbation theory for multicenter systems: Time-dependent perturbations

    International Nuclear Information System (INIS)

    Orlenko, E. V.; Evstafev, A. V.; Orlenko, F. E.

    2015-01-01

    A formalism of exchange perturbation theory (EPT) is developed for the case of interactions that explicitly depend on time. Corrections to the wave function obtained in any order of perturbation theory and represented in an invariant form include exchange contributions due to intercenter electron permutations in complex multicenter systems. For collisions of atomic systems with an arbitrary type of interaction, general expressions are obtained for the transfer (T) and scattering (S) matrices in which intercenter electron permutations between overlapping nonorthogonal states belonging to different centers (atoms) are consistently taken into account. The problem of collision of alpha particles with lithium atoms accompanied by the redistribution of electrons between centers is considered. The differential and total charge-exchange cross sections of lithium are calculated

  12. Proteome analysis of dissected barley seed tissue during germination and radicle elongation

    DEFF Research Database (Denmark)

    Bønsager, Birgit Christine

    2007-01-01

    at the protein or the DNA level. In addition, germination of barley seeds is of interest for the brewing industry since this process corresponds to the steeping process that starts the industrial malting. In the present study a proteomics approach was employed to understand the initial changes in the water...... soluble protein composition of the barley seed upon imbibition and the following events that occur until to 72 h post imbibition (PI). 2D gel electrophoresis of proteins extracted from dissected barley seeds tissues during germination (0-24 h) and the subsequent radicle elongation (24-72 h) describes...... spatio-temporal variations in the protein patterns. Seeds from 8 time points (0, 4, 12, 24, 36, 52, 60, and 72 h PI) were dissected into embryo, aleurone layer and endosperm and small scale protein extractions enabled us to obtain good resolution 2D gels. The 2D gels were compared between the time points...

  13. Strings as perturbations of evolving spin networks

    International Nuclear Information System (INIS)

    Smolin, Lee

    2000-01-01

    One step in the construction of a background independent formulation of string theory is detailed, in which it is shown how perturbative strings may arise as small fluctuations around histories in a formulation of non-perturbative dynamics of spin networks due to Markopoulou. In this formulation the dynamics of spin network states and their generalizations is described in terms of histories which have discrete analogues of the causal structure and many fingered time of Lorentzian spacetimes. Perturbations of these histories turn out to be described in terms of spin systems defined on 2-dimensional timelike surfaces embedded in the discrete spacetime. When the history has a classical limit which is Minkowski spacetime, the action of the perturbation theory is given to leading order by the spacetime area of the surface, as in bosonic string theory. This map between a non-perturbative formulation of quantum gravity and a 1+1 dimensional theory generalizes to a large class of theories in which the group SU(2) i s extended to any quantum group or supergroup. It is argued that a necessary condition for the non-perturbative theory to have a good classical limit is that the resulting 1+1 dimensional theory defines a consistent and stable perturbative string theory

  14. Post-collapse perturbation theory in 1D cosmology - beyond shell-crossing

    Science.gov (United States)

    Taruya, Atsushi; Colombi, Stéphane

    2017-10-01

    We develop a new perturbation theory (PT) treatment that can describe gravitational dynamics of large-scale structure after shell-crossing in the one-dimensional cosmological case. Starting with cold initial conditions, the motion of matter distribution follows at early stages the single-stream regime, which can, in one dimension, be described exactly by the first-order Lagrangian perturbation, I.e. the Zel'dovich solution. However, the single-stream flow no longer holds after shell-crossing and a proper account of the multistream flow is essential for post-collapse dynamics. In this paper, extending previous work by Colombi, we present a perturbative description for the multistream flow after shell-crossing in a cosmological setup. In addition, we introduce an adaptive smoothing scheme to deal with the bulk properties of phase-space structures. The filtering scales in this scheme are linked to the next-crossing time in the post-collapse region, estimated from our PT calculations. Our PT treatment combined with adaptive smoothing is illustrated in several cases. Predictions are compared to simulations and we find that post-collapse PT with adaptive smoothing reproduces the power spectrum and phase-space structures remarkably well even at small scales, where Zel'dovich solution substantially deviates from simulations.

  15. Impacts of vehicle exhaust black soot on germination of gram seed (Cicer arietinum L.

    Directory of Open Access Journals (Sweden)

    Naba Kumar Mondal

    2014-02-01

    Full Text Available An investigation was initiated to examine the effects of carbon soot collected from exhaust tube of 15 years old petrol and diesel operated vehicles on gram seed germination and biochemical changes of seedling. In view of the widespread cultivation of gram seed in India and long-term impact of black carbon is the warming of the atmosphere as per the recommendation of IPCC (2007. Black soot were separately treated with different doses and the effects of these treatment had on seed germination, seedling vigor, chlorophyll and carotenoid content, root and shoot growth, protein, sugar, phenol and proline estimation were studied. The treatment T6 significantly affected on seed germination (84% as well as seedling vigor and chlorophyll content. But other treatment promoted both seed germination and seedling vigor along with enhancement of other biochemical constituents. On the other hand micrograph study revealed that treatments T1 and T4 both showed negative effects on stomata rather than the ultra-structure of xylem and phloem.

  16. Acoustic anisotropic wavefields through perturbation theory

    KAUST Repository

    Alkhalifah, Tariq Ali

    2013-09-01

    Solving the anisotropic acoustic wave equation numerically using finite-difference methods introduces many problems and media restriction requirements, and it rarely contributes to the ability to resolve the anisotropy parameters. Among these restrictions are the inability to handle media with η<0 and the presence of shear-wave artifacts in the solution. Both limitations do not exist in the solution of the elliptical anisotropic acoustic wave equation. Using perturbation theory in developing the solution of the anisotropic acoustic wave equation allows direct access to the desired limitation-free solutions, that is, solutions perturbed from the elliptical anisotropic background medium. It also provides a platform for parameter estimation because of the ability to isolate the wavefield dependency on the perturbed anisotropy parameters. As a result, I derive partial differential equations that relate changes in the wavefield to perturbations in the anisotropy parameters. The solutions of the perturbation equations represented the coefficients of a Taylor-series-type expansion of the wavefield as a function of the perturbed parameter, which is in this case η or the tilt of the symmetry axis. The expansion with respect to the symmetry axis allows use of an acoustic transversely isotropic media with a vertical symmetry axis (VTI) kernel to estimate the background wavefield and the corresponding perturbation coefficients. The VTI extrapolation kernel is about one-fourth the cost of the transversely isotropic model with a tilt in the symmetry axis kernel. Thus, for a small symmetry axis tilt, the cost of migration using a first-order expansion can be reduced. The effectiveness of the approach was demonstrated on the Marmousi model.

  17. Genetics and Forest Seed Handling

    DEFF Research Database (Denmark)

    Schmidt, Lars Holger

    2016-01-01

    High genetic quality seed is obtained from seed sources that match the planting site, have a good outcrossing rate, and are superior in some desirable characters. Non-degraded natural forests and plantations may be used as untested seed sources, which can sometimes be managed to promote outbreeding...... and increase seed production. Planted seed orchards aim at capturing large genetic variation and are planted in a design that facilitates genetic evaluation and promotes outbred seed production. Good seed production relies upon success of the whole range of reproductive events from flower differentiation...

  18. Frugivores bias seed-adult tree associations through nonrandom seed dispersal: a phylogenetic approach.

    Science.gov (United States)

    Razafindratsima, Onja H; Dunham, Amy E

    2016-08-01

    Frugivores are the main seed dispersers in many ecosystems, such that behaviorally driven, nonrandom patterns of seed dispersal are a common process; but patterns are poorly understood. Characterizing these patterns may be essential for understanding spatial organization of fruiting trees and drivers of seed-dispersal limitation in biodiverse forests. To address this, we studied resulting spatial associations between dispersed seeds and adult tree neighbors in a diverse rainforest in Madagascar, using a temporal and phylogenetic approach. Data show that by using fruiting trees as seed-dispersal foci, frugivores bias seed dispersal under conspecific adults and under heterospecific trees that share dispersers and fruiting time with the dispersed species. Frugivore-mediated seed dispersal also resulted in nonrandom phylogenetic associations of dispersed seeds with their nearest adult neighbors, in nine out of the 16 months of our study. However, these nonrandom phylogenetic associations fluctuated unpredictably over time, ranging from clustered to overdispersed. The spatial and phylogenetic template of seed dispersal did not translate to similar patterns of association in adult tree neighborhoods, suggesting the importance of post-dispersal processes in structuring plant communities. Results suggest that frugivore-mediated seed dispersal is important for structuring early stages of plant-plant associations, setting the template for post-dispersal processes that influence ultimate patterns of plant recruitment. Importantly, if biased patterns of dispersal are common in other systems, frugivores may promote tree coexistence in biodiverse forests by limiting the frequency and diversity of heterospecific interactions of seeds they disperse. © 2016 by the Ecological Society of America.

  19. In vitro Seed-dressing Technique for the Control of Seed-borne ...

    African Journals Online (AJOL)

    In vitro Seed-dressing Technique for the Control of Seed-borne Fungi of Rice variety Faro -29. ... Journal of Applied Sciences and Environmental Management ... Fernasan-D, Apron Plus 50 DS and Dithane–M45), and soaking and slurry methods at various concentrations, for the control of seed-borne fungi of rice variety

  20. seed oils

    African Journals Online (AJOL)

    Timothy Ademakinwa

    processes, production of biodiesel, as lubricant and in deep-frying purposes. They could ... for its juice, nectars and fruit while its seeds are ... Malaysia. The fine seed powder was stored in a plastic container inside a refrigerator at between 4 o.

  1. Perturbations of higher-dimensional spacetimes

    Energy Technology Data Exchange (ETDEWEB)

    Durkee, Mark; Reall, Harvey S, E-mail: M.N.Durkee@damtp.cam.ac.uk, E-mail: H.S.Reall@damtp.cam.ac.uk [DAMTP, Centre for Mathematical Sciences, University of Cambridge, Wilberforce Road, Cambridge, CB3 0WA (United Kingdom)

    2011-02-07

    We discuss linearized gravitational perturbations of higher-dimensional spacetimes. For algebraically special spacetimes (e.g. Myers-Perry black holes), we show that there exist local gauge invariant quantities linear in the metric perturbation. These are the higher-dimensional generalizations of the 4D Newman-Penrose scalars that (in an algebraically special vacuum spacetime) satisfy decoupled equations of motion. We show that decoupling occurs in more than four dimensions if, and only if, the spacetime admits a null geodesic congruence with vanishing expansion, rotation and shear. Decoupling of electromagnetic perturbations occurs under the same conditions. Although these conditions are not satisfied in black hole spacetimes, they are satisfied in the near-horizon geometry of an extreme black hole.

  2. Application of linear and higher perturbation theory in reactor physics

    International Nuclear Information System (INIS)

    Woerner, D.

    1978-01-01

    For small perturbations in the material composition of a reactor according to the first approximation of perturbation theory the eigenvalue perturbation is proportional to the perturbation of the system. This assumption is true for the neutron flux not influenced by the perturbance. The two-dimensional code LINESTO developed for such problems in this paper on the basis of diffusion theory determines the relative change of the multiplication constant. For perturbations varying the neutron flux in the space of energy and position the eigenvalue perturbation is also influenced by this changed neutron flux. In such cases linear perturbation theory yields larger errors. Starting from the methods of calculus of variations there is additionally developed in this paper a perturbation method of calculation permitting in a quick and simple manner to assess the influence of flux perturbation on the eigenvalue perturbation. While the source of perturbations is evaluated in isotropic approximation of diffusion theory the associated inhomogeneous equation may be used to determine the flux perturbation by means of diffusion or transport theory. Possibilities of application and limitations of this method are studied in further systematic investigations on local perturbations. It is shown that with the integrated code system developed in this paper a number of local perturbations may be checked requiring little computing time. With it flux perturbations in first approximation and perturbations of the multiplication constant in second approximation can be evaluated. (orig./RW) [de

  3. Depth of dormancy in tomato seeds is related to the progression of the cell cycle prior to its induction

    NARCIS (Netherlands)

    Castro, de R.D.; Lammeren, van A.A.M.; Groot, S.P.C.; Bino, R.J.; Hilhorst, H.W.M.

    2001-01-01

    Cell cycle activities are initiated following imbibition of non-dormant seeds. However, it is not known whether cell cycle related events other than DNA replication also remain suppressed in imbibed dormant seeds. The objective of this study was to demonstrate that the transitions between the

  4. Comparisons of linear and nonlinear plasma response models for non-axisymmetric perturbations

    Energy Technology Data Exchange (ETDEWEB)

    Turnbull, A. D.; Ferraro, N. M.; Lao, L. L.; Lanctot, M. J. [General Atomics, P.O. Box 85608, San Diego, California 92186-5608 (United States); Izzo, V. A. [University of California-San Diego, 9500 Gilman Dr., La Jolla, California 92093-0417 (United States); Lazarus, E. A.; Hirshman, S. P. [Oak Ridge National Laboratory, P.O. Box 2008, Oak Ridge, Tennessee 37831 (United States); Park, J.-K.; Lazerson, S.; Reiman, A. [Princeton Plasma Physics Laboratory, P.O. Box 451, Princeton, New Jersey 08543-0451 (United States); Cooper, W. A. [Association Euratom-Confederation Suisse, Centre de Recherches en Physique des Plasmas, Ecole Polytechnique Federale de Lausanne, Lausanne (Switzerland); Liu, Y. Q. [Culham Centre for Fusion Energy, Culham Science Centre, Abingdon, Oxfordshire, OX14 3DB (United Kingdom); Turco, F. [Columbia University, 116th St and Broadway, New York, New York 10027 (United States)

    2013-05-15

    With the installation of non-axisymmetric coil systems on major tokamaks for the purpose of studying the prospects of ELM-free operation, understanding the plasma response to the applied fields is a crucial issue. Application of different response models, using standard tools, to DIII-D discharges with applied non-axisymmetric fields from internal coils, is shown to yield qualitatively different results. The plasma response can be treated as an initial value problem, following the system dynamically from an initial unperturbed state, or from a nearby perturbed equilibrium approach, and using both linear and nonlinear models [A. D. Turnbull, Nucl. Fusion 52, 054016 (2012)]. Criteria are discussed under which each of the approaches can yield a valid response. In the DIII-D cases studied, these criteria show a breakdown in the linear theory despite the small 10{sup −3} relative magnitude of the applied magnetic field perturbations in this case. For nonlinear dynamical evolution simulations to reach a saturated nonlinear steady state, appropriate damping mechanisms need to be provided for each normal mode comprising the response. Other issues arise in the technical construction of perturbed flux surfaces from a displacement and from the presence of near nullspace normal modes. For the nearby equilibrium approach, in the absence of a full 3D equilibrium reconstruction with a controlled comparison, constraints relating the 2D system profiles to the final profiles in the 3D system also need to be imposed to assure accessibility. The magnetic helicity profile has been proposed as an appropriate input to a 3D equilibrium calculation and tests of this show the anticipated qualitative behavior.

  5. 't Hooft loops and perturbation theory

    CERN Document Server

    De Forcrand, Philippe; Noth, D; Forcrand, Philippe de; Lucini, Biagio; Noth, David

    2005-01-01

    We show that high-temperature perturbation theory describes extremely well the area law of SU(N) spatial 't Hooft loops, or equivalently the tension of the interface between different Z_N vacua in the deconfined phase. For SU(2), the disagreement between Monte Carlo data and lattice perturbation theory for sigma(T)/T^2 is less than 2%, down to temperatures O(10) T_c. For SU(N), N>3, the ratios of interface tensions, (sigma_k/sigma_1)(T), agree with perturbation theory, which predicts tiny deviations from the ratio of Casimirs, down to nearly T_c. In contrast, individual tensions differ markedly from the perturbative expression. In all cases, the required precision Monte Carlo measurements are made possible by a simple but powerful modification of the 'snake' algorithm.

  6. Effect of Time and Burial Depth on Breaking Seed dormancy and Germination of Weed Seeds

    Directory of Open Access Journals (Sweden)

    marzie mazhari

    2016-02-01

    Full Text Available Introduction: Weeds limit crop growth, development and yield through competing. Seed bank of weeds in field is one of the sources which can affect weed management and their control methods. Environmental conditions during seed maturation and following dispersal interact to influence the germination phenology of many species. Disturbance plays a key role in the maintenance of habitat for many plant species, particularly referrals, for example, fire ephemerals, desert annuals, and arable weeds. Seed germination and emergence depend on endogenous and exogenous factors. Viable seeds are dormant when all environmental conditions are appropriate for germination but seeds fail to germinate. Thus, dormancy plays an important ecological role in preventing seed germination, being a major contributor to seed persistence of some species in soil. Buried seeds of annual weeds are certainly subjected to different soil moisture conditions during their dormancy release season (winter according to the annual rainfall pattern and burial depth. Shallow buried seeds are exposed to soil moisture fluctuations that could affect their dormancy status. Laboratory studies showed that desiccation and subsequent re-hydration of seeds could stimulate germination and modify seed light requirements. Seeds buried in deeper layers of the soil would not be exposed to such fluctuations in soil moisture, but would be exposed to different soil moisture environments depending on weather and soil characteristics. The effects of interactions between temperature, and soil or seed moisture, on seed dormancy changes have been reported for several species. Therefore, the objectives of this study were to determine the effect of time and burial depth treatments on seed germination and seedling emergence of Aegilops cylindrica, Agropyrom repens, Avena fatua, Bromus dantoniae, Cynodon dactylon, Cyprus rotundus, Setaria viridis, Anthriscus sylvestris, Centurea cyanus. Materials and Methods: In

  7. Morphology-controlled synthesis of silver nanostructures via a seed catalysis process

    Energy Technology Data Exchange (ETDEWEB)

    Chen Chang; Wang Li; Yu Haojie; Wang Jianjun; Zhou Junfeng; Tan Qiaohua; Deng Libo [State Key Laboratory of Polymer Reaction Engineering, Zhejiang University, Hangzhou 310027 (China)

    2007-03-21

    A novel, effective strategy named 'seed catalysis' has been described here to synthesize silver nanostructures with controllable morphology. Typically, we added Na{sub 2}S into the reaction system and the Ag{sub 2}S semiconductor colloids formed at the initial stage would act as both seeds and catalyst in the silver reduction. The morphology of products is controlled by the concentration of Na{sub 2}S added to the system. Low concentration of Na{sub 2}S gives nanocubes of 40-50 nm in size, while a high concentration of Na{sub 2}S is of benefit to obtain nanowires. The growth of the silver crystal is also accelerated by the catalysis of Ag{sub 2}S. Electron microscopy and UV-vis absorption spectra have been used to investigate the evolution of silver nanowires, and a reasonable mechanism to explain the role of Ag{sub 2}S seeds has also been suggested. This semiconductor seed catalysis strategy will provide wide applications in the fabrication of metal nanomaterials.

  8. Effects of Polyphenols from Grape Seeds on Renal Lithiasis

    Directory of Open Access Journals (Sweden)

    Felix Grases

    2015-01-01

    Full Text Available Nephrolithiasis is a complex disease that results from a combination of factors related to both urine composition and kidney morphoanatomy. Development of calcium oxalate monohydrate papillary calculi is linked to initial subepithelial calcification of renal papilla. Progressive tissue calcification depends on preexisting injury and involves reactive oxygen species. Many plant extracts that protect against oxidative stress manifest antilithiasic activity. Our study focused on determining the effects of polyphenols on a lithiasis rat model. Rats were pretreated with polyphenols and grape seed extracts, followed by posterior induction of hyperoxalosis via treatment with ethylene glycol plus NH4Cl. The concentrations of calcium and other elements in kidney were determined, along with histological examination of kidney and 24 h urine analysis. Significant differences were observed in the renal calcium content between the control plus ethylene glycol-treated group and the epicatechin plus ethylene glycol-treated, red grape seed extract plus ethylene glycol-treated, and white grape seed extract plus ethylene glycol-treated groups, with reductions of about 50%. The antioxidant activity of polyphenols extracted from red and white grape seeds may be critical in the prevention of calcium oxalate monohydrate papillary calculus formation, particularly if calculi are induced by lesions caused by cytotoxic compounds with oxidative capacity.

  9. Propagation of Ion Acoustic Perturbations

    DEFF Research Database (Denmark)

    Pécseli, Hans

    1975-01-01

    Equations describing the propagation of ion acoustic perturbations are considered, using the assumption that the electrons are Boltzman distributed and isothermal at all times. Quasi-neutrality is also considered.......Equations describing the propagation of ion acoustic perturbations are considered, using the assumption that the electrons are Boltzman distributed and isothermal at all times. Quasi-neutrality is also considered....

  10. Multivariate NIR studies of seed-water interaction in Scots Pine Seeds (Pinus sylvestris L.)

    OpenAIRE

    Lestander, Torbjörn

    2003-01-01

    This thesis describes seed-water interaction using near infrared (NIR) spectroscopy, multivariate regression models and Scots pine seeds. The presented research covers classification of seed viability, prediction of seed moisture content, selection of NIR wavelengths and interpretation of seed-water interaction modelled and analysed by principal component analysis, ordinary least squares (OLS), partial least squares (PLS), bi-orthogonal least squares (BPLS) and genetic algorithms. The potenti...

  11. The importance of using certified seed

    OpenAIRE

    Bogdanović Sandra; Mladenov Velimir; Balešević-Tubić Svetlana

    2015-01-01

    Certified seed is produced from the seed of known genetic origin and genetic purity with controlled and tested production, processed and declared in accordance with the Law on Seeds. Production of certified seed is carried out under the supervision of the Ministry of Agriculture and Environmental Protection, by seed producers formally listed in the Seed Register. Seed is processed in registered seed processing centres and quality is tested in laboratories accredited for seed testing. The orga...

  12. Experimental characterization of initial conditions and spatio-temporal evolution of a small Atwood number Rayleigh-Taylor mixing layer

    Energy Technology Data Exchange (ETDEWEB)

    Mueschke, N J; Andrews, M J; Schilling, O

    2005-09-26

    The initial multi-mode interfacial velocity and density perturbations present at the onset of a small Atwood number, incompressible, miscible, Rayleigh-Taylor instability-driven mixing layer have been quantified using a combination of experimental techniques. The streamwise interfacial and spanwise interfacial perturbations were measured using high-resolution thermocouples and planar laser-induced fluorescence (PLIF), respectively. The initial multi-mode streamwise velocity perturbations at the two-fluid density interface were measured using particle-image velocimetry (PIV). It was found that the measured initial conditions describe an initially anisotropic state, in which the perturbations in the streamwise and spanwise directions are independent of one another. The evolution of various fluctuating velocity and density statistics, together with velocity and density variance spectra, were measured using PIV and high-resolution thermocouple data. The evolution of the velocity and density statistics is used to investigate the early-time evolution and the onset of strongly-nonlinear, transitional dynamics within the mixing layer. The early-time evolution of the density and vertical velocity variance spectra indicate that velocity fluctuations are the dominant mechanism driving the instability development. The implications of the present experimental measurements on the initialization of Reynolds-averaged turbulent transport and mixing models and of direct and large-eddy simulations of Rayleigh-Taylor instability-induced turbulence are discussed.

  13. seed flour

    African Journals Online (AJOL)

    ONOS

    2010-09-06

    Sep 6, 2010 ... and with a nice taste, used for cooking or as lamp oil. The fatty acid ... Pra seeds were obtained from a local market in Nakhon Si Thammarat. Page 2. Table 1. Proximate composition of pra seed flour. Constituent. Percentage ...

  14. Defining the role of fire in alleviating seed dormancy in a rare Mediterranean endemic subshrub.

    Science.gov (United States)

    Cross, Adam T; Paniw, Maria; Ojeda, Fernando; Turner, Shane R; Dixon, Kingsley W; Merritt, David J

    2017-09-01

    Fire is a topical issue in the management of many ecosystems globally that face a drying climate. Understanding the role of fire in such ecosystems is critical to inform appropriate management practices, particularly in the case of rare and ecologically specialized species. The Mediterranean heathlands are highly fire-prone and occur in a biodiversity hotspot increasingly threatened by human activities, and determining the reproductive thresholds of at-risk heathland species is critical to ensuring the success of future conservation initiatives. This study examined the germination biology of the threatened carnivorous subshrub Drosophyllum lusitanicum , with specific focus on the role of fire-related cues (heat and smoke) in combination with seasonal temperatures and moisture conditions to determine how these factors regulate seed dormancy and germination. We found that D. lusitanicum produces water-permeable, physiologically dormant seeds with a fully developed, capitate embryo that when fresh (~1 month old) and without treatment germinate to 20-40 % within 4-8 weeks. Seeds possess a restricted thermal window (15-20 °C) for germination and a neutral photoblastic response. Seed dormancy was overcome through precision nicking of the seed coat (>90 % germination) or by short exposure to dry heat (80 or 100 °C) for 5-30 min (60-100 % germination). We propose seedling emergence from the soil seed bank may be cued by the passage of fire, or by soil disturbance from the movement and browsing of animals. Long-term population viability is likely to be contingent upon appropriate management of the persistent soil seed bank, as well as the adequate management of key ecological disturbances such as fire. Drosophyllum lusitanicum faces an increasingly bleak future in the absence of conservation and management initiatives aimed at reducing habitat fragmentation in heathlands and aligning fire management and livestock practices with biodiversity outcomes.

  15. Nonsingular cosmology with a scale-invariant spectrum of cosmological perturbations from Lee-Wick theory

    International Nuclear Information System (INIS)

    Cai Yifu; Qiu Taotao; Brandenberger, Robert; Zhang Xinmin

    2009-01-01

    We study the cosmology of a Lee-Wick type scalar field theory. First, we consider homogeneous and isotropic background solutions and find that they are nonsingular, leading to cosmological bounces. Next, we analyze the spectrum of cosmological perturbations which result from this model. Unless either the potential of the Lee-Wick theory or the initial conditions are finely tuned, it is impossible to obtain background solutions which have a sufficiently long period of inflation after the bounce. More interestingly, however, we find that in the generic noninflationary bouncing cosmology, perturbations created from quantum vacuum fluctuations in the contracting phase have the correct form to lead to a scale-invariant spectrum of metric inhomogeneities in the expanding phase. Since the background is nonsingular, the evolution of the fluctuations is defined unambiguously through the bounce. We also analyze the evolution of fluctuations which emerge from thermal initial conditions in the contracting phase. The spectrum of gravitational waves stemming from quantum vacuum fluctuations in the contracting phase is also scale-invariant, and the tensor to scalar ratio is not suppressed.

  16. Perturbation methods for power and reactivity reconstruction

    International Nuclear Information System (INIS)

    Palmiotti, G.; Salvatores, M.; Estiot, J.C.; Broccoli, U.; Bruna, G.; Gomit, J.M.

    1987-01-01

    This paper deals with recent developments and applications in perturbation methods. Two types of methods are used. The first one is an explicit method, which allows the explicit reconstruction of a perturbed flux using a linear combination of a library of functions. In our application, these functions are the harmonics (i.e. the high order eigenfunctions of the system). The second type is based on the Generalized Perturbation Theory GPT and needs the calculation of an importance function for each integral parameter of interest. Recent developments of a particularly useful high order formulation allows to obtain satisfactory results also for very large perturbations

  17. On adiabatic perturbations in the ekpyrotic scenario

    International Nuclear Information System (INIS)

    Linde, A.; Mukhanov, V.; Vikman, A.

    2010-01-01

    In a recent paper, Khoury and Steinhardt proposed a way to generate adiabatic cosmological perturbations with a nearly flat spectrum in a contracting Universe. To produce these perturbations they used a regime in which the equation of state exponentially rapidly changed during a short time interval. Leaving aside the singularity problem and the difficult question about the possibility to transmit these perturbations from a contracting Universe to the expanding phase, we will show that the methods used in Khoury are inapplicable for the description of the cosmological evolution and of the process of generation of perturbations in this scenario

  18. Scientific designs of pine seeds and pine cones for species conservation

    Science.gov (United States)

    Song, Kahye; Yeom, Eunseop; Kim, Hyejeong; Lee, Sang Joon

    2015-11-01

    Reproduction and propagation of species are the most important missions of every living organism. For effective species propagation, pine cones fold their scales under wet condition to prevent seeds from short-distance dispersal. They open and release their embedded seeds on dry and windy days. In this study, the micro-/macro-scale structural characteristics of pine cones and pine seeds are studied using various imaging modalities. Since the scales of pine cones consist of dead cells, the folding motion is deeply related to structural changes. The scales of pine cones consist of three layers. Among them, bract scales are only involved in collecting water. This makes pine cones reduce the amount of water and minimize the time spent on structural changes. These systems also involve in drying and recovery of pine cones. In addition, pine cones and pine seeds have advantageous structures for long-distance dispersal and response to natural disaster. Owing to these structural features, pine seeds can be released safely and efficiently, and these types of structural advantages could be mimicked for practical applications. This research was financially supported by the Creative Research Initiative of the Ministry of Science, ICT and Future Planning (MSIP) and the National Research Foundation (NRF) of Korea (Contract grant number: 2008-0061991).

  19. Why high seed densities within buried mesh bags may overestimate depletion rates of soil seed banks

    NARCIS (Netherlands)

    Mourik, van T.A.; Stomph, T.J.; Murdoch, A.J.

    2005-01-01

    1. Estimates of seed bank depletion rates are essential for modelling and management of plant populations. The seed bag burial method is often used to measure seed mortality in the soil. However, the density of seeds within seed bags is higher than densities in natural seed banks, which may elevate

  20. ANALYSIS OF PERTURBED MOTION STABILITY OF WHEELER VEHICLES BRAKES CONTROL SYSTEM

    Directory of Open Access Journals (Sweden)

    V. Verbytskiyi

    2011-01-01

    Full Text Available The analysis of the perturbed motion stability of the brake automatic control system on the basis of Lyapunov’s second method is carried out. Using transformations of Lurie there has been ob-tained the canonical form of the system of equations of automatic control. It allowed determining the necessary and sufficient conditions of the asymptotic stability of the system irrespective of its initial condition and a definite choice of the admissible characteristic of the regulator.