14,261 research outputs found
To Reform Medicare, Reform Incentives and Organization
Alain C. Enthoven's paper, To Reform Medicare, Reform Incentives And Organization, explains how the principles of cost-responsible consumer choice among competing health-insurance plans, sometimes called "managed competition," can both improve quality and reduce cost in the federal government's Medicare program
Molecular propensity as a driver for explorative reactivity studies
Quantum chemical studies of reactivity involve calculations on a large number
of molecular structures and comparison of their energies. Already the set-up of
these calculations limits the scope of the results that one will obtain,
because several system-specific variables such as the charge and spin need to
be set prior to the calculation. For a reliable exploration of reaction
mechanisms, a considerable number of calculations with varying global
parameters must be taken into account, or important facts about the reactivity
of the system under consideration can go undetected. For example, one could
miss crossings of potential energy surfaces for different spin states or might
not note that a molecule is prone to oxidation. Here, we introduce the concept
of molecular propensity to account for the predisposition of a molecular system
to react across different electronic states in certain nuclear configurations.
Within our real-time quantum chemistry framework, we developed an algorithm
that allows us to be alerted to such a propensity of a system under
consideration.Comment: 10 pages, 7 figure
Realization of a Laser Cooled Microwave Power Standard (conference digest)
We demonstrate the feasibility of a novel microwave power standard based on
the electromagnetic interaction with cold atoms. Under the effect of the
radiation, the internal state populations will undergo a Rabi oscillation. The
measurement of its frequency will allow the determination of the
electromagnetic field strength.Comment: 2 pages, 1 figur
Exploration of Reaction Pathways and Chemical Transformation Networks
For the investigation of chemical reaction networks, the identification of
all relevant intermediates and elementary reactions is mandatory. Many
algorithmic approaches exist that perform explorations efficiently and
automatedly. These approaches differ in their application range, the level of
completeness of the exploration, as well as the amount of heuristics and human
intervention required. Here, we describe and compare the different approaches
based on these criteria. Future directions leveraging the strengths of chemical
heuristics, human interaction, and physical rigor are discussed.Comment: 48 pages, 4 figure
Accuracy of an Atomic Microwave Power Standard
We have built an atomic microwave power standard based on the electromagnetic
interaction with laser-cooled atoms. The atoms traversed a waveguide
transmission line, and under the effect of the radiation, the internal state
populations underwent a Rabi flopping oscillation. Measurement of the
oscillation frequency allowed the determination of the incident microwave
power. As many of 60 oscillations were observed over a dynamic range of 20 dB
and the standard deviation of the measurements was about 0.02%. The measured
frequency was compared to a calculated one and an agreement of 1.3% with an
uncertainty of 5% (rectangular) was found.Comment: 5 figure
Large restricted sumsets in general abelian group
Let A, B and S be three subsets of a finite Abelian group G. The restricted
sumset of A and B with respect to S is defined as A\wedge^{S} B= {a+b: a in A,
b in B and a-b not in S}. Let L_S=max_{z in G}| {(x,y): x,y in G, x+y=z and x-y
in S}|. A simple application of the pigeonhole principle shows that
|A|+|B|>|G|+L_S implies A\wedge^S B=G. We then prove that if |A|+|B|=|G|+L_S
then |A\wedge^S B|>= |G|-2|S|. We also characterize the triples of sets (A,B,S)
such that |A|+|B|=|G|+L_S and |A\wedge^S B|= |G|-2|S|. Moreover, in this case,
we also provide the structure of the set G\setminus (A\wedge^S B).Comment: Paper submitted November 15, 2011. To appear European Journal of
Combinatorics, special issue in memorian Yahya ould Hamidoune (2013
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