Results 251 to 260 of about 1,314,904 (274)
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Optical clock intercomparison with $6\times 10^{-19}$ precision in one hour
, 2019Improvements in atom-light coherence are foundational to progress in quantum information science 1 , quantum optics 2 , and precision metrology 3 . Optical atomic clocks require local oscillators with exceptional optical coherence due to the challenge of
E. Oelker +16 more
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Orchestrated transcription of key pathways in Arabidopsis by the circadian clock.
Science, 2000Like most organisms, plants have endogenous biological clocks that coordinate internal events with the external environment. We used high-density oligonucleotide microarrays to examine gene expression in Arabidopsis and found that 6% of the more than ...
S. Harmer +8 more
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Nature Reviews Molecular Cell Biology, 2003
The eukaryotic genome is divided into well-defined DNA regions that are programmed to replicate at different times during S phase. Active genes are generally associated with early replication, whereas inactive genes replicate late. This expression pattern might be facilitated by the differential restructuring of chromatin at the time of replication in ...
Howard Cedar, Alon Goren
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The eukaryotic genome is divided into well-defined DNA regions that are programmed to replicate at different times during S phase. Active genes are generally associated with early replication, whereas inactive genes replicate late. This expression pattern might be facilitated by the differential restructuring of chromatin at the time of replication in ...
Howard Cedar, Alon Goren
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AJN, American Journal of Nursing, 1970
| '~^?~ / Iivt,pitals and nursing homes, and worst of all, by their nursing staffs. :zji |g j, jtiicEnter any nursing home and you will see loudspeakers, intercoms, and television sets everywhere. But ^^ & ^ mt i XM n' ~how many patients have access to a clock and a calendar, particularly if they are bedridden and cannot navigate on their own?
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| '~^?~ / Iivt,pitals and nursing homes, and worst of all, by their nursing staffs. :zji |g j, jtiicEnter any nursing home and you will see loudspeakers, intercoms, and television sets everywhere. But ^^ & ^ mt i XM n' ~how many patients have access to a clock and a calendar, particularly if they are bedridden and cannot navigate on their own?
openaire +3 more sources
Light Clocks and the Clock Hypothesis
Foundations of Physics, 2013The clock hypothesis of relativity theory equates the proper time experienced by a point particle along a timelike curve with the length of that curve as determined by the metric. Is it possible to prove that particular types of clocks satisfy the clock hypothesis, thus genuinely measure proper time, at least approximately?
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Frequency ratio measurements at 18-digit accuracy using an optical clock network
Nature, 2021Kyle Martha I. Tobias Samuel M. Sarah L. Jwo-Sy Jean-Da Beloy Bodine Bothwell Brewer Bromley Chen Deschêne +35 more
semanticscholar +1 more source
Geodesy and metrology with a transportable optical clock
, 2017Optical atomic clocks, due to their unprecedented stability1–3 and uncertainty3–6, are already being used to test physical theories7,8 and herald a revision of the International System of Units9,10.
J. Grotti +23 more
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Composite clock including a Cs clock, a H-maser clock and a VCO.
2009 IEEE International Frequency Control Symposium Joint with the 22nd European Frequency and Time forum, 2009We present the project of a composite clock, that will combine a cesium standard, a hydrogen maser standard, and a voltage controlled oscillator in order to provide an output signal that would combine the respective quality of each of the component clocks, the long-term stability for the Cs clock, the mid-term stability for the H-maser and the the ...
P.M. Mbaye +3 more
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Entrainment of the circadian clock in the liver by feeding.
Science, 2001Circadian rhythms of behavior are driven by oscillators in the brain that are coupled to the environmental light cycle. Circadian rhythms of gene expression occur widely in peripheral organs.
K. Stokkan +4 more
semanticscholar +1 more source
Science, 1999
It is well known that as we age, we need fewer hours of sleep and wake up much earlier in the morning. This change has been attributed to a shortening of the period of the human circadian pacemaker. However, Robert Moore explains in a Perspective that new findings ( Czeisler et al .) demonstrate that it is not the pacemaker itself ...
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It is well known that as we age, we need fewer hours of sleep and wake up much earlier in the morning. This change has been attributed to a shortening of the period of the human circadian pacemaker. However, Robert Moore explains in a Perspective that new findings ( Czeisler et al .) demonstrate that it is not the pacemaker itself ...
openaire +3 more sources