Regional Evolutions

macroeconomics, regional evolutions

Time Domain Studies of X-ray Shot Noise in Cygnus X-1

We investigate the variability of Cygnus X-1 in the context of shot moise models, and employ a peak detection algorithm to select individual shots. For a long observation of the low, hard state, the distribution of time intervals between shots is found to be consistent with a purely random process, contrary to previous claims in the literature. The detected shots are fit to several model templates and found to have a broad range of shapes. The fitted shots have a distribution of timescales from below 10 milliseconds to above 1 second. The coherence of the cross spectrum of light curves of these data in different energy bands is also studied. The observed high coherence implies that the transfer function between low and high energy variability is uniform. The uniformity of the tranfer function implies that the observed distribution of shot widths cannot have been acquired through Compton scattering. Our results in combination with other results in the literature suggest that shot luminosities are correlated with one another. We discuss how our experimental methodology relates to non-linear models of variability.Comment: Accepted for publication in Astrophysical Journal on July 16, 200

Assessing high school students\u27 conceptions of the size, age, and distance of astronomical objects

The purpose of this research study is to identify student conceptions about the size, distance, and age of various objects associated with space science. After reviewing the literature related to this study, there seems to be a need for continued research at the high school level in the field of astronomy conceptualization

Some investigations concerning the glands associated with the skin of the mollusc Arion hortensis (fer)

The structure and histochemistry of the gland cells of the dorsal and ventral surfaces of Arion hortensis were described, together with that of the pedal and caudal glands. This investigation was conducted using a light microscope and standard staining techniques. The ultrastructure of the pedal gland was investigated and the nature of an unusual tubule - filled endoplasmic reticulum considered and describedo The effect of the enzyme pepsin, and of deamination on the ultrastructure of the tubules, was examined. Lastly, a brief regeneration experiment was conducted, using mantle tissue, to study the origin of the gland cells. The process was first investigated using a light microscope, and then tissue from a limited time sequence was studied using the electron microscope. These last results were compared with the ultrastructure of the normal mantle