Long-term IR Photometry of Seyferts

Long-term (up to 10000d) monitoring has been undertaken for 41 Seyferts in the near-IR (JHKL). All but 2 showed variability, with K ampl in the range <0.1 to > 1.1 mags. The timescale for detectable change is from about one week to a few years. A simple cross-correlation study shows evidence for delays of up to several hundred days between the variations seen at the shortest wavelengths and the longest in many galaxies. In particular, the data for F9 now extend to twice the interval covered earlier and the delay between its UV and IR outputs persists. An analysis of the fluxes shows that, for any given galaxy, the colours of the variable component are usually independent of the level of activity. The state of activity can be parameterized. Taken over the whole sample, the colours of the variable components fall within moderately narrowly defined ranges. In particular, the H-K colour is appropriate to a black body of temperature 1600K. The H-K excess for a heavily reddened nucleus can be determined and used to find E_{B-V}, which can be compared to the values found from the visible region broad line fluxes. Using flux-flux diagrams, the flux within the aperture from the underlying galaxy can often be determined without the need for model surface brightness profiles. In many galaxies it is apparent that here must be an additional constant contribution from warm dust.Comment: Better quality available from ftp://ftp.saao.ac.za/pub/isg/seyf.pd

Fast-neutron induced pre-equilibrium reactions on 55Mn and 63,65Cu at energies up to 40 MeV

Excitation functions were measured for the $^{55}$Mn(n,2n)$^{54}$Mn, $^{55}$Mn(n,$\alpha$)$^{52}$V, $^{63}$Cu(n,$\alpha$)$^{60}$Co, $^{65}$Cu(n,2n)$^{64}$Cu, and $^{65}$Cu(n,p)$^{65}$Ni reactions from 13.47 to 14.83 MeV. The experimental cross sections are compared with the results of calculations including all activation channels for the stable isotopes of Mn and Cu, for neutron incident energies up to 50 MeV. Within the energy range up to 20 MeV the model calculations are most sensitive to the parameters related to nuclei in the early stages of the reaction, while the model assumptions are better established by analysis of the data in the energy range 20-40 MeV. While the present analysis has taken advantage of both a new set of accurate measured cross sections around 14 MeV and the larger data basis fortunately available between 20 and 40 MeV for the Mn and Cu isotopes, the need of additional measurements below as well as above 40 MeV is pointed out. Keywords: 55Mn, 63,65Cu, E$\leq$40 MeV, Neutron activation cross section measurements, Nuclear reactions, Model calculations, Manganese, CopperComment: 39 pages, 12 figure

Multiwavelength observations of short time-scale variability in NGC 4151. I. Ultraviolet observations

We present the results of an intensive ultraviolet monitoring campaign on the Seyfert 1 galaxy NGC 4151, as part of an effort to study its short time-scale variability over a broad range in wavelength. The nucleus of NGC 4151 was observed continuously with the {\it International Ultraviolet Explorer} (IUE) for 9.3 days, yielding a pair of LWP and SWP spectra every $\sim$70 minutes, and during four-hour periods for 4 days prior to and 5 days after the continuous monitoring period. The sampling frequency of the observations is an order of magnitude higher than that of any previous UV monitoring campaign on a Seyfert galaxy. The continuum fluxes in bands from 1275 \AA\ to 2688 \AA\ went through four significant and well-defined ``events'' of duration 2 -- 3 days during the continuous monitoring period. We find that the amplitudes of the continuum variations decrease with increasing wavelength, which extends a general trend for this and other Seyfert galaxies to smaller time scales (i.e., a few days). The continuum variations in all of the UV bands are {\it simultaneous} to within an accuracy of about 0.15 days, providing a strict constraint on continuum models. The emission-line light curves show only one major event during the continuous monitoring (a slow rise followed by a shallow dip), and do not correlate well with continuum light curves over the (short) duration of the campaign, because the time scale for continuum variations is apparently smaller than the response times of the emission lines.Comment: 39 pages, LaTeX, including 7 PostScript figures; To appear in the ApJ (October 20, 1996) Vol. 47

Multiwavelength observations of short time-scale variability in NGC 4151. IV. Analysis of multiwavelength continuum variability

This paper combines data from the three preceding papers in order to analyze the multi-waveband variability and spectral energy distribution of the Seyfert~1 galaxy NGC~4151 during the December 1993 monitoring campaign. The source, which was near its peak historical brightness, showed strong, correlated variability at X-ray, ultraviolet, and optical wavelengths. The strongest variations were seen in medium energy ($\sim$1.5~keV) X-rays, with a normalized variability amplitude (NVA) of 24\%. Weaker (NVA = 6\%) variations (uncorrelated with those at lower energies) were seen at soft $\gamma$-ray energies of $\sim$100~keV. No significant variability was seen in softer (0.1--1~keV) X-ray bands. In the ultraviolet/optical regime, the NVA decreased from 9\% to 1\% as the wavelength increased from 1275~\AA\ to 6900~\AA. These data do not probe extreme ultraviolet (1200~\AA\ to 0.1~keV) or hard X-ray (2--50~keV) variability. The phase differences between variations in different bands were consistent with zero lag, with upper limits of \ls0.15~day between 1275~\AA\ and the other ultraviolet bands, \ls0.3~day between 1275~\AA\ and 1.5~keV, and \ls1~day between 1275~\AA\ and 5125~\AA. These tight limits represent more than an order of magnitude improvement over those determined in previous multi-waveband AGN monitoring campaigns. The ultraviolet fluctuation power spectra showed no evidence for periodicity, but were instead well-fitted with a very steep, red power-law ($a = -2.5$). If photons emitted at a ``primary" waveband are absorbed by nearby material and ``reprocessed" to produce emission at a secondary waveband, causality arguments require that variations in the secondary band follow those in the primary band. The tight interband correlation and limits on the ultraviolet andComment: 35 pages, LaTeX (including aaspp4), including 7 PostScript figures; To appear in the ApJ (October 20, 1996) Vol. 47

Multiwavelength Observations of Short-Timescale Variability in NGC 4151. I. Ultraviolet Observations

We present the results of an intensive ultraviolet monitoring campaign on the Seyfert I galaxy NGC 4151, as part of an effort to study its short-timescale variability over a broad range in wavelength. The nucleus of NGC 4151 was observed continuously With the International Ultraviolet Explorer for 9.3 days, yielding a pair of LWP and SWP spectra every ~70 minutes, and during 4 hr periods for 4 days Prior to and 5 days after the continuous-monitoring period. The sampling frequency of the observations is an order of magnitude higher than that of any previous UV monitoring campaign on a Seyfert galaxy. The continuum fluxes in bands from 1275 to 2688 A went through four significant and well-defined events of duration 2-3 days during the continuous-monitoring period. We find that the amplitudes of the continuum variations decrease with increasing wavelength, which extends a general trend for this and other Seyfert galaxies to smaller timescales (i.e., a few days). The continuum variations in all the UV bands are simultaneous to within an accuracy of ~0.15 days, providing a strict constraint on continuum models. The emission-line light curves show only one major event during the continuous monitoring (a slow rise followed by a shallow dip) and do not correlate well with continuum light curves over the short duration of the campaign, because the timescale for continuum variations is apparently smaller than the response times of the emission lines.Astronom

Business Simulators in the Educational Process: Comparative Evaluation of the Effectiveness of the Use

There is considerable mobility in the educational services market: stakeholders’ requirements, the forms of organizing the educational process, and the training tools used are changing. Testing of changes requires monitoring and evaluating the effectiveness of improvements and the impact on changes in content parameters, the quality of learning materials and the demand for formed managerial competencies. There is a surge in researchers ‘interest in developing methods for evaluating and justifying the increase in improvements from introducing changes to the educational process. This work reflects the results of an experiment conducted by a research group to expand the tools for teaching students of management training programs. The hypothesis is put about a higher rate of information assimilation and the formation of managerial competencies in groups of students in which classes are organized using business simulators, in contrast to those groups of students who master the course using traditional means - problem solving and case presentation. The authors believe that simulators based on the principles of gamification, to a greater extent satisfy the Generation Z students’ needs for mobility, rapid feedback, change of impressions and locations. The proof of the hypothesis is based on the differentiation of the student group into two subgroups, with a preliminary assessment of students ‘ academic performance in economic and management disciplines and input testing of knowledge in Unit Economics