28 research outputs found
An absolute calibration system for millimeter-accuracy APOLLO measurements
Lunar laser ranging provides a number of leading experimental tests of
gravitation -- important in our quest to unify General Relativity and the
Standard Model of physics. The Apache Point Observatory Lunar Laser-ranging
Operation (APOLLO) has for years achieved median range precision at the ~2 mm
level. Yet residuals in model-measurement comparisons are an order-of-magnitude
larger, raising the question of whether the ranging data are not nearly as
accurate as they are precise, or if the models are incomplete or
ill-conditioned. This paper describes a new absolute calibration system (ACS)
intended both as a tool for exposing and eliminating sources of systematic
error, and also as a means to directly calibrate ranging data in-situ. The
system consists of a high-repetition-rate (80 MHz) laser emitting short (< 10
ps) pulses that are locked to a cesium clock. In essence, the ACS delivers
photons to the APOLLO detector at exquisitely well-defined time intervals as a
"truth" input against which APOLLO's timing performance may be judged and
corrected. Preliminary analysis indicates no inaccuracies in APOLLO data beyond
the ~3 mm level, suggesting that historical APOLLO data are of high quality and
motivating continued work on model capabilities. The ACS provides the means to
deliver APOLLO data both accurate and precise below the 2 mm level.Comment: 21 pages, 10 figures, submitted to Classical and Quantum Gravit
Equitable representation in councils: theory and an application to the United Nations Security Council
We analyze democratic equity in council voting games (CVGs). In a CVG, a
voting body containing all members delegates decision-making to a (time-varying) subset
of its members, as describes, e.g., the relationship between the United Nations General
Assembly and the United Nations Security Council (UNSC). We develop a theoretical
framework for analyzing democratic equitability in CVGs at both the country and region
levels, and for different assumptions regarding preference correlation. We apply the
framework to evaluate the equitability of the UNSC, and the claims of those who seek to
reform it. We find that the individual permanent members are overrepresented by between
21.3 times (United Kingdom) and 3.8 times (China) from a country-level perspective,
while from a region perspective Eastern Europe is the most heavily overrepresented region
with more than twice its equitable representation, and Africa the most heavily underrepresented.
Our equity measures do not preclude some UNSC members from exercising veto
rights, however
Granularity of Services – an Economic Analysis
Service-oriented architectures are widely discussed as a design principle for application and enterprise architectures. Nevertheless, an adequate granularity of services has not yet been researched sufficiently from an economic perspective. The finer the granularity to realize the functions of a process, the higher the number of services is, and the more effort has to be directed towards composing them. In contrast, very coarse grained services bear the disadvantages of higher implementation costs and lower reuse potential (e.g., in different processes). The aim of the decision model proposed in this paper is to determine an adequate granularity of services from an economical perspective. Thus, degrees of freedom, which often exist for the choice of granularity after a domain analysis, can be leveraged to realize a cost-efficient solution. We illustrate the applicability and practical benefits of the decision model with an example from the context of a financial services provider