6,472 research outputs found
Systematic Mischaracterization of Exoplanetary System Dynamical Histories from a Model Degeneracy near Mean-motion Resonance
There is a degeneracy in the radial velocity exoplanet signal between a single planet on an eccentric orbit and a two-planet system with a period ratio of 2:1. This degeneracy could lead to misunderstandings of the dynamical histories of planetary systems as well as measurements of planetary abundances if the correct architecture is not established. We constrain the rate of mischaracterization by analysing a sample of 60 non-transiting, radial velocity systems orbiting main-sequence stars from the NASA Exoplanet Archive (NASA Archive) using a new Bayesian model comparison pipeline. We find that 15 systems (25 per cent of our sample) show compelling evidence for the two-planet case with a confidence level of 95 per cent
STOCHASTIC TECHNOLOGY, RISK PREFERENCES, AND THE USE OF POLLUTING INPUTS
We investigate the comparative static effects of environmental and agricultural policies on pesticide and fertilizer use. Since such effects depend on technology and risk preference parameters, we estimate these from a panel data set of Illinois farms. Generalized method of moments is used on a set of nonlinear first order conditions.Environmental Economics and Policy,
Neogene grabens in southernmost Illinois
National Earthquake Hazards Reduction Program Award No. 1434-HQ-97-GR-03195Ope
Neogene grabens in southernmost Illinois
U.S. Geological Survey, Department of the Interior, National Earthquake Hazards Reduction Program Award No. 1434-HQ-97-GR-03195Ope
The Strength of One-Piece Solid, Build-Up and Laminated Wood Airplane Wing Beams
The purpose of this report is to summarize the results of all wood airplane wing beams tested to date in the Bureau of Standards Laboratory in order that the various kinds of wood and methods of construction may be compared. All beams tested were of an I section and the majority were somewhat similar in size and cross section to the front wing beam of the Curtiss JN-4 machine. Construction methods may be classed as (1) solid beams cut from solid stock; (2) three-piece beams, built up of three pieces, web and flanges glued together by a tongue-and-groove joint and (3) laminated beams built up of thin laminations of wood glued together
Elementary simulation of tethered Brownian motion
We describe a simple numerical simulation, suitable for an undergraduate
project (or graduate problem set), of the Brownian motion of a particle in a
Hooke-law potential well. Understanding this physical situation is a practical
necessity in many experimental contexts, for instance in single molecule
biophysics; and its simulation helps the student to appreciate the dynamical
character of thermal equilibrium. We show that the simulation succeeds in
capturing behavior seen in experimental data on tethered particle motion.Comment: Submitted to American Journal of Physic
Precinct straddling of city boundaries
Journal ArticleSuppose a situation in which citizens of a particular city vote in county, state and national elections, but in which their combined vote for each candidate is not clearly separable from the votes of residents of adjacent areas outside of the city. It can be argued that the inability to identify the city vote would have undesirable implications for the visibility of the political preferences of the people of the city, for the reliability and indeed validity of the process of administering city elections and for the accessibility of the city to analysis of its political history
Chemical mechanical polishing of thin film diamond
The demonstration that Nanocrystalline Diamond (NCD) can retain the superior
Young's modulus (1,100 GPa) of single crystal diamond twinned with its ability
to be grown at low temperatures (<450 {\deg}C) has driven a revival into the
growth and applications of NCD thin films. However, owing to the competitive
growth of crystals the resulting film has a roughness that evolves with film
thickness, preventing NCD films from reaching their full potential in devices
where a smooth film is required. To reduce this roughness, films have been
polished using Chemical Mechanical Polishing (CMP). A Logitech Tribo CMP tool
equipped with a polyurethane/polyester polishing cloth and an alkaline
colloidal silica polishing fluid has been used to polish NCD films. The
resulting films have been characterised with Atomic Force Microscopy, Scanning
Electron Microscopy and X-ray Photoelectron Spectroscopy. Root mean square
roughness values have been reduced from 18.3 nm to 1.7 nm over 25 {\mu}m,
with roughness values as low as 0.42 nm over ~ 0.25 {\mu}m. A polishing
mechanism of wet oxidation of the surface, attachment of silica particles and
subsequent shearing away of carbon has also been proposed.Comment: 6 pages, 6 figure
Event-Driven Network Programming
Software-defined networking (SDN) programs must simultaneously describe
static forwarding behavior and dynamic updates in response to events.
Event-driven updates are critical to get right, but difficult to implement
correctly due to the high degree of concurrency in networks. Existing SDN
platforms offer weak guarantees that can break application invariants, leading
to problems such as dropped packets, degraded performance, security violations,
etc. This paper introduces EVENT-DRIVEN CONSISTENT UPDATES that are guaranteed
to preserve well-defined behaviors when transitioning between configurations in
response to events. We propose NETWORK EVENT STRUCTURES (NESs) to model
constraints on updates, such as which events can be enabled simultaneously and
causal dependencies between events. We define an extension of the NetKAT
language with mutable state, give semantics to stateful programs using NESs,
and discuss provably-correct strategies for implementing NESs in SDNs. Finally,
we evaluate our approach empirically, demonstrating that it gives well-defined
consistency guarantees while avoiding expensive synchronization and packet
buffering
The visual binary AG Tri in Pictoris Association: can a debris disc cause very different rotation periods of its components?
We measure the photometric rotation periods of the components of multiple
systems in young stellar associations to investigate the causes of the observed
rotation period dispersion. We present the case of the wide binary AG Tri in
the 23-Myr young beta Pictoris Association consisting of K4 + M1 dwarfs. Our
multi-band, multi-season photometric monitoring allowed us to measure the
rotation periods of both components P_A = 12.4d and P_B = 4.66d, to detect a
prominent magnetic activity in the photosphere, likely responsible for the
measured radial velocity variations, and for the first time, a flare event on
the M1 component AG Tri B. We investigate either the possibility that the
faster rotating component may have suffered an enhanced primordial disc
dispersal, starting its PMS spin-up earlier than the slower rotating component,
or the possibility that the formation of a debris disc may have prevented AG
Tri A from gaining part of the angular momentum from the accreting disc.Comment: 28 pages, 7 figures, accepted for publication in Astrophysics and
Space Science 2015, (ASTR-D-15-00445R2
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