Search results for "Theoretical models"
showing 10 items of 79 documents
Microcalorimeter/EBIT measurements of X-ray spectra of highly charged ions
2001
Spectra of highly charged Ar, Kr, Xe and Fe ions, produced in an Electron Beam Ion Trap (EBIT), have been recorded in a broad X-ray energy band (0.2 keV to 10 keV) with a microcalorimeter detector. The first analysis of the Kr spectra has been completed and most of the spectral lines have been identified as transitions of B- to Al-like Kr. Line intensity ratios of Fe XVII have been measured and compared with theoretical models.
Hydrodynamic chromatography of macromolecules on 2 μm non-porous spherical silica gel packings
1989
Non-porous spherical 2μm silica gel particles have been tested as packing for hydrodynamic chromatography of macromolecules (HDC). Columns packed with these particles in 250×4.6mm i.d. columns can be operated very efficiently (e.g. a reduced plate height of about 2) when the detection cell is miniaturized. The packing is suitable for the separation of polystyrenes of Mw of 104–107 by hydrodynamic chromatography and the retention behaviour of polystyrenes agrees well with the known theoretical models. Preliminary results on the applicability of HDC for the separation of biopolymers are presented.
Numerical Simulations of Jets from Active Galactic Nuclei
2019
Numerical simulations have been playing a crucial role in the understanding of jets from active galactic nuclei (AGN) since the advent of the first theoretical models for the inflation of giant double radio galaxies by continuous injection in the late 1970s. In the almost four decades of numerical jet research, the complexity and physical detail of simulations, based mainly on a hydrodynamical/magneto-hydrodynamical description of the jet plasma, have been increasing with the pace of the advance in theoretical models, computational tools and numerical methods. The present review summarizes the status of the numerical simulations of jets from AGNs, from the formation region in the neighborho…
Observation of the decay KL → πoγγ and of a form factor enhancement in the decay KL → e+e−γ
1991
Abstract The rare decay mode K L → o γγ has been observed in an experiment of the NA31 collaboration at CERN. From a signal of 21 events with a background of 1.5 ± 0.9 events, a branching ratio of (2.1 ± 0.6)10 −6 is calculated for decays with an invariant γγ mass above 280 MeV. This result is compared with the values estimated from theoretical models and has implications for the CP-conserving contribution to K L → π o e + e − decay. In the same experiment, 1053 decays of the type K L → e + e − γ were observed. The branching ratio is measured to be (9.2 ± 0.5 ± 0.5)10 −6 in good agreement with theoretical expectations. An enhancement is observed at high masses in the distribution of the inv…
Sex-role orientation and memory for gender-related terms: Another uncertain link
1989
Two studies are reported which investigate the relationship between sex-role orientation and memory for gender-related terms. Based on the concept of ‘cognitive schema’, theoretical models have recently been advanced suggesting that the schematic cognitive representation of gender facilitates the recall of words pertinent to gender. One of these models, Markus' self-schema theory, proposes that masculine and feminine sex-typed individuals have a better memory for terms that correspond to their respective self-schemata. In contrast, Bem's gender schema theory implies that sex-typed individuals have a better memory for the category of gender as a whole, i.e. for both masculine and feminine te…
Threshold cointegration and nonlinear adjustment between stock prices and dividends
2008
According to several empirical studies, the linear present-value model fails to explain the behaviour of stock prices in the long run. We analyse the possible presence of threshold cointegration between real stock prices and dividends for the US market during the period from 1871:1 to 2004:6. According to our results, the null hypothesis of linear cointegration between stock prices and dividends is rejected in favour of a two-regime threshold cointegration model. We find also that stock prices do not respond to equilibrium error, and dividends respond to the past divergence only if the deviation from the equilibrium error does not exceed the estimated threshold parameter. This in turn would…
The diffusion and influence of theoretical models of information behaviour : the case of Savolainen's ELIS model
2020
PurposeTo ascertain the diffusion and influence of Savolainen's ELIS model and its use as a theoretical and/or methodological basis for research.Design/methodology/approachA context citation analysis was made of the work where this researcher published his model. Analysis covered the year of publication, the type of work and the subject matter of the citing documents concerned. In-context citations were analysed for their frequency in each citing text, style, location and content cited.FindingsThe ELIS model received 18.5 cites/year. 20.2 per cent of them corresponded to papers published in journals in other areas, mainly computer science. The average of cites per paper was 1.8; 64.5 percen…
Exotic hyperons: Theoretical status and search perspectives in hyperon beam facilities
1992
The theoretical models that predict the existence of exotic hyperons made of more than three quarks are reviewed. We present the properties of exotic hyperons with strangenessS=−1 (quark contents $$sqqq\bar q$$ ),S=−2 ( $$ssqq\bar q$$ ) andS=−3 ( $$sssq\bar q$$ ) predicted by the sum rules for reggeon-particle scattering amplitudes. The inclusive cross sections for the production of these hyperons in hyperon-proton interactions are calculated. The cross sections turn out to be of the order of millibarns, thus opening a good perspective to encounter such exotic hyperons in the available hyperon beam facilities at CERN and FNAL. We also propose to study the Regge trajectories corresponding to…
Learning processes in user training
2010
While the maturing research literature on training has generated increasingly sophisticated and more comprehensive theoretical models, the actual process through which users learn to use a system remains a relatively neglected area. The extant literature that has paid attention to processes have conceptualized these as structures and examined them through variance studies. In this paper, we address this knowledge gap by advancing hermeneutics as a lens to depict the process through which users come to learn about the system. We explain the hermeneutic process, situate it in a training context and illustrate our conceptualization by interpreting a specific training program at a large organiz…
Intrinsic volatility of synaptic connections — a challenge to the synaptic trace theory of memory
2017
According to the synaptic trace theory of memory, activity-induced changes in the pattern of synaptic connections underlie the storage of information for long periods. In this framework, the stability of memory critically depends on the stability of the underlying synaptic connections. Surprisingly however, synaptic connections in the living brain are highly volatile, which poses a fundamental challenge to the synaptic trace theory. Here we review recent experimental evidence that link the initial formation of a memory with changes in the pattern of connectivity, but also evidence that synaptic connections are considerably volatile even in the absence of learning. Then we consider different…