6,542 research outputs found
Tricritical Point in Quantum Phase Transitions of the Coleman-Weinberg Model at Higgs Mass
The tricritical point, which separates first and second order phase
transitions in three-dimensional superconductors, is studied in the
four-dimensional Coleman-Weinberg model, and the similarities as well as the
differences with respect to the three-dimensional result are exhibited. The
position of the tricritical point in the Coleman-Weinberg model is derived and
found to be in agreement with the Thomas-Fermi approximation in the
three-dimensional Ginzburg-Landau theory. From this we deduce a special role of
the tricritical point for the Standard Model Higgs sector in the scope of the
latest experimental results, which suggests the unexpected relevance of
tricritical behavior in the electroweak interactions.Comment: 5 pages, 1 figure, published in Phys. Lett.
Acylindrical hyperbolicity of cubical small-cancellation groups
We provide an analogue of Strebel's classification of geodesic triangles in
classical groups for groups given by Wise's cubical presentations
satisfying sufficiently strong metric cubical small cancellation conditions.
Using our classification, we prove that, except in specific degenerate cases,
such groups are acylindrically hyperbolic.Comment: Added figures. Exposition improved in Section 3,
correction/simplification in Section 5, background added and citations
updated in Section
The Outburst of the Blazar AO 0235+164 in 2006 December: Shock-in-Jet Interpretation
We present the results of polarimetric ( band) and multicolor photometric
() observations of the blazar AO 0235+16 during an outburst in 2006
December. The data reveal a short timescale of variability (several hours),
which increases from optical to near-IR wavelengths; even shorter variations
are detected in polarization. The flux density correlates with the degree of
polarization, and at maximum degree of polarization the electric vector tends
to align with the parsec-scale jet direction. We find that a variable component
with a steady power-law spectral energy distribution and very high optical
polarization (30-50%) is responsible for the variability. We interpret these
properties of the blazar withina model of a transverse shock propagating down
the jet. In this case a small change in the viewing angle of the jet, by
, and a decrease in the shocked plasma compression by a factor of
1.5 are sufficient to account for the variability.Comment: 22 pages, 8 figures, accepted for Ap
Citations in a Cinch: From Bibliographies to Faculty Engagement
At Hope College, faculty are overwhelmed with the sheer number of places they must submit their publication information, including the institutional repository. A new project to generate citations for faculty chairs has been undertaken with two goals in mind: 1) create bibliographies for departments to use in annual reports, and 2) establish DC as the go-to place to find out what faculty have accomplished in the last year on campus, thereby eliminating the need to submit publication information elsewhere. The goals of this poster are to show the workflow of creating citations, how I worked with bepress to get what we need out of the citations, and report on the progress of how this process benefits the repository and the campus as a whole
A simple and efficient numerical scheme to integrate non-local potentials
As nuclear wave functions have to obey the Pauli principle, potentials issued
from reaction theory or Hartree-Fock formalism using finite-range interactions
contain a non-local part. Written in coordinate space representation, the
Schrodinger equation becomes integro-differential, which is difficult to solve,
contrary to the case of local potentials, where it is an ordinary differential
equation. A simple and powerful method has been proposed several years ago,
with the trivially equivalent potential method, where non-local potential is
replaced by an equivalent local potential, which is state-dependent and has to
be determined iteratively. Its main disadvantage, however, is the appearance of
divergences in potentials if the wave functions have nodes, which is generally
the case. We will show that divergences can be removed by a slight modification
of the trivially equivalent potential method, leading to a very simple, stable
and precise numerical technique to deal with non-local potentials. Examples
will be provided with the calculation of the Hartree-Fock potential and
associated wave functions of 16O using the finite-range N3LO realistic
interaction.Comment: 8 pages, 2 figures, submitted to Eur. Phys. J.
PROPEL: implementation of an evidence based pelvic floor muscle training intervention for women with pelvic organ prolapse: a realist evaluation and outcomes study protocol
Abstract Background Pelvic Organ Prolapse (POP) is estimated to affect 41%â50% of women aged over 40. Findings from the multi-centre randomised controlled âPelvic Organ Prolapse PhysiotherapYâ (POPPY) trial showed that individualised pelvic floor muscle training (PFMT) was effective in reducing symptoms of prolapse, improved quality of life and showed clear potential to be cost-effective. However, provision of PFMT for prolapse continues to vary across the UK, with limited numbers of womenâs health physiotherapists specialising in its delivery. Implementation of this robust evidence from the POPPY trial will require attention to different models of delivery (e.g. staff skill mix) to fit with differing care environments. Methods A Realist Evaluation (RE) of implementation and outcomes of PFMT delivery in contrasting NHS settings will be conducted using multiple case study sites. Involving substantial local stakeholder engagement will permit a detailed exploration of how local sites make decisions on how to deliver PFMT and how these lead to service change. The RE will track how implementation is working; identify what influences outcomes; and, guided by the RE-AIM framework, will collect robust outcomes data. This will require mixed methods data collection and analysis. Qualitative data will be collected at four time-points across each site to understand local contexts and decisions regarding options for intervention delivery and to monitor implementation, uptake, adherence and outcomes. Patient outcome data will be collected at baseline, six months and one year follow-up for 120 women. Primary outcome will be the Pelvic Organ Prolapse Symptom Score (POP-SS). An economic evaluation will assess the costs and benefits associated with different delivery models taking account of further health care resource use by the women. Cost data will be combined with the primary outcome in a cost effectiveness analysis, and the EQ-5D-5L data in a cost utility analysis for each of the different models of delivery. Discussion Study of the implementation of varying models of service delivery of PFMT across contrasting sites combined with outcomes data and a cost effectiveness analysis will provide insight into the implementation and value of different models of PFMT service delivery and the cost benefits to the NHS in the longer term
Can Light Echoes Account for the Slow Decay of Type IIn Supernovae?
The spectra of type IIn supernovae indicate the presence of apre-existing
slow, dense circumstellar wind (CSW). If the CSW extends sufficiently far from
the progenitor star, then dust formation should occur in the wind. The light
from the supernova explosion will scatter off this dust and produce a light
echo. Continuum emission seen after the peak will have contributions from both
this echo as well as from the shock of the ejecta colliding with the CSW, with
a fundamental question of which source dominates the continuum. We calculate
the brightness of the light echo as a function of time for a range of dust
shell geometries, and use our calculations to fit to the light curves of SN
1988Z and SN 1997ab, the two slowest declining IIn supernovae on record. We
find that the light curves of both objects can be reproduced by the echo model.
However, their rate of decay from peak, color at peak and their observed peak
absolute magnitudes when considered together are inconsistent with the echo
model. Furthermore, when the observed values of M are corrected for the
effects of dust scattering, the values obtained imply that these supernovae
have unrealistically high luminosities. We conclude that light echoes cannot
properly account for the slow decline seen in some IIn's, and that the shock
interaction is likely to dominate the continuum emission.Comment: 15 pages, 9 figure
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