Studies of neutron and proton nuclear activation in low-Earth orbit

The expected induced radioactivity of experimental material in low Earth orbit was studied for characteristics of activating particles such as cosmic rays, high energy Earth albedo neutrons, trapped protons, and secondary protons and neutrons. The activation cross sections for the production of long lived radioisotopes and other existing nuclear data appropriate to the study of these reactions were compiled. Computer codes which are required to calculate the expected activation of orbited materials were developed. The decreased computer code used to predict the activation of trapped protons of materials placed in the expected orbits of LDEF and Spacelab II. Techniques for unfolding the fluxes of activating particles from the measured activation of orbited materials are examined

An Architectural Approach to Ensuring Consistency in Hierarchical Execution

Hierarchical task decomposition is a method used in many agent systems to organize agent knowledge. This work shows how the combination of a hierarchy and persistent assertions of knowledge can lead to difficulty in maintaining logical consistency in asserted knowledge. We explore the problematic consequences of persistent assumptions in the reasoning process and introduce novel potential solutions. Having implemented one of the possible solutions, Dynamic Hierarchical Justification, its effectiveness is demonstrated with an empirical analysis

Study of proton and neutron activation of metal samples in low Earth orbit

Progress in the following activities has been made: the analysis of the gamma ray spectra taken from samples flown in Spacelab 2; the search for and review of neutron and proton activation cross sections needed to analyze the results of the Long Duration Exposure Facility (LDEF) activation measurements; the consideration given to data analysis of the LDEF and Spacelab 2 samples; the plan to measure relevant cross sections with nuclear accelerator measurements; and the preparation of an extended gamma ray calibration sources continues through planning and direct measurement of gamma ray efficiency for a Ge(Li) as a function of position along the surface of the detector housing

Flexibly Instructable Agents

This paper presents an approach to learning from situated, interactive tutorial instruction within an ongoing agent. Tutorial instruction is a flexible (and thus powerful) paradigm for teaching tasks because it allows an instructor to communicate whatever types of knowledge an agent might need in whatever situations might arise. To support this flexibility, however, the agent must be able to learn multiple kinds of knowledge from a broad range of instructional interactions. Our approach, called situated explanation, achieves such learning through a combination of analytic and inductive techniques. It combines a form of explanation-based learning that is situated for each instruction with a full suite of contextually guided responses to incomplete explanations. The approach is implemented in an agent called Instructo-Soar that learns hierarchies of new tasks and other domain knowledge from interactive natural language instructions. Instructo-Soar meets three key requirements of flexible instructability that distinguish it from previous systems: (1) it can take known or unknown commands at any instruction point; (2) it can handle instructions that apply to either its current situation or to a hypothetical situation specified in language (as in, for instance, conditional instructions); and (3) it can learn, from instructions, each class of knowledge it uses to perform tasks.Comment: See http://www.jair.org/ for any accompanying file

SU(N) Fermions in a One-Dimensional Harmonic Trap

We conduct a theoretical study of SU(N) fermions confined by a one-dimensional harmonic potential. Firstly, we introduce a new numerical approach for solving the trapped interacting few-body problem, by which one may obtain accurate energy spectra across the full range of interaction strengths. In the strong-coupling limit, we map the SU(N) Hamiltonian to a spin-chain model. We then show that an existing, extremely accurate ansatz - derived for a Heisenberg SU(2) spin chain - is extendable to these N-component systems. Lastly, we consider balanced SU(N) Fermi gases that have an equal number of particles in each spin state for N=2, 3, 4. In the weak- and strong-coupling regimes, we find that the ground-state energies rapidly converge to their expected values in the thermodynamic limit with increasing atom number. This suggests that the many-body energetics of N-component fermions may be accurately inferred from the corresponding few-body systems of N distinguishable particles.Comment: 15 pages, 6 figure

Protecting children from nutritional and medical neglect in sub-Saharan Africa: a five-country study

This study focuses on the dominant definitions of nutritional and medical neglect used to identify child maltreatment. These originate from the United Kingdom and the United States, but are also utilised in the developing countries of the sub-Saharan region. Evidence adduced from secondary data gathered in five representative African countries seeks to demonstrate that the application of these dominant definitions of neglect is misleading in the socio-economic context which pertains in most of the sub-Saharan region. The statutes which domesticate the Convention on the Rights of the Child (CRC) in these African countries are examined to reveal some distinctive national variations in their child protection provisions. While predominantly reflecting Western definitions of neglect, some of the legal provisions embedded in African domestic laws offer insights into more functional concepts of child neglect. Notably some recognise a tension between deprivation which denies parents the resources to satisfactorily care for their child, and neglect whereby adequately resourced parents deny their child nourishment and medical assistance

The representation of the family’s voice in serious case review reports of child maltreatment

Australia and the United Kingdom have a mandatory system of case reviews, which are conducted whenever a child known to welfare or health services has died or been seriously harmed due to maltreatment. In the United Kingdom those conducting case reviews are required to involve family members in their deliberations. This study employed discourse analysis to examine the representation of family voices in 41 Overview Reports of Serious Case Reviews undertaken in England and published during 2014. The findings revealed that the contributions of family members were generally relegated or their legitimacy undercut by the positivist framing of most Overview Reports. However, the research also identified how the framing of family contributions within an interpretivist paradigm could engender highly complex understanding of deficiencies in child protection systems and lead to crucial new learning for professionals

Developing Student Agency in the Choral Classroom: A Case Study

This multiple-case study sought to describe how student agency is cultivated within two high school choir programs. Research questions were: (a) In what ways did participating teachers incorporate student agency? (b) How did their students describe their experience? (c) What opportunities/difficulties emerged when students assumed leadership and decision-making roles? (d) Why do participating teachers offer these to students? (e) How do opportunities for student agency serve student learning and program goals? Data collection included semi-structured teacher interviews in two stages, as well as a student questionnaire. Other data included choir handbooks, student leadership information, social media presence, and classroom signs. Emergent themes were examined through Emirbayer and Mische’s (1998) temporal-relational view of agency, in which actors make choices within a “temporally embedded process of social engagement, informed by the past, but oriented towards the future and… present”(p. 963) . Iterative agency was exercised as students took actions based on their previous choir and leadership experiences. Opportunities for practical-evaluative agency included student-led sectionals, planning and executing choir events, and making interpretive musical decisions. Teachers considered students’ projective agency through intentional music literacy instruction (“literate, thinking musicians”) and promoting virtues (“better people”). A culture of strong relationships and a safe environment promoted agency. Implications for teaching practice include incorporating student-centered instructional activities into rehearsal: student-led sectionals, discussions about musical interpretation, and questioning techniques. Teachers could choose student conductors or allowing students to rehearse the entire ensemble when directors are absent. Student leadership structures that allow students to participate throughout high school were beneficial, including regular opportunities for director guidance and communication. While directors still retain primary authority, students can be given more agency and autonomy in certain areas, such as culturally relevant performances and social aspects of choir life. All data was collected during the COVID-19 pandemic; therefore, observations were not possible. Gatekeepers in one district did not allow student interviews. As a result, implications for future research include multiple periodic observations over the course of a school year, and incorporation of student interviews. Future studies could investigate the presence of student agency in urban schools, and those lacking strong feeder programs