Effects of liquid and vapor cesium on structural materials

Literature survey on corrosive effects of liquid and vapor cesium on structural materials, and compatibility of cesium as working fluid for Rankine cycle space power plan

Exciton-Exciton Annihilation Is Coherently Suppressed in H-Aggregates, but Not in J-Aggregates

We theoretically demonstrate a strong dependence of the annihilation rate between (singlet) excitons on the sign of dipole-dipole couplings between molecules. For molecular H-aggregates, where this sign is positive, the phase relation of the delocalized two-exciton wavefunctions causes a destructive interference in the annihilation probability. For J-aggregates, where this sign is negative, the interference is constructive instead, as a result of which no such coherent suppression of the annihilation rate occurs. As a consequence, room temperature annihilation rates of typical H- and J-aggregates differ by a factor of ~3, while an order of magnitude difference is found for low-temperature aggregates with a low degree of disorder. These findings, which explain experimental observations, reveal a fundamental principle underlying exciton-exciton annihilation, with major implications for technological devices and experimental studies involving high excitation densities

Island formation without attractive interactions

We show that adsorbates on surfaces can form islands even if there are no attractive interactions. Instead strong repulsion between adsorbates at short distances can lead to islands, because such islands increase the entropy of the adsorbates that are not part of the islands. We suggest that this mechanism cause the observed island formation in O/Pt(111), but it may be important for many other systems as well.Comment: 11 pages, 4 figure

An Exploration of Knowledge Translation Amongst Homecare Providers, Family Caregivers, and Clients

The aim of this two-phased investigation was to enhance understanding of urinary incontinence (UI) knowledge translation (KT) to inform how UI management knowledge might be translated within in-home nursing practice and family caregiving. Although UI can be managed conservatively, it is a principal reason for the breakdown of family-care and care recipient admission to long-term care. Research has afforded little insight into family caregivers’ experience of KT and the process of in-home KT for UI management. The first study used a hermeneutic phenomenological approach to explore family caregivers’ experience of UI KT. Data were collected from in-depth interviews with a purposive sample of caregivers (n=4) and analyzed with immersion and crystallization interpretive methods. KT was experienced through the social interaction of working together/not working together that was contextualized by homecare and personal attributes. The phase two grounded theory study explored the enactment of in-home KT. In-depth interview data were collected from a theoretical sample of 23 family caregivers, homecare recipients, and homecare providers. Constant comparison and Glaser’s analysis criteria were used to create the substantive theory of Translating Knowledge Through Relating. Findings illuminated how intersubjectivity and bi-directional relational interactions are interlinked in and essential to translating in-home care knowledge which is largely tacit and experiential in nature. Insights afforded understandings about how relational practice is necessary to foster mutual and equitable social construction of KT. The practical application of ‘Translating Knowledge Through Relating’ may constitute an important component of promoting health as a resource for everyday living with UI

Fluid thrust control system

A pure fluid thrust control system is described for a pump-fed, regeneratively cooled liquid propellant rocket engine. A proportional fluid amplifier and a bistable fluid amplifier control overshoot in the starting of the engine and take it to a predetermined thrust. An ejector type pump is provided in the line between the liquid hydrogen rocket nozzle heat exchanger and the turbine driving the fuel pump to aid in bringing the fluid at this point back into the regular system when it is not bypassed. The thrust control system is intended to function in environments too severe for mechanical controls

Fast and Simple Relational Processing of Uncertain Data

This paper introduces U-relations, a succinct and purely relational representation system for uncertain databases. U-relations support attribute-level uncertainty using vertical partitioning. If we consider positive relational algebra extended by an operation for computing possible answers, a query on the logical level can be translated into, and evaluated as, a single relational algebra query on the U-relation representation. The translation scheme essentially preserves the size of the query in terms of number of operations and, in particular, number of joins. Standard techniques employed in off-the-shelf relational database management systems are effective for optimizing and processing queries on U-relations. In our experiments we show that query evaluation on U-relations scales to large amounts of data with high degrees of uncertainty.Comment: 12 pages, 14 figure