563 research outputs found

    Relationships between climate and winter cereal grain quality in Finland and their potential for forecasting

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    Many studies have demonstrated the effects of climate on cereal yield, but there has been little work carried out examining the relationships between climate and cereal grain quality on a national scale. In this study national mean hectolitre weight for both rye and winter wheat in Finland was modelled using monthly gridded accumulated snow depth, precipitation rate, solar radiation and temperature over the period 1971 to 2001. Variables with significant relationships in correlation analysis both before and after difference detrending were further investigated using forward stepwise regression. For rye, March snow depth, and June and July solar radiation accounted for 66% of the year-to-year variance in hectolitre weight, and for winter wheat January snow depth, June solar radiation and August temperature accounted for 62% of the interannual variance in hectolitre weight. Further analysis of national variety trials and weather station data was used to support proposed biological mechanisms. Finally a cross validation technique was used to test forecast models with those variables available by early July by making predictions of above or below the mean hectolitre weight. Analysis of the contingency tables for these predictions indicated that national hectolitre weight forecasts are feasible for both cereals in advance of harvest

    Chiral Condensates in Quark and nuclear Matter

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    We present a novel treatment for calculating the in-medium quark condensates. The advantage of this approach is that one does not need to make further assumptions on the derivatives of model parameters with respect to the quark current mass. The normally accepted model-independent result in nuclear matter is naturally reproduced. The change of the quark condensate induced by interactions depends on the incompressibility of nuclear matter. When it is greater than 260 MeV, the density at which the condensate vanishes is higher than that from the linear extrapolation. For the chiral condensate in quark matter, a similar model-independent linear behavior is found at lower densities, which means that the decreasing speed of the condensate in quark matter is merely half of that in nuclear matter if the pion-nucleon sigma commutator is six times the average current mass of u and d quarks. The modification due to QCD-like interactions is found to slow the decreasing speed of the condensate, compared with the linear extrapolation.Comment: 12 pages, 7 figures, revtex4 styl

    Constraints on the three-fluid model of curvaton decay

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    A three fluid system describing the decay of the curvaton is studied by numerical and analytical means. We place constraints on the allowed interaction strengths between the fluids and initial curvaton density by requiring that the curvaton decays before nucleosynthesis while nucleosynthesis, radiation-matter equality and decoupling occur at correct temperatures. We find that with a continuous, time-independent interaction, a small initial curvaton density is naturally preferred along with a low reheating temperature. Allowing for a time-dependent interaction, this constraint can be relaxed. In both cases, a purely adiabatic final state can be generated, but not without fine-tuning. Unlike in the two fluid system, the time-dependent interactions are found to have a small effect on the curvature perturbation itself due to the different nature of the system. The presence of non-gaussianity in the model is discussed.Comment: 9 pages, 10 figure

    Neutrino Fluxes from CMSSM LSP Annihilations in the Sun

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    We evaluate the neutrino fluxes to be expected from neutralino LSP annihilations inside the Sun, within the minimal supersymmetric extension of the Standard Model with supersymmetry-breaking scalar and gaugino masses constrained to be universal at the GUT scale (the CMSSM). We find that there are large regions of typical CMSSM (m1/2,m0)(m_{1/2}, m_0) planes where the LSP density inside the Sun is not in equilibrium, so that the annihilation rate may be far below the capture rate. We show that neutrino fluxes are dependent on the solar model at the 20% level, and adopt the AGSS09 model of Serenelli et al. for our detailed studies. We find that there are large regions of the CMSSM (m1/2,m0)(m_{1/2}, m_0) planes where the capture rate is not dominated by spin-dependent LSP-proton scattering, e.g., at large m1/2m_{1/2} along the CMSSM coannihilation strip. We calculate neutrino fluxes above various threshold energies for points along the coannihilation/rapid-annihilation and focus-point strips where the CMSSM yields the correct cosmological relic density for tan(beta) = 10 and 55 for ÎĽ\mu > 0, exploring their sensitivities to uncertainties in the spin-dependent and -independent scattering matrix elements. We also present detailed neutrino spectra for four benchmark models that illustrate generic possibilities within the CMSSM. Scanning the cosmologically-favored parts of the parameter space of the CMSSM, we find that the IceCube/DeepCore detector can probe at best only parts of this parameter space, notably the focus-point region and possibly also at the low-mass tip of the coannihilation strip.Comment: 32 pages, 13 figures. v2: updated/expanded discussion of IceCube/DeepCor

    Using multiple imputation and intervention-based scenarios to project the mobility of older adults

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    Background: Projections of the development of mobility limitations of older adults are needed for evidence-based policy making. The aim of this study was to generate projections of mobility limitations among older people in the United States, England, and Finland. Methods: We applied multiple imputation modelling with bootstrapping to generate projections of stair climbing and walking limitations until 2026. A physical activity intervention producing a beneficial effect on self-reported activities of daily living measures was identified in a comprehensive literature search and incorporated in the scenarios used in the projections. We utilised the harmonised longitudinal survey data from the Ageing Trajectories of Health – Longitudinal Opportunities and Synergies (ATHLOS) project (N = 24,982). Results: Based on the scenarios from 2012 to 2026, the prevalence of walking limitations will decrease from 9.4 to 6.4%. A physical activity intervention would decrease the prevalence of stair climbing limitations compared with no intervention from 28.9 to 18.9% between 2012 and 2026. Conclusions: A physical activity intervention implemented on older population seems to have a positive effect on maintaining mobility in the future. Our method provides an interesting option for generating projections by incorporating intervention-based scenarios

    PyCOOL - a Cosmological Object-Oriented Lattice code written in Python

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    There are a number of different phenomena in the early universe that have to be studied numerically with lattice simulations. This paper presents a graphics processing unit (GPU) accelerated Python program called PyCOOL that solves the evolution of scalar fields in a lattice with very precise symplectic integrators. The program has been written with the intention to hit a sweet spot of speed, accuracy and user friendliness. This has been achieved by using the Python language with the PyCUDA interface to make a program that is easy to adapt to different scalar field models. In this paper we derive the symplectic dynamics that govern the evolution of the system and then present the implementation of the program in Python and PyCUDA. The functionality of the program is tested in a chaotic inflation preheating model, a single field oscillon case and in a supersymmetric curvaton model which leads to Q-ball production. We have also compared the performance of a consumer graphics card to a professional Tesla compute card in these simulations. We find that the program is not only accurate but also very fast. To further increase the usefulness of the program we have equipped it with numerous post-processing functions that provide useful information about the cosmological model. These include various spectra and statistics of the fields. The program can be additionally used to calculate the generated curvature perturbation. The program is publicly available under GNU General Public License at https://github.com/jtksai/PyCOOL . Some additional information can be found from http://www.physics.utu.fi/tiedostot/theory/particlecosmology/pycool/ .Comment: 23 pages, 12 figures; some typos correcte

    On the estimate of the sigma^(I = 1)_(KN)(0)-term value from the energy level shift of kaonic hydrogen in the ground state

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    Using the experimental data on the energy level shift of kaonic hydrogen in the ground state (the DEAR Collaboration, Phys. Rev. Lett. 94, 212302 (2005)) and the theoretical value of the energy level shift, calculated within the phenomenological quantum field theoretic approach to the description of strong low-energy anti-K N and anti-K NN interactions developed at Stefan Meyer Institut fuer subatomare Physik in Vienna, we estimate the value of the sigma^(I = 1)_(KN)(0)-term of low-energy anti-K N scattering. We get sigma^(I = 1)_(KN)(0) = (433 +/- 85) MeV. This testifies the absence of strange quarks in the proton structure.Comment: 7 pages, no figure
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