1,124 research outputs found
Online Timing Slack Measurement and its Application in Field-Programmable Gate Arrays
Reliability, power consumption and timing performance are key concerns for today's integrated circuits. Measurement techniques capable of quantifying the timing characteristics of a circuit, while it is operating, facilitate a range of benefits. Delay variation due to environmental and operational conditions, and degradation can be monitored by tracking changes in timing performance. Using the measurements in a closed-loop to control power supply voltage or clock frequency allows for the reduction of timing safety margins, leading to improvements in power consumption or throughput performance through the exploitation of better-than worst-case operation.
This thesis describes a novel online timing slack measurement method which can directly measure the timing performance of a circuit, accurately and with minimal overhead. Enhancements allow for the improvement of absolute accuracy and resolution. A compilation flow is reported that can automatically instrument arbitrary circuits on FPGAs with the measurement circuitry. On its own this measurement method is able to track the "health" of an integrated circuit, from commissioning through its lifetime, warning of impending failure or instigating pre-emptive degradation mitigation techniques.
The use of the measurement method in a closed-loop dynamic voltage and frequency scaling scheme has been demonstrated, achieving significant improvements in power consumption and throughput performance.Open Acces
Dodd-Frank Is a Pigouvian Regulation
Almost eight years after the passage of Dodd-Frank, financial institutions remain large, complex, and interconnected. Academics and policymakers across the ideological spectrum largely agree that Dodd-Frank has imposed substantial compliance costs on systematically important financial institutions (SIFis) without solving the problem that they are too big to fail. This Note argues that Dodd-Frank\u27s compliance costs have actually served an important regulatory purpose. By analyzing the spinoffs and divestitures that have occurred at eleven SIFis since Dodd-Frank went into effect in 2010, this Note documents the extent to which the Act\u27s compliance costs have led SIFis to shed business lines of their own accord
A Study of the Shortest-Period Planets Found With Kepler
We present the results of a survey aimed at discovering and studying
transiting planets with orbital periods shorter than one day
(ultra--short-period, or USP, planets), using data from the {\em Kepler}
spacecraft. We computed Fourier transforms of the photometric time series for
all 200,000 target stars, and detected transit signals based on the presence of
regularly spaced sharp peaks in the Fourier spectrum. We present a list of 106
USP candidates, of which 18 have not previously been described in the
literature. In addition, among the objects we studied, there are 26 USP
candidates that had been previously reported in the literature which do not
pass our various tests. All 106 of our candidates have passed several standard
tests to rule out false positives due to eclipsing stellar systems. A low false
positive rate is also implied by the relatively high fraction of candidates for
which more than one transiting planet signal was detected. By assuming these
multi-transit candidates represent coplanar multi-planet systems, we are able
to infer that the USP planets are typically accompanied by other planets with
periods in the range 1-50 days, in contrast with hot Jupiters which very rarely
have companions in that same period range. Another clear pattern is that almost
all USP planets are smaller than 2 , possibly because gas giants in
very tight orbits would lose their atmospheres by photoevaporation when subject
to extremely strong stellar irradiation. Based on our survey statistics, USP
planets exist around approximately of G-dwarf stars, and
of K-dwarf stars.Comment: 20 pages, 10 figures. Submitted to ApJ. This version has been
reviewed by a refere
Transits and Occultations of an Earth-Sized Planet in an 8.5-Hour Orbit
We report the discovery of an Earth-sized planet () in
an 8.5-hour orbit around a late G-type star (KIC 8435766, Kepler-78). The
object was identified in a search for short-period planets in the {\it Kepler}
database and confirmed to be a transiting planet (as opposed to an eclipsing
stellar system) through the absence of ellipsoidal light variations or
substantial radial-velocity variations. The unusually short orbital period and
the relative brightness of the host star ( = 11.5) enable robust
detections of the changing illumination of the visible hemisphere of the
planet, as well as the occultations of the planet by the star. We interpret
these signals as representing a combination of reflected and reprocessed light,
with the highest planet dayside temperature in the range of 2300 K to 3100 K.
Follow-up spectroscopy combined with finer sampling photometric observations
will further pin down the system parameters and may even yield the mass of the
planet.Comment: Accepted for publication, ApJ, 10 pages and 6 figure
The gut microbiome defines social group membership in honey bee colonies
In the honey bee, genetically related colony members innately develop colony-specific cuticular hydrocarbon profiles, which serve as pheromonal nestmate recognition cues. Yet, despite high intracolony relatedness, the innate development of colony-specific chemical signatures by individual colony members is largely determined by the colony environment, rather than solely relying on genetic variants shared by nestmates. Therefore, it is puzzling how a nongenic factor could drive the innate development of a quantitative trait that is shared by members of the same colony. Here, we provide one solution to this conundrum by showing that nestmate recognition cues in honey bees are defined, at least in part, by shared characteristics of the gut microbiome across individual colony members. These results illustrate the importance of host-microbiome interactions as a source of variation in animal behavioral traits
Transiting Exoplanet Survey Satellite (TESS)
The Transiting Exoplanet Survey Satellite (TESS ) will search for planets transiting bright and nearby stars. TESS has been selected by NASA for launch in 2017 as an Astrophysics Explorer mission. The spacecraft will be placed into a highly elliptical 13.7-day orbit around the Earth. During its two-year mission, TESS will employ four wide-field optical CCD cameras to monitor at least 200,000 main-sequence dwarf stars with I[subscript C] (approximately less than) 13 for temporary drops in brightness caused by planetary transits. Each star will be observed for an interval ranging from one month to one year, depending mainly on the star's ecliptic latitude. The longest observing intervals will be for stars near the ecliptic poles, which are the optimal locations for follow-up observations with the James Webb Space Telescope. Brightness measurements of preselected target stars will be recorded every 2 min, and full frame images will be recorded every 30 min. TESS stars will be 10-100 times brighter than those surveyed by the pioneering Kepler mission. This will make TESS planets easier to characterize with follow-up observations. TESS is expected to find more than a thousand planets smaller than Neptune, including dozens that are comparable in size to the Earth. Public data releases will occur every four months, inviting immediate community-wide efforts to study the new planets. The TESS legacy will be a catalog of the nearest and brightest stars hosting transiting planets, which will endure as highly favorable targets for detailed investigations
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