21,544 research outputs found
Multipole expansion at the level of the action
Sources of long wavelength radiation are naturally described by an effective
field theory (EFT) which takes the form of a multipole expansion. Its action is
given by a derivative expansion where higher order terms are suppressed by
powers of the ratio of the size of the source over the wavelength. In order to
determine the Wilson coefficients of the EFT, i.e. the multipole moments, one
needs the mapping between a linear source term action and the multipole
expansion form of the action of the EFT. In this paper we perform the multipole
expansion to all orders by Taylor expanding the field in the source term and
then decomposing the action into symmetric trace free tensors which form
irreducible representations of the rotation group. We work at the level of the
action, and we obtain the action to all orders in the multipole expansion and
the exact expressions for the multipole moments for a scalar field,
electromagnetism and linearized gravity. Our results for the latter two cases
are manifestly gauge invariant. We also give expressions for the energy flux
and the (gauge dependent) radiation field to all orders in the multipole
expansion. The results for linearized gravity are a component of the EFT
framework NRGR and will greatly simplify future calculations of gravitational
wave observables in the radiation sector of NRGR.Comment: 39 pages, some typos corrected, published versio
Systems Integration for the Kennedy Space Center (KSC) Robotics Applications Development Laboratory (RADL)
Robotics technology is a rapidly advancing field moving from applications on repetitive manufacturing processes toward applications of more variable and complex tasks. Current directions of NASA designs for the Space Station and other future spacecraft is moving toward the use of robotics for operational, maintenance and repair functions while the spacecraft is in orbit. These spacecraft systems will eventually require processing through KSC for launch and refurbishment.
In the future, KSC will be called on to design ground processing facilities for new generation launch vehicles such as the Heavy Lift Launch Vehicle and the Second Generation Shuttle. The design of these facilities should take advantage of stateof- the-art robotics technology to provide the most efficient and effective vehicle processing.
In addition to these future needs for robotics technology expertise, it is readily apparent that robotics technology could also have near-term applications to some of the existing hazardous and repetitive Shuttle and payload processing activities at KSC
BlogForever D3.2: Interoperability Prospects
This report evaluates the interoperability prospects of the BlogForever platform. Therefore, existing interoperability models are reviewed, a Delphi study to identify crucial aspects for the interoperability of web archives and digital libraries is conducted, technical interoperability standards and protocols are reviewed regarding their relevance for BlogForever, a simple approach to consider interoperability in specific usage scenarios is proposed, and a tangible approach to develop a succession plan that would allow a reliable transfer of content from the current digital archive to other digital repositories is presented
Gravitational radiative corrections from effective field theory
In this paper we construct an effective field theory (EFT) that describes
long wavelength gravitational radiation from compact systems. To leading order,
this EFT consists of the multipole expansion, which we describe in terms of a
diffeomorphism invariant point particle Lagrangian. The EFT also systematically
captures "post-Minkowskian" corrections to the multipole expansion due to
non-linear terms in general relativity. Specifically, we compute long distance
corrections from the coupling of the (mass) monopole moment to the quadrupole
moment, including up to two mass insertions. Along the way, we encounter both
logarithmic short distance (UV) and long wavelength (IR) divergences. We show
that the UV divergences can be (1) absorbed into a renormalization of the
multipole moments and (2) resummed via the renormalization group. The IR
singularities are shown to cancel from properly defined physical observables.
As a concrete example of the formalism, we use this EFT to reproduce a number
of post-Newtonian corrections to the gravitational wave energy flux from
non-relativistic binaries, including long distance effects up to 3PN ()
order. Our results verify that the factorization of scales proposed in the NRGR
framework of Goldberger and Rothstein is consistent up to order 3PN.Comment: 37 pages, LaTeX. Published versio
Protocol for an HTA report: Does therapeutic writing help people with long-term conditions? Systematic review, realist synthesis and economic modelling
This article is made available through the Brunel Open Access Publishing Fund. This is an Open Access article distributed in accordance with the Creative Commons Attribution Non Commercial (CC BY-NC 3.0) license, which permits others to distribute, remix, adapt, build upon this work non-commercially, and license their derivative works on different terms, provided the original work is properly cited and the use is non-commercial. See: http://creativecommons.org/licenses/by-nc/3.0/Introduction: Long-term medical conditions (LTCs) cause reduced health-related quality of life and considerable health service expenditure. Writing therapy has potential to improve physical and mental health in people with LTCs, but its effectiveness is not established. This project aims to establish the clinical and cost-effectiveness of therapeutic writing in LTCs by systematic review and economic evaluation, and to evaluate context and mechanisms by which it might work, through realist synthesis.
Methods: Included are any comparative study of therapeutic writing compared with no writing, waiting list, attention control or placebo writing in patients with any diagnosed LTCs that report at least one of the following: relevant clinical outcomes; quality of life; health service use; psychological, behavioural or social functioning; adherence or adverse events. Searches will be conducted in the main medical databases including MEDLINE, EMBASE, PsycINFO, The Cochrane Library and Science Citation Index. For the realist review, further purposive and iterative searches through snowballing techniques will be undertaken. Inclusions, data extraction and quality assessment will be in duplicate with disagreements resolved through discussion. Quality assessment will include using Grading of Recommendations Assessment, Development and Evaluation (GRADE) criteria. Data synthesis will be narrative and tabular with meta-analysis where appropriate. De novo economic modelling will be attempted in one clinical area if sufficient evidence is available and performed according to the National Institute for Health and Care Excellence (NICE) reference case.National Institute for Health Research
Health Technology Assessment (NIHR HTA) Programm
Flight tests of IFR landing approach systems for helicopters
Joint NASA/FAA helicopter flight tests were conducted to investigate airborne radar approaches (ARA) and microwave landing system (MLS) approaches. Flight-test results were utilized to prove NASA with a data base to be used as a performance measure for advanced guidance and navigation concepts, and to provide FAA with data for establishment of TERPS criteria. The first flight-test investigation consisted of helicopter IFR approaches to offshore oil rigs in the Gulf of Mexico, using weather/mapping radar, operational pilots, and a Bell 212 helicopter. The second flight-test investigation consisted of IFR MLS approaches at Crows Landing (near Ames Research Center), with a Bell UH-1H helicopter, using NASA, FAA, and operational industry pilots. Tests are described and results discussed
The Vulnerability of Minority Homeowners in the Housing Boom and Bust
This paper examines mortgage outcomes for a large sample of individual home purchases and refinances linked to credit scores in seven major US markets. Among those with similar credit scores and loan attributes, black and Hispanic homeowners had much higher rates of delinquency and default in the downturn. These estimated differences are especially pronounced for loans originated near the peak of the housing boom. These findings suggest that black and Hispanic homeowners drawn into the market near the peak were especially vulnerable to adverse economic shocks and raise concerns about homeownership as a mechanism for reducing racial disparities in wealth
Creep feeding studies with lambs
This bulletin is a report on Department of Animal Husbandry Research Project 142, 'Method of Lamb Production'--P. [2].Digitized 2007 AES.Includes bibliographical references (page 16)
Solving the Effective Field Equations for the Newtonian Potential
Loop corrections to the gravitational potential are usually inferred from
scattering amplitudes, which seems quite different from how the linearized
Einstein equations are solved with a static, point mass to give the classical
potential. In this study we show how the Schwinger-Keldysh effective field
equations can be used to compute loop corrections to the potential in a way
which parallels the classical treatment. We derive explicit results for the one
loop correction from the graviton self-energy induced by a massless, minimally
coupled scalar.Comment: 15 pages, uses LaTeX2
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