137CS gamma-ray detection at Summit, Greenland

Global fall-out from atmospheric testing of thermonuclear weapons produced horizon markers corresponding to the initiation of testing in 1953 and the maximum fall-out in 1963. The radioactive isotope 137Cs associated with these events has a half-life of 30.2 years. Therefore, with the appropriate radiation detectors, this fall-out can be used as a long-term temporal indicator in glaciers and snowpack. A prototype γ-ray detector system was successfully tested and was used to make in-situ measurements of the 137Cs marker in a borehole at Summit, Greenland. The system consisted of a 7.6 cm by 7.6 cm NaI (Tl) scintillation crystal/photomultiplier detector, commercial pre-amplifier, amplifier and power supplies, and a microcomputer-based pulse-height analyzer. The measurements were made in boreholes of 25.4 cm and 12.7 cm diameter to depths of 22 m. Based on the results reported here, the γ-ray detection technique promises to be a powerful way to locate quickly horizon markers in the field. -Author

Study of SMM flares in gamma-rays and neutrons

This report summarizes the results of the research supported by NASA grant NAGW-2755 and lists the papers and publications produced through the grant. The objective of the work was to study solar flares that produced observable signals from high-energy (greater than 10 MeV) gamma-rays and neutrons in the Solar Maximum Mission (SMM) Gamma-Ray Spectrometer (GRS). In 3 of 4 flares that had been studied previously, most of the neutrons and neutral pions appear to have been produced after the 'main' impulsive phase as determined from hard x-rays and gamma-rays. We, therefore, proposed to analyze the timing of the high-energy radiation, and its implications for the acceleration, trapping, and transport of flare particles. It was equally important to characterize the spectral shapes of the interacting energetic electrons and protons - another key factor in constraining possible particle acceleration mechanisms. In section 2.0, we discuss the goals of the research. In section 3.0, we summarize the results of the research. In section 4.0, we list the papers and publications produced under the grant. Preprints or reprints of the publications are attached as appendices

Spectroscopy and Imaging Performance of the Liquid Xenon Gamma-Ray Imaging Telescope (LXeGRIT)

LXeGRIT is a balloon-borne Compton telescope based on a liquid xenon time projection chamber (LXeTPC) for imaging cosmic \g-rays in the energy band of 0.2-20 MeV. The detector, with 400 cm$^2$ area and 7 cm drift gap, is filled with high purity LXe. Both ionization and scintillation light signals are detected to measure the energy deposits and the three spatial coordinates of individual \g -ray interactions within the sensitive volume. The TPC has been characterized with repeated measurements of its spectral and Compton imaging response to \g -rays from radioactive sources such as \na, \cs, \yt and Am-Be. The detector shows a linear response to \g -rays in the energy range 511 keV -4.4 MeV, with an energy resolution (FWHM) of \Delta E/E=8.8% \: \sqrt{1\MeV /E}. Compton imaging of \yt \g -ray events with two detected interactions is consistent with an angular resolution of $\sim$ 3 degrees (RMS) at 1.8 MeV.Comment: To appear in: Hard X-Ray, Gamma-Ray and Neutron Detector Physics XI, 2000; Proc. SPIE, vol. 4140; K.A. Flanagan & O.H. Siegmund, ed

Designing Interactive Secure Systems: CHI 2013 Special Interest Group

Despite a growing interest in the design and engineering of interactive secure systems, there is also a noticeable amount of fragmentation. This has led to a lack of awareness about what research is currently being carried out, and misunderstandings about how different fields can contribute to the design of usable and secure systems. By drawing interested members of the CHI community from design, user experience, engineering, and HCI Security, this SIG will take the first steps towards creating a research agenda for interactive secure system design. In the SIG, we will summarise recent initiatives to develop a research programme in interactive secure system design, network members of the CHI community with an interest in this research area, and initiate a roadmap towards addressing identified research challenges and building an interactive secure system design community

Electronic Footprints in the Sand: Technologies for Assisting Domestic Violence Survivors

With the rapid growth and spread of Internet-based social support systems, the impact that these systems can make to society – be it good or bad – has become more significant and can make a real difference to people’s lives. As such, various aspects of these systems need to be carefully investigated and analysed, including their security/privacy issues. In this paper, we present our work in designing and implementing various technological features that can be used to assist domestic violence survivors in obtaining help without leaving traces which might lead to further violence from their abuser. This case study serves as the core of our paper, in which we outline our approach, various de- sign considerations – including difficulties in keeping browsing history private, our currently implemented solutions (single use URL, targeted history sanitita- tion agent, and secret graphical gateway), as well as novel ideas for future work (including location-based service advertising and deployment in the wild)

Analysis of the 0.511 MeV radiation at the OSO-7 satellite

Observations of the 0.511 MeV positron annihilation, gamma ray on the OSO-7 satellite are presented. Variables which affect the counting rate are discussed. An upper limit flux of .0076 photons/sq cm/sec is obtained for the quiet sun and a positive solar flux of .063(+ or - .0002) photons/sq cm/sec is obtained for the 3B flare of 4 August 1972. The width of this annihilation line gives an upper limit temperature for the annihilation region of approximately 6 million K. An analysis of the line width and position also shows that the contribution to the line from positronium annihilation is less than 100% at the 99% confidence level. An upper limit is also found for an isotropic cosmic flux

The effect of explicitly differentiated reading instruction groups on eighth-grade students\u27 achievement, behavior, and engagement in a school seeking to reestablish adequate yearly progress benchmarks

The purpose of this study was to determine the effect of explicitly differentiated reading instruction groups on eighth-grade students’ achievement, behavior, and engagement in a school seeking to reestablish adequate yearly progress benchmarks. The results of this study supported student participation in explicitly differentiated reading instruction groups. Because students in High Reading Ability (n = 25), Middle Reading Ability (n = 25), and Low Reading Ability (n = 25) groups maintained average to above average achievement test scores on several measures with commensurate classroom grade performance, and appropriate behavior and engagement to support school success during eighth grade, the results suggest continued implementation of explicitly differentiated reading instruction classrooms. Faced with the imperative to acquire literacy skills adequate to meet the academic demands of the high school educational process and post-secondary life as either college student or working adult, learning must be accelerated for all segments of the student population. Additionally, this acceleration is fundamental to the school’s ability to meet No Child Left Behind requirements and attain levels of student achievement commensurate with legislative expectations. Researchers have clearly developed answers for pedagogical questions surrounding which instructional components enable and accelerate the development of critical reading skills that include differentiated instruction that is intensive and frequent. Moreover, practitioners are cautioned that traditional classroom instruction may not provide enough of these components to accelerate learning and skills acquisition. The results of this study suggest that when these critical components are present in the daily educational routine, supported by the student schedule and teacher roster assignment, achievement can be significantly positively influenced

Was Sinn Féin dying? A quantitative post-mortem of the party's decline and the emergence of Fianna Fáil

This article calls for a reappraisal of the consensus surrounding the split within Sinn Féin in 1926 that led to the foundation of Fianna Fáil. It demonstrates that quantitative factors cited to demonstrate Sinn Féin’s “terminal” decline – finances, cumann numbers, and election results – and to explain de Valera’s decision to leave Sinn Féin and establish a rival republican organisation, Fianna Fáil, do not provide sufficient objective grounds to explain the republican leader’s actions. This article demonstrates that Sinn Féin’s election results during the period in question (1923-1926) were encouraging and the decline in finances and cumann numbers can be explained by the fact that the base year used to compare progress was 1923, an election year. Moreover, this article compares the performance of Sinn Féin to the first five years of Fianna Fáil (1926-1931) to show that what has been interpreted as terminal decline can also be attributed to normal inter-election lulls in party activity. Correspondingly, subjective factors – e.g. personal rivalries, differences in ideology, organisational style and levels of patience in terms of achieving political power – were most likely the determining factors rather than organisational decline