A Multi-wavelength View of the TeV Blazar Markarian 421: Correlated Variability, Flaring, and Spectral Evolution

We report results from a multi-wavelength monitoring campaign on Mrk 421 over the period of 2003-2004. The source was observed simultaneously at TeV and X-ray energies, with supporting observations frequently carried out at optical and radio wavelengths. The large amount of simultaneous data has allowed us to examine the variability of Mrk 421 in detail. The variabilities are generally correlated between the X-ray and gamma-ray bands, although the correlation appears to be fairly loose. The light curves show the presence of flares with varying amplitudes on a wide range of timescales both at X-ray and TeV energies. Of particular interest is the presence of TeV flares that have no coincident counterparts at longer wavelengths, because the phenomenon seems difficult to understand in the context of the proposed emission models for TeV blazars. We have also found that the TeV flux reached its peak days before the X-ray flux during a giant flare in 2004. Such a difference in the development of the flare presents a further challenge to the emission models. Mrk 421 varied much less at optical and radio wavelengths. Surprisingly, the normalized variability amplitude in optical seems to be comparable to that in radio, perhaps suggesting the presence of different populations of emitting electrons in the jet. The spectral energy distribution (SED) of Mrk 421 is seen to vary with flux, with the two characteristic peaks moving toward higher energies at higher fluxes. We have failed to fit the measured SEDs with a one-zone SSC model; introducing additional zones greatly improves the fits. We have derived constraints on the physical properties of the X-ray/gamma-ray flaring regions from the observed variability (and SED) of the source. The implications of the results are discussed. (Abridged)Comment: 32 pages, 12 figures, to appear in Ap

Business ethics: Are accounting students aware? A Cross-cultural study of four countries

The basic question addressed in this study is whether accounting students, from four countries located in three different continents, are aware of ethical conduct and if there are any differences in awareness among these groups of students. The subjects are from Mississippi State University (United States), the University of the Philippines (Philippines), the University of Indonesia at Jakarta (Indonesia), and University of Tampere (Finland). Specifically, the study examined the studentïs perception of ethical relative to sixteen cases, each of which describes an ethical dilemma. The results showed that, overall, the students from the four universities differ significantly in their perceptions of ethics. The students from the University of the Philippines indicated the highest degree of ethical awareness. The students from Mississippi State University and the University of Tampere showed almost identical scores. In seven of the sixteen cases, all four groups of students clearly showed ethical awareness. All four groups of students were indifferent of situtations that include training sales force on high-pressured selling techniques and hiring employees away from competitors. All four groups of students found nothing wrong with giving awards to customers based on dollar purchases to maintain customers loyalty. All four groups expressed their strongest disapproval of deceitful actions involving unsubstantiated adverstising claim, using high pollutant material to avoid raising price, and selling a banned carcinogen sleepwar in far flung areas with no means of knowing about the danger if the product. The recent emphasis on the inclusion of ethics in business curricula has given rise to the questions of how aware the business student is already of the subject. If the student has already learned of the difference between right and wrong, then the curricula would be different to that which would be required by student who does not know of this difference. The purpose of such a course would be to give the student some understanding of what would be considered ethical conduct before the student moves into the "real" world, whrere each segment of society is trying to define and apply ethical principles as perceived and required within that segment. Thus, in the business segment, a specific set of rules and accetable patterns of behavior have been developed; bankers, lawyers, accountants, doctors and other professionals have specific codes of ethics to which adherence is expected. The purpose of this study is to examine whether accounting students, from four countries located in three continents, viz., Mississippi State University (MSU), University fo the Philippines (UP) in Manila, University of Indonesia (UI) at Jakarta, and University of Tampere (UT) in Finland area aware of ethical conduct and if there are any differences in awareness among these four groups of accounting students

Alternative splicing and genome complexity

Alternative splicing of mRNA allows many gene products with different functions to be produced from a single coding sequence. It has recently been proposed as a mechanism by which higher-order diversity is generated. Here we show, using large-scale expressed sequence tag (EST) analysis, that among seven different eukaryotes the amount of alternative splicing is comparable, with no large differences between humans and other animals

Resonances and Surface Waves in Elastic Wave Scattering from Cavities and Inclusions

Elastic-wave scattering from various types of cavities and inclusions has been studied theoretically with special emphasis on surface wave effects that appear during the scattering process. Resonances in the scattering amplitudes are caused by the phase matching of circumnavigating surface waves, and manifest themselves as poles in the complex frequency plane that correspond to the (complex) eigenfrequencies of the cavity of inclusion. These results are most easily obtained for scatterers of separable geometry, such as spheres, where theoretical amplitudes are well-known. Here, the formalism for a complete treatment of elastic-wave scattering from infinite cylindrical cavities and solid inclusions has been worked out for general oblique incidence. Poles of scattering amplitudes have been found for evacuated and for fluid-filled cylinders, and have been physically interpreted in terms of helical surface waves propagating both interior and exterior to the cylinder. Dispersion, attenuation, and refraction of these surface waves have been obtained. Progressing to more generally-shaped obstacles, we have studied surface waves and complex-frequency poles for finite- length cylindrical cavities with flat ends. In this fashion, the resonance features(particularly the cavity eigenfrequencies) that appear prominently in the scattering amplitude can be understood as to their physical origin and their dependence on the type of cavity, and may be exploited for purposes of classification and identification of flaws by their ultrasonic resonances (ultrasonic “resonance spectroscopy”).</p