13,637 research outputs found
Rates of public health insurance coverage for children rise as rates of private coverage decline
This brief uses data from the 2008, 2009, and 2010 American Community Survey to document changes in rates of children’s health insurance, between private and public. The authors report that, nationally, private health insurance for children decreased by just under 2 percentage points, while public health insurance increased by nearly 3 percentage points. Rural places and central cities witnessed significant declines in rates of private health insurance for children in nearly every region. Rates of public insurance coverage rose in every region and place type. Children’s health insurance coverage overall continued to rise in 2010, increasing by 0.6 of a percentage point since 2009, and 1.9 percentage points since 2008
Financial frictions and the monetary transmission mechanism: theory, evidence and policy implications
This paper provides a brief survey of the role of financial frictions in the monetary transmission mechanism. After noting some of the key stylised facts that any model of the transmission mechanisms must be consistent with, we discuss both the classical interest rate channel and the credit and bank lending channels of monetary transmission. We then review the empirical evidence relating to the relative importance of these channels. Finally we consider what impact the presence of significant financial frictions might have on the conduct of monetary policy JEL Classification: E52, E58, E44bank-lending channel, credit channel, monetary policy, transmission mechanism
Prebiotic synthesis of nucleic acids
The origin of the first RNA polymers is central to most current theories regarding the origin of life. However, difficulties associated with the prebiotic formation of RNA have lead many researchers to conclude that simpler polymers, or proto-RNAs, preceded RNA. These earlier polymers would have been replaced by RNA over the course of evolution. A remaining difficulty for this theory is that the de novo synthesis of a feasible proto-RNA has not yet been demonstrated by plausible prebiotic reactions. This thesis focuses on two problems associated with prebiotic proto-RNA synthesis: The formation of nucleosides and the necessity of reversible backbone linkages for error correction in nucleic acid polymers.
"The Nucleoside Problem", or the lack of success in forming pyrimidine nucleosides by plausible prebiotic reactions, represents a significant stumbling block to the RNA world hypothesis. Nearly four decades ago Orgel and coworkers demonstrated that the purine nucleosides adenosine and inosine are synthesized by heating and drying their respective bases and ribose in the presence of magnesium, but these reaction conditions do not yield the pyrimidine nucleosides uridine or cytidine from their respective bases. In this thesis a potential solution to The Nucleoside Problem is hypothesized based upon a proposed chemical mechanism for nucleoside formation. This hypothesis is supported by the successful synthesis of 2-pyrimidinone nucleosides by a plausible prebiotic reaction in good yield, demonstrating that pyrimidine nucleosides could have been available in the prebiotic chemical inventory, but that uridine and cytidine were likely not abundant.
Reversible backbone linkages are necessary to provide a mechanism for error correction in non-enzymatic template-directed syntheses of proto-RNAs. In this thesis, acetals are explored as low-energy, reversible linkage groups for nucleosides in polymers. The synthesis of glyoxylate-acetal nucleic acids (gaNAs) through simple heating-drying reactions from neutral aqueous solutions is demonstrated, and these linkages are shown to be hydrolytically stable under a considerable range of solution conditions. Computational models demonstrate that the glyoxylate linkage is an excellent electronic and isosteric replacement for phosphate. Molecular dynamics simulations also indicate that a gaNA duplex would have structural properties that closely match a phosphate-linked RNA helix, suggesting the possibility for cross-pairing between gaNAs and RNAs, allowing for sequence transfer and genetic continuity through the evolution from proto-RNAs to RNA.
The principles illustrated in this thesis by 2-pyrimidinone nucleoside and gaNA synthesis can be extended to other prebiotic condensation reactions. Factors affecting condensation yield, such as thermodynamics, kinetics, reactant solubility, and salt effects, are summarized herein.Ph.D.Committee Chair: Hud, Nicholas V.; Committee Member: Fox, Ronald F.; Committee Member: Lynn, David G.; Committee Member: Powers, James C.; Committee Member: Wartell, Roger M.; Committee Member: Williams, Loren D
Letter from C. D. Bean to Representative Burdick Regarding Need for Barge to Ferry Trucks Across the Lake Created by the Garrison Dam, September 5, 1957
This letter, dated September 5, 1957, from Federal Supply Service Commissioner C. D. Bean to United States (US) Representative Usher Burdick responds to an inquiry related to transportation for the Three Affiliated Tribes across the Garrison Reservoir. The US Department of the Interior informed Bean\u27s office that the US Bureau of Indian Affairs does not have the authority to transfer ownership of property to the tribes. Bean recommends that the tribes purchase a surplus barge and jeeps as needed and encloses information about buying surplus property. The referenced enclosed booklet is not included with this document.
See also:
Letter from Representative Burdick to Clifton E. Mack Regarding Need for Barge to Ferry Trucks Across the Lake Created by the Garrison Dam, May 22, 1957https://commons.und.edu/burdick-papers/1350/thumbnail.jp
Reliability assessment of the 1964 mariner mars spacecraft
Numerical exercise of reliability model of Mariner Mars spacecraft and spacecraft subsystems reliabilit
Adiabatic instability in coupled dark energy-dark matter models
We consider theories in which there exists a nontrivial coupling between the
dark matter sector and the sector responsible for the acceleration of the
universe. Such theories can possess an adiabatic regime in which the
quintessence field always sits at the minimum of its effective potential, which
is set by the local dark matter density. We show that if the coupling strength
is much larger than gravitational, then the adiabatic regime is always subject
to an instability. The instability, which can also be thought of as a type of
Jeans instability, is characterized by a negative sound speed squared of an
effective coupled dark matter/dark energy fluid, and results in the exponential
growth of small scale modes. We discuss the role of the instability in specific
coupled CDM and Mass Varying Neutrino (MaVaN) models of dark energy, and
clarify for these theories the regimes in which the instability can be evaded
due to non-adiabaticity or weak coupling.Comment: 20 pages, 2 figures; final published versio
Perturbation Theory in k-Inflation Coupled to Matter
We consider k-inflation models where the action is a non-linear function of
both the inflaton and the inflaton kinetic term. We focus on a scalar-tensor
extension of k-inflation coupled to matter for which we derive a modified
Mukhanov-Sasaki equation for the curvature perturbation. Significant
corrections to the power spectrum appear when the coupling function changes
abruptly along the inflationary trajectory. This gives rise to a modification
of Starobinsky's model of perturbation features. We analyse the way the power
spectrum is altered in the infrared when such features are present.Comment: 20 pages, 1 figur
Labor Market Conditions and Post-Reform Declines in Welfare Receipt Among Immigrants
Considerable research attention has been devoted to the question of whether and to what extent
changes in welfare policy legislated in the 1990s might have deterred immigrant participation in
welfare programs, although only post-1996 immigrants were explicitly targeted by most of the
changes. Some analysts have argued that such so-called chilling effects have lowered
immigrant participation, and others have argued that this is true only in California. This paper
analyzes the role of local labor market conditions in explaining declines in the welfare
participation trends of immigrants and reductions in the nativity participation gap for the period
1994 to 1999. The data, extracted from the March Current Population Survey, indicate that
immigrants? participation in welfare declined more rapidly than natives? during the latter half of
the decade. Our results show that variation in the unemployment and employment rates across
MSAs and states explain the observed relative post-welfare reform decrease among immigrants,
with immigrant welfare utilization being sensitive to changes in both employment and
unemployment rates. The inclusion of state fixed effects in probability models suggests that the
relative decline among immigrants is not due to unobservable heterogeneity across states, but
rather to differences in local labor market conditions. The policy implications of the findings are
discussed
Delayed Recombination and Cosmic Parameters
Current cosmological constraints from Cosmic Microwave Background (CMB)
anisotropies are typically derived assuming a standard recombination scheme,
however additional resonance and ionizing radiation sources can delay
recombination, altering the cosmic ionization history and the cosmological
inferences drawn from CMB data. We show that for recent observations of CMB
anisotropy, from the Wilkinson Microwave Anisotropy Probe satellite mission
5-year survey (WMAP5) and from the ACBAR experiment, additional resonance
radiation is nearly degenerate with variations in the spectral index, n_s, and
has a marked effect on uncertainties in constraints on the Hubble constant, age
of the universe, curvature and the upper bound on the neutrino mass. When a
modified recombination scheme is considered, the redshift of recombination is
constrained to z_*=1078\pm11, with uncertainties in the measurement weaker by
one order of magnitude than those obtained under the assumption of standard
recombination while constraints on the shift parameter are shifted by 1-sigma
to R=1.734\pm0.028. Although delayed recombination limits the precision of
parameter estimation from the WMAP satellite, we demonstrate that this should
not be the case for future, smaller angular scales measurements, such as those
by the Planck satellite mission.Comment: 9 pages, 9 figure
Can the Universe escape eternal acceleration?
Recent astronomical observations of distant supernovae light-curves suggest
that the expansion of the universe has recently begun to accelerate.
Acceleration is created by an anti-gravitational repulsive stress, like that
produced by a positive cosmological constant, or universal vacuum energy. It
creates a rather bleak eschatological picture. An ever-expanding universe's
future appears to be increasingly dominated by its constant vacuum energy. A
universe doomed to accelerate forever will produce a state of growing
uniformity and cosmic loneliness. Structures participating in the cosmological
expansion will ultimately leave each others' horizons and
information-processing must eventually die out. Here, we examine whether this
picture is the only interpretation of the observations. We find that in many
well-motivated scenarios the observed spell of vacuum domination is only a
transient phenomenon. Soon after acceleration starts, the vacuum energy's
anti-gravitational properties are reversed, and a matter-dominated decelerating
cosmic expansion resumes. Thus, contrary to general expectations, once an
accelerating universe does not mean always an accelerating universe.Comment: 6 pages, 2 figure
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