6,446 research outputs found
Ginzburg - Landau equation from SU(2) gauge field theory
The dual superconductor picture of the QCD vacuum is thought to describe
various aspects of the strong interaction including confinement. Ordinary
superconductivity is described by the Ginzburg-Landau (GL) equation. In the
present work we show that it is possible to arrive at a GL-like equation from
pure SU(2) gauge theory. This is accomplished by using Abelian projection to
split the SU(2) gauge fields into an Abelian subgroup and its coset. The two
gauge field components of the coset part act as the effective, complex, scalar
field of the GL equation. The Abelian part of the SU(2) gauge field is then
analogous to the electromagnetic potential in the GL equation. An important
aspect of the dual superconducting model is for the GL Lagrangian to have a
spontaneous symmetry breaking potential, and the existence of Nielsen-Olesen
flux tube solutions. Both of these require a tachyonic mass for the effective
scalar field. Such a tachyonic mass term is obtained from the condensation of
ghost fields.Comment: 7 pages, LATE
The energy partitioning of non-thermal particles in a plasma: or the Coulomb logarithm revisited
The charged particle stopping power in a highly ionized and weakly to
moderately coupled plasma has been calculated to leading and next-to-leading
order by Brown, Preston, and Singleton (BPS). After reviewing the main ideas
behind this calculation, we use a Fokker-Planck equation derived by BPS to
compute the electron-ion energy partitioning of a charged particle traversing a
plasma. The motivation for this application is ignition for inertial
confinement fusion -- more energy delivered to the ions means a better chance
of ignition, and conversely. It is therefore important to calculate the
fractional energy loss to electrons and ions as accurately as possible, as this
could have implications for the Laser Megajoule (LMJ) facility in France and
the National Ignition Facility (NIF) in the United States. The traditional
method by which one calculates the electron-ion energy splitting of a charged
particle traversing a plasma involves integrating the stopping power dE/dx.
However, as the charged particle slows down and becomes thermalized into the
background plasma, this method of calculating the electron-ion energy splitting
breaks down. As a result, the method suffers a systematic error of order T/E0,
where T is the plasma temperature and E0 is the initial energy of the charged
particle. In the case of DT fusion, for example, this can lead to uncertainties
as high as 10% or so. The formalism presented here is designed to account for
the thermalization process, and in contrast, it provides results that are
near-exact.Comment: 10 pages, 3 figures, invited talk at the 35th European Physical
Society meeting on plasma physic
Ascent from the lunar surface
Ascent from lunar surface problem with solution by variational calculu
Major surgery during the coronavirus-19 pandemic - patients' experiences
The SARS-Cov2 (COVID-19) pandemic has led to considerable change to the care of patients requiring major surgery in the UK. The rapid changes that were required to perioperative services were unprecedented in their scale, speed of implementation, and impact on staff, patients and the wider healthcare service. The implemented changes are largely unevaluated, particularly qualitatively, and from a patient perspective. Using qualitative methods, this study will aim to gain an understanding of patients’ experiences of the perioperative care provided during the pandemic. As a result of the pace of change, usual mechanisms for co-production with patients were largely swept aside. The findings of this study will be useful in identifying changes in the perioperative service that have been beneficial to patients. It is hoped that the results of this study will help in creating a framework that can be used by other institutions to enhance perioperative care pathways in the COVID-19 era and beyond. The study will also identify strategies that can be used within the NHS to support patient involvement in rapid chang
Management as a Liberal Art? Exploring the Connections
Essay exploring Peter Drucker\u27s claim for the field of management as a liberal art, comparing his writing with works on liberal education by John Henry Newman and Martha Nussbaum, and drawing upon examples of management practice from C. William Pollard of ServiceMaster
Preparing Decision Useful Financial Reports: A Challenge for Small Businesses*
Small business owners and managers want financial reports which are useful for their own decision-making purposes as well as for fairly presenting their business to others. Accountants and auditors consistently state that financial reports are the product of management. These statements being true, small business administrators should know what constitutes fair and useful financial presentation and how to achieve those characteristics.Accounting offers many alternatives for the treatment of financial events ( e.g., FIFO/UFO; Straight-line/ Declining Balance ). Alternatives are available in order to allow management most fairly and most usefully to present its financial reports. The characteristics which contribute to the decision usefulness of accounting information has been provided by the Financial Accounting Standards Board ( FASB ). and the FASB expects these characteristics to be considered in all financial statement preparations. However, the FASH has given no guidance for the consideration of the characteristics.This paper offers small business administrators a rational process for systematically choosing between accounting alternative methods. The procedure is easy to understand and simple to execute. It incorporates and utilizes the characteristics which the FASB states contribute to the decision usefulness of accounting information
The C Terminus of Ku80 activates the DNA-dependent protein kinase catalytic subunit
Ku is a heterodimeric protein with double-stranded DNA end-binding activity that operates in the process of nonhomologous end joining. Ku is thought to target the DNA-dependent protein kinase (DNA-PK) complex to the DNA and, when DNA bound, can interact and activate the DNA-PK catalytic subunit (DNA-PKcs). We have carried out a 3′ deletion analysis of Ku80, the larger subunit of Ku, and shown that the C-terminal 178 amino acid residues are dispensable for DNA end-binding activity but are required for efficient interaction of Ku with DNA-PKcs. Cells expressing Ku80 proteins that lack the terminal 178 residues have low DNA-PK activity, are radiation sensitive, and can recombine the signal junctions but not the coding junctions during V(D)J recombination. These cells have therefore acquired the phenotype of mouse SCID cells despite expressing DNA-PKcs protein, suggesting that an interaction between DNA-PKcs and Ku, involving the C-terminal region of Ku80, is required for DNA double-strand break rejoining and coding but not signal joint formation. To gain further insight into important domains in Ku80, we report a point mutational change in Ku80 in the defective xrs-2 cell line. This residue is conserved among species and lies outside of the previously reported Ku70-Ku80 interaction domain. The mutational change nonetheless abrogates the Ku70-Ku80 interaction and DNA end-binding activity
Inadequacies in the conventional treatment of the radiation field of moving sources
There is a fundamental difference between the classical expression for the
retarded electromagnetic potential and the corresponding retarded solution of
the wave equation that governs the electromagnetic field. While the boundary
contribution to the retarded solution for the {\em potential} can always be
rendered equal to zero by means of a gauge transformation that preserves the
Lorenz condition, the boundary contribution to the retarded solution of the
wave equation governing the {\em field} may be neglected only if it diminishes
with distance faster than the contribution of the source density in the far
zone. In the case of a source whose distribution pattern both rotates and
travels faster than light {\em in vacuo}, as realized in recent experiments,
the boundary term in the retarded solution governing the field is by a factor
of the order of {\em larger} than the source term of this solution in
the limit that the distance of the boundary from the source tends to
infinity. This result is consistent with the prediction of the retarded
potential that part of the radiation field generated by a rotating superluminal
source decays as , instead of , a prediction that is
confirmed experimentally. More importantly, it pinpoints the reason why an
argument based on a solution of the wave equation governing the field in which
the boundary term is neglected (such as appears in the published literature)
misses the nonspherical decay of the field
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The Stac Fada “impact ejecta” layer: not what it seems
The Stac Fada Member (SFM) forms part of the Stoer Group of the Torridonian of NW Scotland. The SFM is unique in the Torridonian, being characterized by the presence of greenish altered glass clasts. Its origin has been debated for decades with several hypotheses being proposed but all invoking some connection with volcanic activity in the region. More recently, Amor et al. suggested that the SFM represents “a chord section through the continuous ejecta blanket surrounding an impact crater”. Here, we confirm the presence of shocked material within the SFM and then discuss its origin
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