52,887 research outputs found
Neutrino Physics (theory)
Nonzero neutrino masses are the first definitive need to extend the standard
model. After reviewing the basic framework, I describe the status of some of
the major issues, including tests of the basic framework of neutrino masses and
mixings; the question of Majorana vs. Dirac; the spectrum, mixings, and number
of neutrinos; models, with special emphasis on constraints from typical
superstring constructions (which are not consistent with popular bottom-up
assumptions); and other implications.Comment: 13 pages, 6 figures, invited plenary talk at ICHEP200
The role of economics in the QUERI program: QUERI Series.
Background: The United States (U.S.) Department of Veterans Affairs (VA) Quality Enhancement Research Initiative (QUERI) has implemented economic analyses in single-site and multi-site clinical trials. To date, no one has reviewed whether the QUERI Centers are taking an optimal approach to doing so. Consistent with the continuous learning culture of the QUERI Program, this paper provides such a reflection. Methods: We present a case study of QUERI as an example of how economic considerations can and should be integrated into implementation research within both single and multi-site studies. We review theoretical and applied cost research in implementation studies outside and within VA. We also present a critique of the use of economic research within the QUERI program. Results: Economic evaluation is a key element of implementation research. QUERI has contributed many developments in the field of implementation but has only recently begun multisite implementation trials across multiple regions within the national VA healthcare system. These trials are unusual in their emphasis on developing detailed costs of implementation, as well as in the use of business case analyses (budget impact analyses). Conclusion: Economics appears to play an important role in QUERI implementation studies, only after implementation has reached the stage of multi-site trials. Economic analysis could better inform the choice of which clinical best practices to implement and the choice of implementation interventions to employ. QUERI economics also would benefit from research on costing methods and development of widely accepted international standards for implementation economics.implementation science; cost analysis; cost-effectiveness; health care cost; health systems;
Dark Energy, Inflation and Extra Dimensions
We consider how accelerated expansion, whether due to inflation or dark
energy, imposes strong constraints on fundamental theories obtained by
compactification from higher dimensions. For theories that obey the null energy
condition (NEC), we find that inflationary cosmology is impossible for a wide
range of compactifications; and a dark energy phase consistent with
observations is only possible if both Newton's gravitational constant and the
dark energy equation-of-state vary with time. If the theory violates the NEC,
inflation and dark energy are only possible if the NEC-violating elements are
inhomogeneously distributed in thecompact dimensions and vary with time in
precise synchrony with the matter and energy density in the non-compact
dimensions. Although our proofs are derived assuming general relativity applies
in both four and higher dimensions and certain forms of metrics, we argue that
similar constraints must apply for more general compactifications.Comment: 26 pages, 1 figure. v2: reference added, typos correcte
Orthorhombic Phase of Crystalline Polyethylene: A Monte Carlo Study
In this paper we present a classical Monte Carlo simulation of the
orthorhombic phase of crystalline polyethylene, using an explicit atom force
field with unconstrained bond lengths and angles and periodic boundary
conditions. We used a recently developed algorithm which apart from standard
Metropolis local moves employs also global moves consisting of displacements of
the center of mass of the whole chains in all three spatial directions as well
as rotations of the chains around an axis parallel to the crystallographic
c-direction. Our simulations are performed in the NpT ensemble, at zero
pressure, and extend over the whole range of temperatures in which the
orthorhombic phase is experimentally known to be stable (10 - 450 K). In order
to investigate the finite-size effects in this extremely anisotropic crystal,
we used different system sizes and different chain lengths, ranging from C_12
to C_96 chains, the total number of atoms in the super-cell being between 432
and 3456. We show here the results for structural parameters, such as the
orthorhombic cell parameters a,b,c, and the setting angle of the chains, as
well as internal parameters of the chains, such as the bond lengths and angles.
Among thermodynamic quantities, we present results for thermal expansion
coefficients, elastic constants and specific heat. We discuss the temperature
dependence of the measured quantities as well as the related finite-size
effects. In case of lattice parameters and thermal expansion coefficients, we
compare our results to those obtained from other theoretical approaches as well
as to some available experimental data. We also suggest some possible ways of
extending this study.Comment: 27 pages, RevTex, 24 figures, submitted to Journal of Chemical
Physic
Dungeness crab research program
In 1974, the California State Legislature, recognizing the
problem of low yields from the Dungeness crab resource of
central California, directed the Department of Fish and Game
to conduct an investigation into the causes of the decline.
The Operations Research Branch of the Department has conducted
preliminary studies and field operations necessary to formulate the Dungeness Crab Research Program. The objectives,
research design, and work plans are presented for a 4-year
program from July 1, 1975 through August 31, 1979. (38pp.
Switching and Extension of a [c2]Daisy-Chain Dimer Polymer
We report the synthesis of a [c2]daisy-chain dimer via ruthenium-catalyzed ring-closing olefin metathesis. Confirmation of the interlocked nature of the structure was achieved through single-crystal X-ray diffraction analysis. The dimer could be readily switched from the bound to the unbound conformation by treatment with 3.0 equiv of KOH and subsequently reprotonated by treatment with 3.0 equiv of HPF_6. Azide functionalization of the dimer enabled incorporation in linear step-growth polymer chains using the alkyne-azide âclickâ reaction. Gel permeation chromatography coupled with multiangle laser light scattering analysis showed the polymers contained 22 dimers and had a radius of gyration of 14.8 nm. Acylation of the amines of the dimers sterically forced elongation of the interlocked units, and MALLS analysis of the polymer showed a 48% increase in the R_g (21.4 nm)
Nonperturbative ``Lattice Perturbation Theory''
We discuss a program for replacing standard perturbative methods with Monte
Carlo simulations in short distance lattice gauge theory calculations.Comment: 3 pages, uuencoded Latex file, two embedded figures and .sty file
include
Improvement of oral reports through the students' use of audio-visual aids
Author misnumbered thesis. Please note that there are TWO page 108s, but the continuity is the same. Thesis (Ed.M.)--Boston Universit
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