17,664 research outputs found
Estimating Government Policy Preferences to Predict New Firm Formation
Entrepreneurship, Entrepreneurial Climate, Subsistance, Discretionary Spending, Community/Rural/Urban Development, Public Economics,
Dynamical N-body Equlibrium in Circular Dilaton Gravity
We obtain a new exact equilibrium solution to the N-body problem in a
one-dimensional relativistic self-gravitating system. It corresponds to an
expanding/contracting spacetime of a circle with N bodies at equal proper
separations from one another around the circle. Our methods are
straightforwardly generalizable to other dilatonic theories of gravity, and
provide a new class of solutions to further the study of (relativistic)
one-dimensional self-gravitating systems.Comment: 4 pages, latex, reference added, minor changes in wordin
Adapting Tests of Sign Language Assessment for Other Sign Languages—A Review of Linguistic, Cultural, and Psychometric Problems
Given the current lack of appropriate assessment tools for measuring deaf children's sign language skills, many test developers have used existing tests of other sign languages as templates to measure the sign language used by deaf people in their country. This article discusses factors that may influence the adaptation of assessment tests from one natural sign language to another. Two tests which have been adapted for several other sign languages are focused upon: the Test for American Sign Language and the British Sign Language Receptive Skills Test. A brief description is given of each test as well as insights from ongoing adaptations of these tests for other sign languages. The problems reported in these adaptations were found to be grounded in linguistic and cultural differences, which need to be considered for future test adaptations. Other reported shortcomings of test adaptation are related to the question of how well psychometric measures transfer from one instrument to another
Probing minimal supergravity in the type-I seesaw mechanism with lepton flavour violation at the CERN LHC
The most general supersymmetric seesaw mechanism has too many parameters to
be predictive and thus can not be excluded by any measurements of lepton
flavour violating (LFV) processes. We focus on the simplest version of the
type-I seesaw mechanism assuming minimal supergravity boundary conditions. We
compute branching ratios for the LFV scalar tau decays, , as well as loop-induced LFV decays at low energy, such as
and , exploring their sensitivity to the
unknown seesaw parameters. We find some simple, extreme scenarios for the
unknown right-handed parameters, where ratios of LFV branching ratios correlate
with neutrino oscillation parameters. If the overall mass scale of the left
neutrinos and the value of the reactor angle were known, the study of LFV
allows, in principle, to extract information about the so far unknown
right-handed neutrino parameters.Comment: 29 pages, 27 figures; added explanatory comments, corrected typos,
final version for publicatio
Lepton flavour violating stau decays versus seesaw parameters: correlations and expected number of events for both seesaw type-I and II
In minimal supergravity (mSugra), the neutrino sector is related to the
slepton sector by means of the renormalization group equations. This opens a
door to indirectly test the neutrino sector via measurements at the LHC.
Concretely, for the simplest seesaw type-I, we present the correlations between
seesaw parameters and ratio of stau lepton flavour violating (LFV) branching
ratios. We find some simple, extreme scenarios for the unknown right-handed
parameters, where ratios of LFV rates correlate with neutrino oscillation
parameters. On the other hand, we scan the mSugra parameter space, for both
seesaw type-I and II, to find regions where LFV stau decays can be maximized,
while respecting low-energy experimental bounds. We estimate the expected
number of events at the LHC for a sample luminosity of L = 100 fb^{-1}.Comment: 10 pages, 6 figures, 1 table, to appear in the proceedings of
DISCRETE'08 Symposium on Prospects in the Physics of Discrete Symmetries,
11-16 December 2008, Valencia, Spain; some comments adde
Neutrino texture saturating the CP asymmetry
We study a neutrino mass texture which can explain the neutrino oscillation
data and also saturate the upper bound of the CP asymmetry in the
leptogenesis. We consider the thermal and non-thermal leptogenesis based on the
right-handed neutrino decay in this model. A lower bound of the reheating
temperature required for the explanation of the baryon number asymmetry is
estimated as GeV for the thermal leptogenesis and GeV for
the non-thermal one.It can be lower than the upper bound of the reheating
temperature imposed by the cosmological gravitino problem. An example of the
construction of the discussed texture is also presented.Comment: 23 pages, 6 figure
Some Comments on Gravitational Entropy and the Inverse Mean Curvature Flow
The Geroch-Wald-Jang-Huisken-Ilmanen approach to the positive energy problem
to may be extended to give a negative lower bound for the mass of
asymptotically Anti-de-Sitter spacetimes containing horizons with exotic
topologies having ends or infinities of the form , in
terms of the cosmological constant. We also show how the method gives a lower
bound for for the mass of time-symmetric initial data sets for black holes with
vectors and scalars in terms of the mass, of the double extreme
black hole with the same charges. I also give a lower bound for the area of an
apparent horizon, and hence a lower bound for the entropy in terms of the same
function . This shows that the so-called attractor behaviour extends
beyond the static spherically symmetric case. and underscores the general
importance of the function . There are hints that higher dimensional
generalizations may involve the Yamabe conjectures.Comment: 13pp. late
Resonant Leptogenesis and Verifiable Seesaw from Large Extra Dimensions
In the presence of large extra dimensions, the fundamental scale could be as
low as a few TeV. This yields leptogenesis and seesaw at a TeV scale.
Phenomenologically two TeV-scale Majorana fermions with a small mass split can
realize a resonant leptogenesis whereas a TeV-scale Higgs triplet with a small
trilinear coupling to the standard model Higgs doublet can give a verifiable
seesaw. We propose an interesting scenario where the small parameters for the
resonant leptogenesis and the type-II seesaw can be simultaneously generated by
the propagation of lepton number violation from distant branes to our world.Comment: 5 pages. More discussions and references. Published in PR
Supersymmetric seesaw type II: CERN LHC and lepton flavour violating phenomenology
We study the supersymmetric version of the type-II seesaw mechanism assuming
minimal supergravity boundary conditions. We calculate branching ratios for
lepton flavour violating (LFV) scalar tau decays, potentially observable at the
LHC, as well as LFV decays at low energy, such as and
compare their sensitivity to the unknown seesaw parameters. In the minimal case
of only one triplet coupling to the standard model lepton doublets, ratios of
LFV branching ratios can be related unambigously to neutrino oscillation
parameters. We also discuss how measurements of soft SUSY breaking parameters
at the LHC can be used to indirectly extract information of the seesaw scale.Comment: 25 pages, 14 figures, references and appendix added, minor
corrections; final version published in Phys.Rev.
The impact of the 1783-1784 AD Laki eruption on global aerosol formation processes and cloud condensation nuclei
The 1783–1784 AD Laki flood lava eruption commenced on 8 June 1783 and released 122 Tg of sulphur dioxide gas over the course of 8 months into the upper troposphere and lower stratosphere above Iceland. Previous studies have examined the impact of the Laki eruption on sulphate aerosol and climate using general circulation models. Here, we study the impact on aerosol microphysical processes, including the nucleation of new particles and their growth to cloud condensation nuclei (CCN) using a comprehensive Global Model of Aerosol Processes (GLOMAP). Total particle concentrations in the free troposphere increase by a factor ~16 over large parts of the Northern Hemisphere in the 3 months following the onset of the eruption. Particle concentrations in the boundary layer increase by a factor 2 to 5 in regions as far away as North America, the Middle East and Asia due to long-range transport of nucleated particles. CCN concentrations (at 0.22% supersaturation) increase by a factor 65 in the upper troposphere with maximum changes in 3-month zonal mean concentrations of ~1400 cm<sup>−3</sup> at high northern latitudes. 3-month zonal mean CCN concentrations in the boundary layer at the latitude of the eruption increase by up to a factor 26, and averaged over the Northern Hemisphere, the eruption caused a factor 4 increase in CCN concentrations at low-level cloud altitude. The simulations show that the Laki eruption would have completely dominated as a source of CCN in the pre-industrial atmosphere. The model also suggests an impact of the eruption in the Southern Hemisphere, where CCN concentrations are increased by up to a factor 1.4 at 20&deg; S. Our model simulations suggest that the impact of an equivalent wintertime eruption on upper tropospheric CCN concentrations is only about one-third of that of a summertime eruption. The simulations show that the microphysical processes leading to the growth of particles to CCN sizes are fundamentally different after an eruption when compared to the unperturbed atmosphere, underlining the importance of using a fully coupled microphysics model when studying long-lasting, high-latitude eruptions
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