2,619 research outputs found
On the degeneracies of the mass-squared differences for three-neutrino oscillations
Using an algebraic formulation, we explore two well-known degeneracies
involving the mass-squared differences for three-neutrino oscillations assuming
CP symmetry is conserved. For vacuum oscillation, we derive the expression for
the mixing angles that permit invariance under the interchange of two
mass-squared differences. This symmetry is most easily expressed in terms of an
ascending mass order. This can be used to reduce the parameter space by one
half in the absence of the MSW effect. For oscillations in matter, we derive
within our formalism the known approximate degeneracy between the standard and
inverted mass hierarchies in the limit of vanishing . This is done
with a mass ordering that permits the map .
Our techniques allow us to translate mixing angles in this mass order
convention into their values for the ascending order convention. Using this
dictionary, we demonstrate that the vacuum symmetry and the approximate
symmetry invoked for oscillations in matter are distinctly different.Comment: 5 pages, revised manuscrip
Station coordinates in the standard earth 3 system and radiation-pressure perturbations from ISAGEX camera data
Simultaneous and individual camera observations of GEOS 1, GEOS 2, Pageos, and Midas 4 obtained during the International Satellite Geodesy Experiment are utilized to determine station coordinates. The Smithsonian Astrophysical Observatory Standard Earth III system of coordinates is used to tie the geometrical network to a geocentric system and as a reference for calculating satellite orbits. A solution for coordinates combining geometrical and dynamical methods is obtained, and a comparison between the solutions and terrestrial data is made. The radiation-pressure and earth-albedo perturbations for Pageos are very large, and Pageos' orbits are used to evaluate the analytical treatment of these perturbations. Residual effects, which are probably of interest to aeronomists, remain in the Pageos orbits
Constitutional Conversations
This paper examines two cases that raise questions about the capacity to secure redress for the limitation of Charter rights through litigation. It gives expression to a certain litigation fatigue stemming from processes of litigation and then legislative or practice reform that at times feel dysfunctional. While the to and fro between the courts and state actors has sometimes been described as a “dialogue”, this paper does not weigh in on the question of whether dialogue theory legitimates judicial review. It focuses instead on a consideration of a prerequisite to a functional constitutional conversation. A functional constitutional conversation would build on the insights of both speakers and thereby lean towards rights recognition and access to justice
A Positive Future for Section 7?: Children and Charter Change
It has been more than a decade since Justice Arbour’s dissenting judgment in Gosselin, the first and only Supreme Court of Canada judgment recognizing positive rights under section 7. The jurisprudence that has developed in the intervening years presents some challenges to pursuing such a claim today. Yet the author offers the view that because of the special vulnerability of children, their capacity for development and the state’s treatment of children in other contexts, recognition of positive rights for children is consistent with Canada’s legal/political traditions, current laws and jurisprudence. Childhood, the refore, may well be the “special circumstance” necessary to push positive section 7 rights forward under the Charter. In light of the growing disparities in wealth in Canada, and the link between poverty and the ability to meet a child’s basic needs, such an outcome is urgently needed in the interests of justice to ensure that all children eventually have an equal opportunity to be involved in society’s most important institutions, which ultimately control distribution of wealth, goods and opportunity
A Positive Future for Section 7?: Children and Charter Change
It has been more than a decade since Justice Arbour’s dissenting judgment in Gosselin, the first and only Supreme Court of Canada judgment recognizing positive rights under section 7. The jurisprudence that has developed in the intervening years presents some challenges to pursuing such a claim today. Yet the author offers the view that because of the special vulnerability of children, their capacity for development and the state’s treatment of children in other contexts, recognition of positive rights for children is consistent with Canada’s legal/political traditions, current laws and jurisprudence. Childhood, the refore, may well be the “special circumstance” necessary to push positive section 7 rights forward under the Charter. In light of the growing disparities in wealth in Canada, and the link between poverty and the ability to meet a child’s basic needs, such an outcome is urgently needed in the interests of justice to ensure that all children eventually have an equal opportunity to be involved in society’s most important institutions, which ultimately control distribution of wealth, goods and opportunity
Realization of Artificial Ice Systems for Magnetic Vortices in a Superconducting MoGe Thin-film with Patterned Nanostructures
We report an anomalous matching effect in MoGe thin films containing pairs of
circular holes arranged in such a way that four of those pairs meet at each
vertex point of a square lattice. A remarkably pronounced fractional matching
was observed in the magnetic field dependences of both the resistance and the
critical current. At the half matching field the critical current can be even
higher than that at zero field. This has never been observed before for
vortices in superconductors with pinning arrays. Numerical simulations within
the nonlinear Ginzburg-Landau theory reveal a square vortex ice configuration
in the ground state at the half matching field and demonstrate similar
characteristic features in the field dependence of the critical current,
confirming the experimental realization of an artificial ice system for
vortices for the first time.Comment: To appear in Phys. Rev. Let
Modeling large scale species abundance with latent spatial processes
Modeling species abundance patterns using local environmental features is an
important, current problem in ecology. The Cape Floristic Region (CFR) in South
Africa is a global hot spot of diversity and endemism, and provides a rich
class of species abundance data for such modeling. Here, we propose a
multi-stage Bayesian hierarchical model for explaining species abundance over
this region. Our model is specified at areal level, where the CFR is divided
into roughly one minute grid cells; species abundance is observed at
some locations within some cells. The abundance values are ordinally
categorized. Environmental and soil-type factors, likely to influence the
abundance pattern, are included in the model. We formulate the empirical
abundance pattern as a degraded version of the potential pattern, with the
degradation effect accomplished in two stages. First, we adjust for land use
transformation and then we adjust for measurement error, hence
misclassification error, to yield the observed abundance classifications. An
important point in this analysis is that only of the grid cells have been
sampled and that, for sampled grid cells, the number of sampled locations
ranges from one to more than one hundred. Still, we are able to develop
potential and transformed abundance surfaces over the entire region. In the
hierarchical framework, categorical abundance classifications are induced by
continuous latent surfaces. The degradation model above is built on the latent
scale. On this scale, an areal level spatial regression model was used for
modeling the dependence of species abundance on the environmental factors.Comment: Published in at http://dx.doi.org/10.1214/10-AOAS335 the Annals of
Applied Statistics (http://www.imstat.org/aoas/) by the Institute of
Mathematical Statistics (http://www.imstat.org
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Local forest structure variability increases resilience to wildfire in dry western U.S. coniferous forests.
A 'resilient' forest endures disturbance and is likely to persist. Resilience to wildfire may arise from feedback between fire behaviour and forest structure in dry forest systems. Frequent fire creates fine-scale variability in forest structure, which may then interrupt fuel continuity and prevent future fires from killing overstorey trees. Testing the generality and scale of this phenomenon is challenging for vast, long-lived forest ecosystems. We quantify forest structural variability and fire severity across >30 years and >1000 wildfires in California's Sierra Nevada. We find that greater variability in forest structure increases resilience by reducing rates of fire-induced tree mortality and that the scale of this effect is local, manifesting at the smallest spatial extent of forest structure tested (90 × 90 m). Resilience of these forests is likely compromised by structural homogenisation from a century of fire suppression, but could be restored with management that increases forest structural variability
Measuring the mass of a sterile neutrino with a very short baseline reactor experiment
An analysis of the world's neutrino oscillation data, including sterile
neutrinos, (M. Sorel, C. M. Conrad, and M. H. Shaevitz, Phys. Rev. D 70,
073004) found a peak in the allowed region at a mass-squared difference eV. We trace its origin to harmonic oscillations in the
electron survival probability as a function of L/E, the ratio of
baseline to neutrino energy, as measured in the near detector of the Bugey
experiment. We find a second occurrence for eV. We
point out that the phenomenon of harmonic oscillations of as a
function of L/E, as seen in the Bugey experiment, can be used to measure the
mass-squared difference associated with a sterile neutrino in the range from a
fraction of an eV to several eV (compatible with that indicated by the
LSND experiment), as well as measure the amount of electron-sterile neutrino
mixing. We observe that the experiment is independent, to lowest order, of the
size of the reactor and suggest the possibility of a small reactor with a
detector sitting at a very short baseline.Comment: 4 pages, 2 figure
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