5,260 research outputs found
Solitary Waves in Discrete Media with Four Wave Mixing
In this paper, we examine in detail the principal branches of solutions that
arise in vector discrete models with nonlinear inter-component coupling and
four wave mixing. The relevant four branches of solutions consist of two single
mode branches (transverse electric and transverse magnetic) and two mixed mode
branches, involving both components (linearly polarized and elliptically
polarized). These solutions are obtained explicitly and their stability is
analyzed completely in the anti-continuum limit (where the nodes of the lattice
are uncoupled), illustrating the supercritical pitchfork nature of the
bifurcations that give rise to the latter two, respectively, from the former
two. Then the branches are continued for finite coupling constructing a full
two-parameter numerical bifurcation diagram of their existence. Relevant
stability ranges and instability regimes are highlighted and, whenever
unstable, the solutions are dynamically evolved through direct computations to
monitor the development of the corresponding instabilities. Direct connections
to the earlier experimental work of Meier et al. [Phys. Rev. Lett. {\bf 91},
143907 (2003)] that motivated the present work are given.Comment: 13 pages, 10 figure
Vortex Structures Formed by the Interference of Sliced Condensates
We study the formation of vortices, vortex necklaces and vortex ring
structures as a result of the interference of higher-dimensional Bose-Einstein
condensates (BECs). This study is motivated by earlier theoretical results
pertaining to the formation of dark solitons by interfering quasi
one-dimensional BECs, as well as recent experiments demonstrating the formation
of vortices by interfering higher-dimensional BECs. Here, we demonstrate the
genericity of the relevant scenario, but also highlight a number of additional
possibilities emerging in higher-dimensional settings. A relevant example is,
e.g., the formation of a "cage" of vortex rings surrounding the
three-dimensional bulk of the condensed atoms. The effects of the relative
phases of the different BEC fragments and the role of damping due to coupling
with the thermal cloud are also discussed. Our predictions should be
immediately tractable in currently existing experimental BEC setups.Comment: 8 pages, 6 figures (low res). To appear in Phys. Rev. A. Full
resolution preprint available at:
http://www-rohan.sdsu.edu/~rcarrete/publications
CMOS output buffer wave shaper
As the switching speeds and densities of Digital CMOS integrated circuits continue to increase, output switching noise becomes more of a problem. A design technique which aids in the reduction of switching noise is reported. The output driver stage is analyzed through the use of an equivalent RLC circuit. The results of the analysis are used in the design of an output driver stage. A test circuit based on these techniques is being submitted to MOSIS for fabrication
The clinical application of PET/CT: a contemporary review
The combination of positron emission tomography (PET) scanners and x-ray computed tomography (CT) scanners into a single PET/CT scanner has resulted in vast improvements in the diagnosis of disease, particularly in the field of oncology. A decade on from the publication of the details of the first PET/CT scanner, we review the technology and applications of the modality. We examine the design aspects of combining two different imaging types into a single scanner, and the artefacts produced such as attenuation correction, motion and CT truncation artefacts. The article also provides a discussion and literature review of the applications of PET/CT to date, covering detection of tumours, radiotherapy treatment planning, patient management, and applications external to the field of oncology
Fabricación de ladrillos y tejas a partir de caliza
Not availableLa fabricación de ladrillos y tejas, a base de caliza, ha alcanzado un gran desarrollo en Cuba. La mayorÃa de los ladrillos corrientes que se producen en la zona de La Habana se fabrican a partir de una caliza, ligeramente plástica, con más de un 90% de CaCO3 se le suele añadir un 10% de arcilla roja, con el fin de conseguir un ligero color amarillento y elevar la resistencia de los ladrillos. El moldeo se realiza por extrusión
Investigations of the lunar surface
Scientific programs concerned with investigations of the lunar surface are described along with some results. These include lunar photographs and map collection program, crater measuring and depth calculation (earthside and farside), Schroeter's valley model, and the 61-inch color filter photography. Several graphs and maps of the lunar surface are present along with a method used for depth calculation
Care staff and family member perspectives on quality of life in people with very severe dementia in long-term care: a cross-sectional study.
This is the final version of the article. Available from the publisher via the DOI in this record.BACKGROUND: Little is known about the quality of life of people with very severe dementia in long-term care settings, and more information is needed about the properties of quality of life measures aimed at this group. In this study we explored the profiles of quality of life generated through proxy ratings by care staff and family members using the Quality of Life in Late-stage Dementia (QUALID) scale, examined factors associated with these ratings, and further investigated the psychometric properties of the QUALID. METHODS: Proxy ratings of quality of life using the QUALID were obtained for 105 residents with very severe dementia, categorised as meeting criteria for Functional Assessment Staging (FAST) stages 6 or 7, from members of care staff (n = 105) and family members (n = 73). A range of resident and staff factors were also assessed. RESULTS: Care staff and family member ratings were similar but were associated with different factors. Care staff ratings were significantly predicted by resident mood and awareness/responsiveness. Family member ratings were significantly predicted by use of antipsychotic medication. Factor analysis of QUALID scores suggested a two-factor solution for both care staff ratings and family member ratings. CONCLUSIONS: The findings offer novel evidence about predictors of care staff proxy ratings of quality of life and demonstrate that commonly-assessed resident variables explain little of the variability in family members' proxy ratings. The findings provide further information about the psychometric properties of the QUALID, and support the applicability of the QUALID as a means of examining quality of life in very severe dementia.LC: Higher Education Funding Council for Wales.
CQ: National Institute for Social Care and Health Research and Economic & Social Research Council/ National Institute for Health Research.
ZH: National Institute for Social Care and Health Research.
RW: National Institute for Social Care and Health Research.
RTW: Higher Education Funding Council for Wale
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