26,140 research outputs found
Bias, redshift space distortions and primordial nongaussianity of nonlinear transformations: application to Lyman alpha forest
On large scales a nonlinear transformation of matter density field can be
viewed as a biased tracer of the density field itself. A nonlinear
transformation also modifies the redshift space distortions in the same limit,
giving rise to a velocity bias. In models with primordial nongaussianity a
nonlinear transformation generates a scale dependent bias on large scales. We
derive analytic expressions for these for a general nonlinear transformation.
These biases can be expressed entirely in terms of the one point distribution
function (PDF) of the final field and the parameters of the transformation. Our
analysis allows one to devise nonlinear transformations with nearly arbitrary
bias properties, which can be used to increase the signal in the large scale
clustering limit. We apply the results to the ionizing equilibrium model of
Lyman-alpha forest, in which Lyman-alpha flux F is related to the density
perturbation delta via a nonlinear transformation. Velocity bias can be
expressed as an average over the Lyman-alpha flux PDF. At z=2.4 we predict the
velocity bias of -0.1, compared to the observed value of -0.13 +/- 0.03. Bias
and primordial nongaussianity bias depend on the parameters of the
transformation. Measurements of bias can thus be used to constrain these
parameters, and for reasonable values of the ionizing background intensity we
can match the predictions to observations. Matching to the observed values we
predict the ratio of primordial nongaussianity bias to bias to have the
opposite sign and lower magnitude than the corresponding values for the highly
biased galaxies, but this depends on the model parameters and can also vanish
or change the sign.Comment: 18 pages, 1 figur
Gas low pressure low flow rate metering system Patent
Flowmeters for sensing low fluid flow rate and pressure for application to respiration rate studie
Efficient sorting of Bessel beams
We demonstrate the efficient sorter of Bessel beams separating both the azimuthal and radial components. This is based upon the recently reported transformation of angular to transverse momentum states. We separately identify over forty azimuthal and radial components, with a radial spacing of 1588 m<sup>−1</sup>, and outline how the device could be used to identify the two spatial dimensions simultaneously
Collide and Conquer: Constraints on Simplified Dark Matter Models using Mono-X Collider Searches
The use of simplified models as a tool for interpreting dark matter collider
searches has become increasingly prevalent, and while early Run II results are
beginning to appear, we look to see what further information can be extracted
from the Run I dataset. We consider three `standard' simplified models that
couple quarks to fermionic singlet dark matter: an -channel vector mediator
with vector or axial-vector couplings, and a -channel scalar mediator. Upper
limits on the couplings are calculated and compared across three alternate
channels, namely mono-jet, mono- (leptonic) and mono- (hadronic). The
strongest limits are observed in the mono-jet channel, however the
computational simplicity and absence of significant -channel model width
effects in the mono-boson channels make these a straightforward and competitive
alternative. We also include a comparison with relic density and direct
detection constraints.Comment: 32 pages, 8 figures; v2: minor changes, conclusion unchanged, matches
published versio
Corotating energetic particle and fast plasma streams in the inner and outer solar system: Radial dependence and energy spectra
Interplanetary acceleration processes are shown as the most plausible explanation for the observed corotating energetic particle events. The relation between the energetic particle events and the properties of the high speed solar wind streams observed at 1 AU were investigated along with the form of the energy spectrum of the corotating energetic particle streams and its variation with respect to CIR boundaries and with radial distance. It is shown that: (1) at 1 AU a correlation exists between the j particle intensity and the solar wind velocity measured during the rising part of the event, of the form I is proportional to exp (V sub sw/V sub o); and (2) the energy spectra from .5 to 20 MeV are well represented by an exponential in momentum of the form dJ/dP = C exp (-P/P sub o). This representation is found to apply from .45 AU to beyond 5 AU. The variation of P sub o with respect to the CIR boundaries was studied using a method of superposed epoch analysis. It is shown that at 1 AU the spectrum remains constant during the first two days and then progressively flattens; between 3-4AU
The radial variation of corotating energetic particle streams in the inner and outer solar system
The radial gradient of long-lived, corotating energetic particle streams was measured using observations of .9-2.2 MeV protons from Helios 1 and 2, IMP 7, Pioneer 10 and Pioneer 11. A positive gradient of approximately 350% per AU is found between .3 AU and 1 AU. Between 1 AU and some 3-5 AU, the gradient is variable with an average value of 100% per AU which is consistent with earlier statistical results. A comparison between measurements at 9 AU and approximately 4 AU shows a negative gradient which is variable from -40 to -100% per AU. Possible solar latitudinal effects on these gradient studies are also discussed. Using solar wind and magnetic field data from Helios 1 between 1 AU and .3 AU, the relation between corotating energetic particle events in the inner solar system and the interplanetary medium is examined. It is found that the energetic particles are contained inside the high speed solar wind stream in a region adjacent to the interaction region between low speed and high speed streams
New Q-ball Solutions in Gauge-Mediation, Affleck-Dine Baryogenesis and Gravitino Dark Matter
Affleck-Dine (AD) baryogenesis along a d=6 flat direction in gauge-mediated
supersymmetry-breaking (GMSB) models can produce unstable Q-balls which
naturally have field strength similar to the messenger scale. In this case a
new kind of Q-ball is formed, intermediate between gravity-mediated and
gauge-mediated type. We study in detail these new Q-ball solutions, showing how
their properties interpolate between standard gravity-mediated and
gauge-mediated Q-balls as the AD field becomes larger than the messenger scale.
It is shown that E/Q for the Q-balls can be greater than the nucleon mass but
less than the MSSM-LSP mass, leading to Q-ball decay directly to Standard Model
fermions with no MSSM-LSP production. More significantly, if E/Q is greater
than the MSSM-LSP mass, decaying Q-balls can provide a natural source of
non-thermal MSSM-LSPs, which can subsequently decay to gravitino dark matter
without violating nucleosynthesis constraints. The model therefore provides a
minimal scenario for baryogenesis and gravitino dark matter in the
gauge-mediated MSSM, requiring no new fields.Comment: 13 pages, 9 figures. Some corrections and additional discussion.
Version published in JCA
The Influence of Formulation, Buffering, pH and Divalent Cations on the Activity of Endothall on Hydrilla.
Endothall has been used as an aquatic herbicide for more
than 40 years and provides very effective weed control of
many weeds. Early research regarding the mechanism-of-action
of endothall contradicts the symptomology normally associated
with the product. Recent studies suggest endothall
is a respiratory toxin but the mechanism-of-action remains
unknown. To further elucidate the activity of endothall, several
endothall formulations were evaluated for their effects
on ion leakage, oxygen consumption and photosynthetic oxygen
evolution from hydrilla shoot tips. The influence of pH,
buffering and divalent cations was also evaluated. (PDF contains 6 pages.
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