Measurement of dimensional stability

A technique was developed for measuring, with a precision of one part 10 to the 9th power, changes in physical dimensions delta L/L. Measurements have commenced on five materials: Heraeus-Schott Homosil (vitreous silica), Corning 7940 (vitreous silica), Corning ULE 7971 (titanium silicate), Schott Zero-Dur, and Owens-Illinois Cer-Vit C-101. The study was extended to include Universal Cyclops Invar LR-35 and Simonds-Saw Superinvar

Theme Schools: From Manifesto to Paradigm for Undergraduate Students

In sciences, when anomalies or discrepant observations generate a crisis, so that the old way of looking at things no longer suffices to explain or predict observable events, scientists construct a new paradigm (Kuhn, 1996). Despite vast differences in our backgrounds and in the attributes of our widely separated home institutions, we have arrived at strikingly similar perceptions of the need to fashion a new paradigm within undergraduate education. By aligning the anomalies and assembling experiences from several correlative efforts within the old paradigm, we have begun to distill some tenets of a coherent rationale for student-centred learning, built around the concepts inherent in a "theme school." These tenets are especially relevant to small, widely dispersed northern communities. Much of the following discussion originates in our shared disappointments with the effectiveness of education by the traditional Euro-American undergraduate paradigm when applied to northern environments and rural communities. Nevertheless, we are not institution-bashing: we owe much, after all, to the institutions that provided us with a point of departure for exploring alternatives and supplements

Fly-by-light flight control system technology development plan

The results of a four-month, phased effort to develop a Fly-by-Light Technology Development Plan are documented. The technical shortfalls for each phase were identified and a development plan to bridge the technical gap was developed. The production configuration was defined for a 757-type airplane, but it is suggested that the demonstration flight be conducted on the NASA Transport Systems Research Vehicle. The modifications required and verification and validation issues are delineated in this report. A detailed schedule for the phased introduction of fly-by-light system components has been generated. It is concluded that a fiber-optics program would contribute significantly toward developing the required state of readiness that will make a fly-by-light control system not only cost effective but reliable without mitigating the weight and high-energy radio frequency related benefits

Contributions to the Science of Environmental Impact Assessment: Three Papers on the Arctic Cisco (Coregonus autumnalis) of Northern Alaska

Editor's Introduction -- D. W. Norton; An Assessment of the Colville River Delta Stock of Arctic Cisco--Migrants from Canada? -- B. J. Gallaway, W. B. Griffiths, P. C. Craig, W. J. Gazey, and J. W. Helmericks; Temperature Preference of Juvenile Arctic Cisco (Coregonus autumnalis) From the Alaskan Beaufort Sea -- R. G. Fechhelm, W. H. Neill, and B. J. Gallaway; Modeling Movements and Distribution of Arctic Cisco (Coregonus autumnalis) Relative to Temperature-Salinity Regimes of the Beaufort Sea Near the Waterflood Causeway, Prudhoe Bay, Alaska. -- W. H. Neill, R. G. Fechhelm, B. J. Gallaway, J. D. Bryan, and S. W. Anderson; Notice to Author

'These Discussions Aren't Happening': Experiences of People Living with Inflammatory Bowel Disease and Talking About Sexual Well-being with Health Care Professionals.

Background Inflammatory bowel disease [IBD] affects all aspects of life, yet little is known about the impact of the condition on intimacy and sexuality and if such concerns should be discussed with health care professionals. This hermeneutical phenomenological study aimed to explore the experiences of people living with inflammatory bowel disease and discussing their sexuality concerns with health care professionals. Methods Participants [n = 43] aged 17–64 years were recruited. Data were collected via in depth interviews and anonymous narrative accounts [Google Forms]. Thematic analysis was used to analyse the data. Results An overarching theme ‘These discussions aren’t happening’ with four main themes were generated. The main themes were: ‘I can’t image talking about sex’; ‘I am a person, not my IBD’; ‘We need to talk about sex’; and ‘Those who talked about sex, talked badly’. Participants described the lack of conversations with their health care professionals on sexual well-being issues, in spite of the importance they gave to the topic, and identified barriers to having such conversations. They made suggestions for future clinical practice that would better meet their needs. The few who had discussed sexual well-being issues with health care professionals reported negative experiences. Conclusions Patients’ needs and preferences, about addressing during clinical appointments concerns related to their sexual well-being, should be addressed routinely and competently by health care professionals. Understanding the implications of inflammatory bowel disease for intimate aspects of the lives of those living with the condition could improve the quality of the care provided

Short-Distance Structure of Nuclei

One of Jefferson Lab's original missions was to further our understanding of the short-distance structure of nuclei. In particular, to understand what happens when two or more nucleons within a nucleus have strongly overlapping wave-functions; a phenomena commonly referred to as short-range correlations. Herein, we review the results of the (e,e'), (e,e'p) and (e,e'pN) reactions that have been used at Jefferson Lab to probe this short-distance structure as well as provide an outlook for future experiments.Comment: 16 pages, 8 figures, for publication in Journal of Physics

Magnetic interactions in transition metal doped ZnO : An abinitio study

We calculate the nature of magnetic interactions in transition-metal doped ZnO using the local spin density approximation and LSDA+\textit{U} method of density functional theory. We investigate the following four cases: (i) single transition metal ion types (Cr, Mn, Fe, Co, Ni and Cu) substituted at Zn sites, (ii) substitutional magnetic transition metal ions combined with additional Cu and Li dopants, (iii) substitutional magnetic transition metal ions combined with oxygen vacancies and (iv) pairs of magnetic ion types (Co and Fe, Co and Mn, etc.). Extensive convergence tests indicate that the calculated magnetic ground state is unusually sensitive to the k-point mesh and energy cut-off, the details of the geometry optimizations and the choice of the exchange-correlation functional. We find that ferromagnetic coupling is sometimes favorable for single type substitutional transition metal ions within the local spin density approximation. However, the nature of magnetic interactions changes when correlations on the transition-metal ion are treated within the more realistic LSDA + \textit{U} method, often disfavoring the ferromagnetic state. The magnetic configuration is sensitive to the detailed arrangement of the ions and the amount of lattice relaxation, except in the case of oxygen vacancies when an antiferromagnetic state is always favored.Comment: 11 pages, 17 figure

Heat Transfer Operators Associated with Quantum Operations

Any quantum operation applied on a physical system is performed as a unitary transformation on a larger extended system. If the extension used is a heat bath in thermal equilibrium, the concomitant change in the state of the bath necessarily implies a heat exchange with it. The dependence of the average heat transferred to the bath on the initial state of the system can then be found from the expectation value of a hermitian operator, which is named as the heat transfer operator (HTO). The purpose of this article is the investigation of the relation between the HTOs and the associated quantum operations. Since, any given quantum operation on a system can be realized by different baths and unitaries, many different HTOs are possible for each quantum operation. On the other hand, there are also strong restrictions on the HTOs which arise from the unitarity of the transformations. The most important of these is the Landauer erasure principle. This article is concerned with the question of finding a complete set of restrictions on the HTOs that are associated with a given quantum operation. An answer to this question has been found only for a subset of quantum operations. For erasure operations, these characterizations are equivalent to the generalized Landauer erasure principle. For the case of generic quantum operations however, it appears that the HTOs obey further restrictions which cannot be obtained from the entropic restrictions of the generalized Landauer erasure principle.Comment: A significant revision is made; 33 pages with 2 figure