The results obtained at the BGO-OD experiment with the BGO calorimeter, equipped with the new electronic readout based on sampling ADCs, during the tests performed with the beam time of March and ...June 2012 are presented. The proper functioning of the apparatus has allowed the reconstruction of the pseudo-scalar mesons π0 and η invariant masses. The simulation of the η' photoproduction reaction prepared for a proposal to the joint ELSA-MAMI Physics Advisory Committee is also presented.
Given a population dynamics model and a sufficiently long time series of data, the model parameters can be measured in different segments of this series to get respectively different estimates and a ...model with time-variable parameters. The variations in model parameters can be caused either by variations in the environmental conditions which affect population size, or by mere demographic stochasticity. As an example, a possible approach to the issue is considered for the data on fluctuations in the population density of pine moth (Bupalus piniarius L.) in Germany. To approximate the data, the well-known Moran-Ricker model is used, which has a rich variety of dynamic regimes. Parameter estimation was carried out by the least squares method (along 12 out of 58 values). The analysis of trends in the two series of model coefficients--the maximal growth rate and the coefficient of self-regulation--reveals that the changes in both indexes are low for quite a long period of time (60 years), and the hypothesis of no directed trends in the environment changes turns out statistically plausible.
The ELISe project, which is an integral part of the development of FAIR – Facility for Antiproton and Ion Research (FAIR, Darmstadt, Germany), is a project for developing the first accelerator in the ...world with colliding beams that uses the latest accelerator technology and experimental techniques. The ELISe experimental facility makes it possible to conduct a wide class of experiments using different nuclear reactions and thereby to study the diverse problems of nuclear physics and nuclear reactions. The experiments on electron scattering by nuclei far from the valley of stability will yield unique information on the distribution of charge in nuclei and the transitional density in nuclear excitations as well as single particle and cluster systems.
Four population dynamics models, namely Verhulst, Gompertz, Rosenzweig, and Svirezhev ones, have been used to approximate two well-known time-series of Paramecia aurelia and P. caudatum population ...size (Gause, 1934). The parameters are estimated for each of the models by the least-square method (with global fitting) in two different ways: with and without an additional upper bound for a parameter value. In the latter (traditional) case, when the deviations of theoretical (model) trajectories from experimental time-series have been tested for normality (Kolmogorov-Smirnov test, Shapiro-Wilk test) with zero average, and for the presence/absence of serial correlations (Durbin-Watson criteria), the best results are obtained for the Gompertz and Verhulst models. In the former, more realistic, case (when we impose an additional constraint that the parameter meaning the carrying capacity of the environment has to be greater than any element in the sample), the best results are observed for the Gompertz model. Under this constraint, the canonical technique for deviation analysis can be applied in a restricted version only.
Abstract The differential cross section for the quasi-free photoproduction reaction $$\gamma n\rightarrow K^0\Sigma ^0$$ γ n → K 0 Σ 0 was measured at BGOOD at ELSA from threshold to a centre-of-mass ...energy of $$2400\,\hbox {MeV}$$ 2400 MeV . Close to threshold the results are consistent with existing data and are in agreement with partial wave analysis solutions over the full measured energy range, with a large coupling to the $$\Delta (1900)1/2^-$$ Δ ( 1900 ) 1 / 2 - evident. This is the first dataset covering the $$K^*$$ K ∗ threshold region, where there are model predictions of dynamically generated vector meson-baryon resonance contributions.
A brief review of the works devoted to studying the photonuclear reactions near the threshold at the LUE-8.5 MeV linear electron accelerator of the Institute for Nuclear Research of the Russian ...Academy of Sciences and the terawatt femtosecond laser complex of the International Laser Center at Moscow State University is provided. The main focus of attention is the simulation of the experiments using the GEANT-4 code. This allowed us to compare the possibilities of different methods and determine the main directions of future research.
The Lotka–Volterra model was applied to the population densities of diamondback moth (DBM),
Plutella xylostella (L.) and its exotic larval parasitoid
Diadegma semiclausum (Hellen) data that was ...collected earlier by
icipe's DBM biological control team. The collections were done for 15 months before the release and 36 months after release of the parasitoid in two areas; in Werugha, Coast Province of Kenya and Tharuni, Central Province of Kenya, respectively. For each area in pre- and post-release periods, we estimated Lotka–Volterra model parameters from the minimization of the loss function between the theoretical and experimental time-series datasets following the Nelder-Mead multidimensional method. The model estimated a reduction in the value of the steady state of DBM population from 4.86 to 2.17 in Werugha and from 6.11 to 3.76 and 3.45 (with and without exclusion of the time before
D. semiclausum recovery) in Tharuni when transiting from the pre- and post-release periods, respectively. This change was a consequence of the newly introduced parasitoid, in the areas. The study presented a successful and detailed technique for non-linear model parameters restoration which was demonstrated by the correct mimicking of empirical datasets from the classical biological control with
D. semiclausum, in different areas of Kenya. The applied model has measured the parasitoids impact on the DBM biological control through a quantitative estimate of the effectiveness of the newly introduced species
D. semiclausum. These equations may therefore be used as tool for decision making in the implementation for such pests’ management system strategy.
In this article, we describe an experimental verification of the correctness of registration of delayed neutrons from .sup.238U photofission at a maximum energy of 10 MeV of bremsstrahlung gamma ...quanta on a pulsed linear electron accelerator LUE-8-5 in an interval of (1-5) ms after each beam pulse at times greater-than or equivalent to7 min from the onset of irradiation. The measurements have been carried out using the scintillation spectrometer of fast neutrons based on a single stilbene crystal with pulse shape discrimination of gamma quanta and fast neutrons. The temporal dependence of the counting rate of delayed neutrons in .sup.238U photofission has been measured at a repetition rate of 300 s.sup.-1 in a time interval of (1.25-3.30) ms after the beam pulse.
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