8,984 research outputs found
Ion chambers simplify absolute intensity measurements in the vacuum ultraviolet
Single or double ion chamber technique measures absolute radiation intensities in the extreme vacuum ultraviolet region of the spectrum. The ion chambers use rare gases as the ion carrier. Photon absorbed by the gas creates one ion pair so a measure of these is a measure of the number of incident photons
Application of airborne infrared technology to monitor building heat loss
The application of airborne infrared technology to the requirements for energy conservation in buildings was studied. Quantitative airborne data of the City of Ypsilanti, Michigan, were collected and processed to identify roof temperatures. A thermal scanner was flown at an altitude of 1,200 feet with two thermal bands 8.2-9.3 micrometers and 10.4-12.5 micrometers recorded by an analog system. Calibration was achieved by standard hot and cold plates. Using a thermal model to interpret ceiling insulation status, environmental factors were found to influence the relation between roof temperature and insulation. These include interior and sky temperatures, roofing materials, and the pitch and orientation of the roof. A follow-up mail survey established the ability to identify insulated and uninsulated houses from the airborne infrared data
The ROTSE-III Robotic Telescope System
The observation of a prompt optical flash from GRB990123 convincingly
demonstrated the value of autonomous robotic telescope systems. Pursuing a
program of rapid follow-up observations of gamma-ray bursts, the Robotic
Optical Transient Search Experiment (ROTSE) has developed a next-generation
instrument, ROTSE-III, that will continue the search for fast optical
transients. The entire system was designed as an economical robotic facility to
be installed at remote sites throughout the world. There are seven major system
components: optics, optical tube assembly, CCD camera, telescope mount,
enclosure, environmental sensing & protection and data acquisition. Each is
described in turn in the hope that the techniques developed here will be useful
in similar contexts elsewhere.Comment: 19 pages, including 4 figures. To be published in PASP in January,
2003. PASP Number IP02-11
The GREAT triggerless total data readout method
Recoil decay tagging (RDT) is a very powerful method for the spectroscopy of exotic nuclei. RDT is a delayed coincidence technique between detectors usually at the target position and at the focal plane of a spectrometer. Such measurements are often limited by dead time. This paper describes a novel triggerless data acquisition method, which is being developed for the Gamma Recoil Electron Alpha Tagging (GREAT) spectrometer, that overcomes this limitation by virtually eliminating dead time. Our solution is a total data readout (TDR) method where all channels run independently and are associated in software to reconstruct events. The TDR method allows all the data from both target position and focal plane to be collected with practically no dead-time losses. Each data word is associated with a timestamp generated from a global 100-MHz clock. Events are then reconstructed in real time in the event builder using temporal and spatial associations defined by the physics of the experimen
de Sitter geodesics: reappraising the notion of motion
The de Sitter spacetime is transitive under a combination of translations and
proper conformal transformations. Its usual family of geodesics, however, does
not take into account this property. As a consequence, there are points in de
Sitter spacetime which cannot be joined to each other by any one of these
geodesics. By taking into account the appropriate transitivity properties in
the variational principle, a new family of maximizing trajectories is obtained,
whose members are able to connect any two points of the de Sitter spacetime.
These geodesics introduce a new notion of motion, given by a combination of
translations and proper conformal transformations, which may possibly become
important at very-high energies, where conformal symmetry plays a significant
role.Comment: 9 pages. V2: Presentation changes aiming at clarifying the text;
version accepted for publication in Gen. Rel. Gra
Naming Game on Adaptive Weighted Networks
We examine a naming game on an adaptive weighted network. A weight of
connection for a given pair of agents depends on their communication success
rate and determines the probability with which the agents communicate. In some
cases, depending on the parameters of the model, the preference toward
successfully communicating agents is basically negligible and the model behaves
similarly to the naming game on a complete graph. In particular, it quickly
reaches a single-language state, albeit some details of the dynamics are
different from the complete-graph version. In some other cases, the preference
toward successfully communicating agents becomes much more relevant and the
model gets trapped in a multi-language regime. In this case gradual coarsening
and extinction of languages lead to the emergence of a dominant language,
albeit with some other languages still being present. A comparison of
distribution of languages in our model and in the human population is
discussed.Comment: 22 pages, accepted in Artificial Lif
A qualitative study exploring the difficulties influencing decision making at the end of life for people with dementia
BACKGROUND: Dementia is a progressive neurodegenerative condition characterized by declining functional and cognitive abilities. The quality of end of life care for people with dementia in the UK can be poor. Several difficult decisions may arise at the end of life, relating to the care of the person with dementia, for example management of comorbidities. OBJECTIVE: To explore difficulties in decision making for practitioners and family carers at the end of life for people with dementia. DESIGN: Qualitative methodology using focus groups and semi-structured interviews and thematic analysis methods. SETTINGS AND PARTICIPANTS: Former (n=4) and current (n=6) family carers of people with experience of end of life care for a person with dementia were recruited from an English dementia voluntary group in 2015. A further 24 health and care professionals were purposively sampled to include a broad range of expertise and experience in dementia end of life care. RESULTS: Four key themes were identified as follows: challenges of delivering coherent care in dynamic systems; uncertainty amongst decision makers; internal and external conflict amongst decision makers; and a lack of preparedness for the end of life. Overarching difficulties such as poor communication, uncertainty and conflict about the needs of the person with dementia as well as the decision maker's own role can characterize decision making at the end of life. CONCLUSIONS: This study suggests that decision making at the end of life for people with dementia has the potential to be improved. More planning earlier in the course of dementia with an on-going approach to conversation may increase preparedness and family carers' expectations of end of life
Managing uncertainty in care for people with dementia at the end of life: the use of heuristics
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