Editor\u27s Concluding Comments

Editor’s Concluding Remark

Appalachian and Rural Student Performance Differences on Kentucky\u27s Educational Assessment: Eighth Grade Results

For assessment and accountability, the Kentucky Department of Education (KDE) developed the Kentucky Instructional Results Information System (KIRIS). Because the KIRIS assessment relied on student performance and was “high stakes” for schools, the fairness of the assessment was important. This paper examined whether 8th grade students living in Appalachia and/or in primarily rural school districts perform differently on the assessment than their peers. The four years of data (1993-1996) for this study came from KIRIS Cycle 2 data. The dependent variable was a composite score of student performance on constructed-response reading, mathematics, science, and social studies tests. The study found very small but significant performance differences existed based on Appalachian residence and rural-urban mix of school district over this KIRIS Accountability Cycle. Several suggestions for further decomposing the patterns of difference found in this study are made

Editor\u27s Preface

introduction of Doug Smith as new editor of SR

The experiences of first time fathers in Western Australia: A qualitative analysis into the transition to fatherhood

According to critical life events framework, the transition to parenthood can be filled with anticipation and excitement, yet it can be extremely difficult for some. The transition to parenthood begins during pregnancy when the parents begin to form emotional bonds with the unborn child, and continues for some time after the birth of the baby, ending when the infant reaches two years of age. There exists a vast amount of research on the experiences of the female transition, but there is little in comparison about the experiences of the male transition to becoming a father for the first time. The aim of this research was to investigate the experiences of first time fathers in Perth, Western Australia, in the 21st century. Using thematic content analysis, interviews with five first time fathers aged between 25 and 38 (M = 31, SD = 6.12), with infants aged between 2 and 20 months (M = 8.8, SD = 8.23) were conducted. Whilst there is a deficiency in current empirical evidence on the transitional experience of first time fathers in Western Australia, the data revealed aspects of fatherhood that are traditionally ignored. This revelation is two-fold in benefit, in that it acknowledges and adds meaning to the male perspective in child rearing, and adds to the body of literature outside other countries such as the United States of America. This research may aid health care professionals gain a better understanding of the issues faced by first time fathers, and identifies the need for improvement in current education and information packages assisting first time fathers with their transition to fatherhood

Digital Signcryption

Signcryption is a new cryptographic primitive which simultaneously provides both confidentiality and authenticity. Previously, these two goals had been considered separately, with encryption schemes providing confidentiality and signature schemes providing authenticity. In cases where both were required, the encryption and signature operations were simply sequentially composed. In 1997, Zheng demonstrated that by combining both goals into a single primitive, it is possible to achieve significant savings both in computational and communication overhead. Since then, a wide variety of signcryption schemes have been proposed. In this thesis, we present a number of the proposed signcryption schemes in terms of a common framework. For the most part, the material has been previously presented in various research papers, but some previously omitted proofs have been filled in here. We begin by giving a formal definition of the signcryption primitive, complete with a security model. Then we look at some of the various proposed signcryption schemes, and consider their relative advantages and disadvantages. Finally, we look ahead at what future progress might be made in the field

The Effects of Race, Place, Class, and Gender on Instructional Strategies in Kentucky\u27s Seventh Grade Science Classes: Individual and School Level Analyses

This study explored the relationship of student demographics to teaching method in Kentucky’s seventh grade science classrooms for 1997-98, based on performance assessment data (student level N = 21,499; school level N = 264). Students’ perceptions of seven instructional strategies from the KIRIS student questionnaires were placed into three groups: traditional, inquiry-based, and computer. At the student level, these strategies were regressed on race, gender, free/reduced lunch, urbanity of the district, Appalachian status, and Educational Service Region. At the school level, the three approaches were regressed on aggregate school data for these same variables. Findings indicated that demographic factors do affect teachers’ instructional strategies. Student-level results demonstrated numerous small but statistically significant influences on all three instructional approaches. Nearly all demographic effects disappeared when examined at the school level. The strongest finding was that schools with higher percentages of free/reduced lunch students reported more computer usage. Less computer use was reported for schools with more female students. Findings are discussed in light of science instruction, computers, and technological development for the rural south

Criticality experiments with planar arrays of three-liter bottles containing plutonium nitrate solution

The objective of these experiments was to provide benchmark data to validate calculational codes used in critically safety assessments of plant configurations. Arrays containing up to as many as sixteen three-liter bottles filled with plutonium nitrate were used in the experiments. A split-table device was used in the final assembly of the arrays. Ths planar arrays were reflected with close fitting plexiglas on each side and on the bottom but not the top surface. The experiments addressed a number of factors effecting criticality: the critical air gap between bottles in an array of fixed number of bottles, the number of bottles required for criticality if the bottles were touching, and the effect on critical array spacing and critical bottle number due to the insertion of an hydrogeneous substance into the air gap between bottles. Each bottle contained about 2.4l of Pu(NO{sub 3}){sub 4} solution at a Pu concentration of 105g Pu/l, with the {sup 240}Pu content being 2.9 wt% at a free acid molarity H{sup +} of 5.1. After the initial series of experiments were performed with bottles separated by air gaps, plexiglas shells of varying thicknesses were placed around each bottle to investigate how moderation between bottles affects both the number of bottles required for criticality and the critical spacing between each bottle. The minimum of bottles required for criticality was found to be 10.9 bottles, occurring for a square array with bottles in contact. As the bottles were spaced apart, the critical number increased. For sixteen bottles in a square array, the critical separation between surfaces in both x and y direction was 0.96 cm. The addition of plexiglas around each bottle decreased the critical bottle number, compared to those separated in air, but the critical bottle number, even with interstitial plastic in place was always greater than 10.9 bottles. The most reactive configuration was a tightly packed array of bottles with no intervening material

Small magellanic cloud-type interstellar dust in the milky way

It is well known that the sight line toward HD 204827 in the cluster Trumpler 37 shows a UV extinction curve that does not follow the average Galactic extinction relation. However, when a dust component, fore-ground to the cluster, is removed, the residual extinction curve is identical to that found in the SMC within the uncertainties. The curve is very steep and has little or no 2175 A bump. The position of HD 204827 in the sky is projected onto the edge of the Cepheus IRAS bubble. In addition, HD 204827 has an IRAS bow shock, indicating that it may be embedded in dust swept up by the supernova that created the IRAS bubble. Shocks due to the supernova may have led to substantial processing of this dust. The HD 204827 cloud is dense and rich in carbon molecules. The 3.4 μm feature indicating a C-H grain mantle is present in the dust toward HD 204827. The environment of the HD 204827 cloud dust may be similar to the dust associated with HD 62542, which lies on the edge of a stellar wind bubble and is also dense and rich in molecules. This sight line may be a Rosetta Stone if its environment can be related to those in the SMC having similar dust

Evidence for Pre-Existing Dust in the Bright Type IIn SN 2010jl

SN 2010jl was an extremely bright, Type IIn SNe which showed a significant IR excess no later than 90 days after explosion. We have obtained Spitzer 3.6 and 4.5 \mum and JHK observations of SN 2010jl \sim90 days post explosion. Little to no reddening in the host galaxy indicated that the circumstellar material lost from the progenitor must lie in a torus inclined out of the plane of the sky. The likely cause of the high mid-IR flux is the reprocessing of the initial flash of the SN by pre-existing circumstellar dust. Using a 3D Monte Carlo Radiative Transfer code, we have estimated that between 0.03-0.35 Msun of dust exists in a circumstellar torus around the SN located 6 \times 10 ^17 cm away from the SN and inclined between 60-80\cdot to the plane of the sky. On day 90, we are only seeing the illumination of approximately 5% of this torus, and expect to see an elevated IR flux from this material up until day \sim 450. It is likely this dust was created in an LBV-like mass loss event of more than 3 Msun, which is large but consistent with other LBV progenitors such as {\eta} Carinae.Comment: Accepted in A

Are Ti44-Producing Supernovae Exceptional?

According to standard models supernovae produce radioactive $^{44}$Ti, which should be visible in gamma-rays following decay to $^{44}$Ca for a few centuries. $^{44}Ti production is believed to be the source of cosmic$^{44}$Ca, whose abundance is well established. Yet, gamma-ray telescopes have not seen the expected young remnants of core collapse events. The$^{44}$Ti mean life of$\tau \simeq$89 y and the Galactic supernova rate of$\simeq$3/100 y imply$\simeq$several detectable$^{44}Ti gamma-ray sources, but only one is clearly seen, the 340-year-old Cas A SNR. Furthermore, supernovae which produce much $^{44}Ti are expected to occur primarily in the inner part of the Galaxy, where young massive stars are most abundant. Because the Galaxy is transparent to gamma-rays, this should be the dominant location of expected gamma-ray sources. Yet the Cas A SNR as the only one source is located far from the inner Galaxy (at longitude 112 degree). We evaluate the surprising absence of detectable supernovae from the past three centuries. We discuss whether our understanding of SN explosions, their$^{44}Ti yields, their spatial distributions, and statistical arguments can be stretched so that this apparent disagreement may be accommodated within reasonable expectations, or if we have to revise some or all of the above aspects to bring expectations in agreement with the observations. We conclude that either core collapse supernovae have been improbably rare in the Galaxy during the past few centuries, or $^{44}Ti-producing supernovae are atypical supernovae. We also present a new argument based on$^{44}$Ca/$^{40}$Ca ratios in mainstream SiC stardust grains that may cast doubt on massive-He-cap Type I supernovae as the source of most galactic$^{44}$Ca.Comment: 23 pages, 14 figures, accepted for publication in Astronomy and Astrophysics 2006. Correcting the SN type of Tycho in Table B.1. and add its associated reference