2,186 research outputs found
Panel 4: The Next Frontier: Space and Beyond
What does an international law of property portend for future extraterrestrial ambitions, such as moon and near asteroid mining? How does the Outer Space Treaty address the global commons of outer space? The law of outer space is “both unclear and incomplete” – what are the implications of an international law of property for the development of outer space law
The Damping Tail of CMB Anisotropies
By decomposing the damping tail of CMB anisotropies into a series of transfer
functions representing individual physical effects, we provide ingredients that
will aid in the reconstruction of the cosmological model from small-scale CMB
anisotropy data. We accurately calibrate the model-independent effects of
diffusion and reionization damping which provide potentially the most robust
information on the background cosmology. Removing these effects, we uncover
model-dependent processes such as the acoustic peak modulation and
gravitational enhancement that can help distinguish between alternate models of
structure formation and provide windows into the evolution of fluctuations at
various stages in their growth.Comment: 24pgs, aaspp4, 10 figs. included; supporting material (e.g. color
figures) at http://www.sns.ias.edu/~whu/pub.htm
Single-Tube Real-Time PCR Assay for Differentiation of Ixodes Affinis and Ixodes scapularis
Ixodes affinis Neumann (1899) and Ixodes scapularis Say (1821) are tick vectors of the etiologic agent of Lyme disease, Borrelia burgdorferi sensu stricto. Ixodes affinis and I. scapularis are morphologically very similar, and as they are sympatric in the mid- and south-Atlantic U.S. coastal states, their accurate identification is crucial to studies of disease and vector ecology in this area. This work describes a rapid, single-tube SYBR® Green-based real-time PCR assay for differentiation of I. affinis and I. scapularis at all life stages. The assay employs 2 pairs of species specific primers directed against the internal transcribed spacer 2 (ITS2) region of the nuclear rRNA operon. Amplification products for these primer pairs differ in size and may be differentiated with a melt curve analysis. This tool is intended as a supplement to morphological methods for accurate identification of these ticks
Observationally Determining the Properties of Dark Matter
Determining the properties of the dark components of the universe remains one
of the outstanding challenges in cosmology. We explore how upcoming CMB
anisotropy measurements, galaxy power spectrum data, and supernova (SN)
distance measurements can observationally constrain their gravitational
properties with minimal assumptions on the theoretical side. SN observations
currently suggest the existence of dark matter with an exotic equation of state
p/rho < -1/3 that accelerates the expansion of the universe. When combined with
CMB anisotropy measurements, SN or galaxy survey data can in principle
determine the equation of state and density of this component separately,
regardless of their value, as long as the universe is spatially flat. Combining
these pairs creates a sharp consistency check. If p/rho > -1/2, then the
clustering behavior (sound speed) of the dark component can be determined so as
to test the scalar-field ``quintessence'' hypothesis. If the exotic matter
turns out instead to be simply a cosmological constant (p/rho = -1), the
combination of CMB and galaxy survey data should provide a significant
detection of the remaining dark matter, the neutrino background radiation
(NBR). The gross effect of its density or temperature on the expansion rate is
ill-constrained as it is can be mimicked by a change in the matter density.
However, anisotropies of the NBR break this degeneracy and should be detectable
by upcoming experiments.Comment: 16 pages, 10 figures, RevTeX, submitted to PR
The Vehicle, February 1960, Vol. 2 no. 1
Vol. 2, No. 1
Table of Contents
Editorialpage 2
A White Man\u27s BurdenRobert Mills Frenchpage 4
Passing TrainWayne Bakerpage 8
AutumnMajor Dan Ragainpage 8
Chaos in CulturevilleJ.B. Youngpage 9
Cure-allJerry N. Whitepage 13
Love-Long DistanceMary Ellen Mockbeepage 13
Metropolitan CaravanThomas McPeakpage 14
Ode to the Lion HuntersRichard Blairpage 16
ImmortalityM.E.M.page 16
EntranceSam Martinpage 16https://thekeep.eiu.edu/vehicle/1006/thumbnail.jp
The Vehicle, February 1960, Vol. 2 no. 1
Vol. 2, No. 1
Table of Contents
Editorialpage 2
A White Man\u27s BurdenRobert Mills Frenchpage 4
Passing TrainWayne Bakerpage 8
AutumnMajor Dan Ragainpage 8
Chaos in CulturevilleJ.B. Youngpage 9
Cure-allJerry N. Whitepage 13
Love-Long DistanceMary Ellen Mockbeepage 13
Metropolitan CaravanThomas McPeakpage 14
Ode to the Lion HuntersRichard Blairpage 16
ImmortalityM.E.M.page 16
EntranceSam Martinpage 16https://thekeep.eiu.edu/vehicle/1006/thumbnail.jp
Weak Lensing of the CMB: A Harmonic Approach
Weak lensing of CMB anisotropies and polarization for the power spectra and
higher order statistics can be handled directly in harmonic-space without
recourse to real-space correlation functions. For the power spectra, this
approach not only simplifies the calculations but is also readily generalized
from the usual flat-sky approximation to the exact all-sky form by replacing
Fourier harmonics with spherical harmonics. Counterintuitively, due to the
nonlinear nature of the effect, errors in the flat-sky approximation do not
improve on smaller scales. They remain at the 10% level through the acoustic
regime and are sufficiently large to merit adoption of the all-sky formalism.
For the bispectra, a cosmic variance limited detection of the correlation with
secondary anisotropies has an order of magnitude greater signal-to-noise for
combinations involving magnetic parity polarization than those involving the
temperature alone. Detection of these bispectra will however be severely noise
and foreground limited even with the Planck satellite, leaving room for
improvement with higher sensitivity experiments. We also provide a general
study of the correspondence between flat and all sky potentials, deflection
angles, convergence and shear for the power spectra and bispectra.Comment: 17 pages, 5 figures, submitted to PR
The Angular Trispectra of CMB Temperature and Polarization
We develop the formalism necessary to study four-point functions of the
cosmic microwave background (CMB) temperature and polarization fields. We
determine the general form of CMB trispectra, with the constraints imposed by
the assumption of statistical isotropy of the CMB fields, and derive
expressions for their estimators, as well as their Gaussian noise properties.
We apply these techniques to initial non-Gaussianity of a form motivated by
inflationary models. Due to the large number of four-point configurations, the
sensitivity of the trispectra to initial non-Gaussianity approaches that of the
temperature bispectrum at high multipole moment. These trispectra techniques
will also be useful in the study of secondary anisotropies induced for example
by the gravitational lensing of the CMB by the large scale structure of the
universe.Comment: 16 pages, 4 figures; typographical errors correcte
CMB Anisotropies: Total Angular Momentum Method
A total angular momentum representation simplifies the radiation transport
problem for temperature and polarization anisotropy in the CMB. Scattering
terms couple only the quadrupole moments of the distributions and each moment
corresponds directly to the observable angular pattern on the sky. We develop
and employ these techniques to study the general properties of anisotropy
generation from scalar, vector and tensor perturbations to the metric and the
matter, both in the cosmological fluids and from any seed perturbations (e.g.
defects) that may be present. The simpler, more transparent form and derivation
of the Boltzmann equations brings out the geometric and model-independent
aspects of temperature and polarization anisotropy formation. Large angle
scalar polarization provides a robust means to distinguish between isocurvature
and adiabatic models for structure formation in principle. Vector modes have
the unique property that the CMB polarization is dominated by magnetic type
parity at small angles (a factor of 6 in power compared with 0 for the scalars
and 8/13 for the tensors) and hence potentially distinguishable independent of
the model for the seed. The tensor modes produce a different sign from the
scalars and vectors for the temperature-polarization correlations at large
angles. We explore conditions under which one perturbation type may dominate
over the others including a detailed treatment of the photon-baryon fluid
before recombination.Comment: 32 pg., 10 figs., RevTeX, minor changes reflect published version,
minor typos corrected, also available at http://www.sns.ias.edu/~wh
Cosmological Limits on the Neutrino Mass from the Lya Forest
The Lya forest in quasar spectra probes scales where massive neutrinos can
strongly suppress the growth of mass fluctuations. Using hydrodynamic
simulations with massive neutrinos, we successfully test techniques developed
to measure the mass power spectrum from the forest. A recent observational
measurement in conjunction with a conservative implementation of other
cosmological constraints places upper limits on the neutrino mass: m_nu < 5.5
eV for all values of Omega_m, and m_nu < 2.4 (Omega_m/0.17 -1) eV, if 0.2 <
Omega_m <0.5 as currently observationally favored (both 95 % C.L.).Comment: 4 pages, 2 ps figures, REVTex, submitted to Phys. Rev. Let
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