20,707 research outputs found
Dynamical error bounds for continuum discretisation via Gauss quadrature rules, -- a Lieb-Robinson bound approach
Instances of discrete quantum systems coupled to a continuum of oscillators
are ubiquitous in physics. Often the continua are approximated by a discrete
set of modes. We derive analytical error bounds on expectation values of system
observables that have been time evolved under such discretised Hamiltonians.
These bounds take on the form of a function of time and the number of discrete
modes, where the discrete modes are chosen according to Gauss quadrature rules.
The derivation makes use of tools from the field of Lieb-Robinson bounds and
the theory of orthonormal polynominals.Comment: 12 pages + 14 pages of proofs and appendices, Journal of Mathematical
Physics, Vol.57, Issue 2 (2016)
http://scitation.aip.org/content/aip/journal/jmp/57/2/10.1063/1.494043
The needs of people with dementia living at home from user, caregiver and professional perspectives: a cross-sectional survey
Few reports have been published about differences in perspectives on perceived needs among community-residing people with dementia, their family caregivers, and professionals. The aim of this study was to compare these perspectives
A time dependent relation between EUV solar flare light-curves from lines with differing formation temperatures
Extreme ultraviolet (EUV) solar flare emissions evolve in time as the
emitting plasma heats and then cools. Although accurately modeling this
evolution has been historically difficult, especially for empirical
relationships, it is important for understanding processes at the Sun, as well
as for their influence on planetary atmospheres. With a goal to improve
empirical flare models, a new simple empirical expression is derived to predict
how cool emissions will evolve based on the evolution of a hotter emission.
This technique is initially developed by studying 12 flares in detail observed
by the EUV Variability Experiment (EVE) onboard the Solar Dynamics Observatory
(SDO). Then, over 1100 flares observed by EVE are analyzed to validate these
relationships. The Cargill and Enthalpy Based Thermal Evolution of Loops
(EBTEL) flare cooling models are used to show that this empirical relationship
implies the energy radiated by a population of hotter formed ions is
approximately proportional to the energy exciting a population of cooler formed
ions emitting when the peak formation temperatures of the two lines are up to
72% of each other and above 2 MK. These results have practical implications for
improving flare irradiance empirical modeling and for identifying key emission
lines for future monitoring of flares for space weather operations; and also
provide insight into the cooling processes of flare plasma.Comment: Final version accepted for publication by the Journal of Space
Weather and Space Climate on 23 November 201
Probing the birth of fast rotating magnetars through high-energy neutrinos
We investigate the high-energy neutrino emission expected from newly born
magnetars surrounded by their stellar ejecta. Protons might be accelerated up
to 0.1-100 EeV energies possibly by, e.g., the wave dissipation in the winds,
leading to hadronic interactions in the stellar ejecta. The resulting PeV-EeV
neutrinos can be detected by IceCube/KM3Net with a typical peak time scale of a
few days after the birth of magnetars, making the characteristic soft-hard-soft
behavior. Detections would be important as a clue to the formation mechanism of
magnetars, although there are ambiguities coming from uncertainties of several
parameters such as velocity of the ejecta. Non-detections would also lead to
useful constraints on the scenario.Comment: 5 pages, 3 figures, accepted for publication in PR
Regenerative CO2 removal for PLSS application
Various concepts for the design of the nonelectrochemical absorber were defined and evaluated. A preliminary design based on the use of hollow fiber membranes was developed. Small scale bench testing demonstrated the carbon dioxide removal capability and provided design data for scale-up to the one person level. A full scale conceptual design of the absorbent regeneration hardware using six electrochemical cells was also completed. The design was supported by single cell testing and showed that a full scale regeneration system, operating continuously over 24 hours, can regenerate the absorbent from one extravehicular activity mission. The single cell regeneration hardware was operated for over 800 hours
A History of Fort Larned
This thesis is a study of the history of Fort Larned Kansas covering the years 1859-1932
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