Results 311 to 320 of about 1,354,268 (327)

Atomic clock performance enabling geodesy below the centimetre level

Nature, 2018
The passage of time is tracked by counting oscillations of a frequency reference, such as Earth’s revolutions or swings of a pendulum. By referencing atomic transitions, frequency (and thus time) can be measured more precisely than any other physical ...
W. McGrew, W. McGrew, Xiaogang Zhang, Xiaogang Zhang, R. Fasano, R. Fasano, S. Schäffer, S. Schäffer, K. Beloy, D. Nicolodi, D. Nicolodi, Roger Brown, Roger Brown, N. Hinkley, N. Hinkley, G. Milani, G. Milani, M. Schioppo, M. Schioppo, T. Yoon, T. Yoon, A. Ludlow, A. Ludlow   +22 more
semanticscholar   +1 more source

Clock drawing test

Practical Neurology
The clock drawing test is one of the most common screening instruments for dementia. It is easy and fast to administer and provides a straightforward way to assess a range of cognitive domains.
Fernanda Lustosa Cabral Gomez, P. Bertolucci   +1 more
semanticscholar   +1 more source

Optical clock intercomparison with $6\times 10^{-19}$ precision in one hour

, 2019
Improvements 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, R. Hutson, C. Kennedy, L. Sonderhouse, T. Bothwell, A. Goban, D. Kedar, C. Sanner, J. Robinson, G. E. Marti, D. Matei, T. Legero, M. Giunta, R. Holzwarth, F. Riehle, U. Sterr, J. Ye   +16 more
semanticscholar   +1 more source

Orchestrated transcription of key pathways in Arabidopsis by the circadian clock.

Science, 2000
Like 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, J. Hogenesch, M. Straume, H. Chang, B. Han, Tong Zhu, X. Wang, J. Kreps, S. Kay   +8 more
semanticscholar   +1 more source

Frequency ratio measurements at 18-digit accuracy using an optical clock network

Nature, 2021
Kyle Martha I. Tobias Samuel M. Sarah L. Jwo-Sy Jean-Da Beloy Bodine Bothwell Brewer Bromley Chen Deschêne, K. Beloy, M. I. Bodine, T. Bothwell, S. Brewer, S. Bromley, Jwo-Sy Chen, J. Deschênes, S. Diddams, R. Fasano, T. Fortier, Y. Hassan, D. Hume, D. Kedar, C. Kennedy, I. Khader, A. Koepke, D. Leibrandt, H. Leopardi, A. Ludlow, W. McGrew, W. Milner, N. Newbury, D. Nicolodi, E. Oelker, T. Parker, J. Robinson, S. Romisch, S. A. Schäffer, J. Sherman, L. Sinclair, L. Sonderhouse, W. Swann, Jian Yao, Jun Ye, Xiaogang Zhang   +35 more
semanticscholar   +1 more source

Geodesy and metrology with a transportable optical clock

, 2017
Optical 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, S. Koller, S. Vogt, S. Häfner, U. Sterr, C. Lisdat, H. Denker, C. Voigt, L. Timmen, A. Rolland, F. Baynes, H. Margolis, M. Zampaolo, P. Thoumany, M. Pizzocaro, B. Rauf, F. Bregolin, A. Tampellini, P. Barbieri, M. Zucco, G. Costanzo, C. Clivati, F. Levi, D. Calonico   +23 more
semanticscholar   +1 more source

Dating of the human-ape splitting by a molecular clock of mitochondrial DNA

Journal of Molecular Evolution, 2005
M. Hasegawa, H. Kishino, T. Yano
semanticscholar   +1 more source

DNA methylation-based biomarkers and the epigenetic clock theory of ageing

Nature reviews genetics, 2018
S. Horvath, K. Raj
semanticscholar   +1 more source