83 research outputs found
Spin-2 spectrum of defect theories
We study spin-2 excitations in the background of the recently-discovered
type-IIB solutions of D'Hoker et al. These are holographically-dual to defect
conformal field theories, and they are also of interest in the context of the
Karch-Randall proposal for a string-theory embedding of localized gravity. We
first generalize an argument by Csaki et al to show that for any solution with
four-dimensional anti-de Sitter, Poincare or de Sitter invariance the spin-2
excitations obey the massless scalar wave equation in ten dimensions. For the
interface solutions at hand this reduces to a Laplace-Beltrami equation on a
Riemann surface with disk topology, and in the simplest case of the
supersymmetric Janus solution it further reduces to an ordinary differential
equation known as Heun's equation. We solve this equation numerically, and
exhibit the spectrum as a function of the dilaton-jump parameter .
In the limit of large a nearly-flat linear-dilaton dimension grows
large, and the Janus geometry becomes effectively five-dimensional. We also
discuss the difficulties of localizing four-dimensional gravity in the more
general backgrounds with NS5-brane or D5-brane charge, which will be analyzed
in detail in a companion paper.Comment: 41 pages, 6 figure
The Immunological Synapse: a Dynamic Platform for Local Signaling
The immunological synapse (IS) as a concept has evolved from a static view of the junction between T cells and their antigen-presenting cell partners. The entire process of IS formation and extinction is now known to entail a dynamic reorganization of membrane domains and proteins within and adjacent to those domains. Discussion The entire process is also intricately tied to the motility machineryâboth as that machinery directs âscanningâ prior to T-cell receptor engagement and as it is appropriated during the ongoing developments at the IS. While the synapse often remains dynamic in order to encourage surveillance of new antigen-presenting surfaces, cytoskeletal forces also regulate the development of signals, likely including the assembly of ion channels. In both neuronal and immunological synapses, localized Ca 2+ signals and accumulation or depletion of ions in microdomains accompany the concentration of signaling molecules in the synapse. Such spatiotemporal signaling in the synapse greatly accelerates kinetics and provides essential checkpoints to validate effective cellâcell communication
Multiple and Multidimensional life transitions in the context of life-limiting health conditions:Longitudinal study focussing on perspectives of Young Adults, Families and Professionals
Background:
There is a dearth of literature that investigates life transitions of young adults (YAs) with life-limiting conditions, families and professionals. The scant literature that is available has methodological limitations, including not listening to the voice of YAs, collecting data retrospectively, at one time point, from one groupâs perspective and single case studies. The aim of this study was to address the gaps found in our literature review and provide a clearer understanding of the multiple and multi-dimensional life transitions experienced by YAs and significant others, over a period of time.
Methods:
This qualitative study used a longitudinal design and data were collected using semi-structured interviews over a 6-month period at 3 time points. Participants included 12 YAs with life-limiting conditions and their nominated significant others (10 family members and 11 professionals). Data were analysed using a thematic analysis approach.
Results:
Life transitions of YA and significant others are complex; they experience multiple and multi-dimensional transitions across several domains. The findings challenge the notion that all life transitions are triggered by health transitions of YAs, and has highlighted environmental factors (attitudinal and systemic) that can be changed to facilitate smoother transitions in various aspects of their lives.
Conclusions:
This study makes a unique and significant contribution to literature. It provides evidence and rich narratives for policy makers and service providers to change policies and practices that are in line with the needs of YAs with life-limiting conditions as they transition to adulthood. Families and professionals have specific training needs that have not yet been met fully
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