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Scientists develop method for seasonal prediction of western wildfires 新闻
来源平台:National Center of Atmospheric Research. 发布日期:2022
作者:  admin
收藏  |  浏览/下载:4/0  |  提交时间:2022/06/24
New NCAR-Wyoming supercomputer to accelerate scientific discovery 新闻
来源平台:National Center of Atmospheric Research. 发布日期:2021
作者:  admin
收藏  |  浏览/下载:13/0  |  提交时间:2021/02/10
High-speed atomic force microscopy takes on intrinsically disordered proteins 新闻
来源平台:EurekAlert. 发布日期:2020
作者:  admin
收藏  |  浏览/下载:9/0  |  提交时间:2021/01/06
New approach can improve COVID-19 predictions worldwide 新闻
来源平台:EurekAlert. 发布日期:2020
作者:  admin
收藏  |  浏览/下载:0/0  |  提交时间:2020/12/22
A neural network learns when it should not be trusted 新闻
来源平台:EurekAlert. 发布日期:2020
作者:  admin
收藏  |  浏览/下载:8/0  |  提交时间:2020/11/20
A surprising range of climate events may be predictable years in advance 新闻
来源平台:National Center of Atmospheric Research. 发布日期:2020
作者:  admin
收藏  |  浏览/下载:6/0  |  提交时间:2020/08/24
Human influence has intensified extreme precipitation in North America 期刊论文
PROCEEDINGS OF THE NATIONAL ACADEMY OF SCIENCES OF THE UNITED STATES OF AMERICA, 2020, 117 (24) : 13308-13313
作者:  Kirchmeier-Young, Megan C.;  Zhang, Xuebin
收藏  |  浏览/下载:6/0  |  提交时间:2020/06/09
extreme precipitation  attribution  regional climate change  
Fundamental bounds on the fidelity of sensory cortical coding 期刊论文
NATURE, 2020
作者:  Rempel, S.;  Gati, C.;  Nijland, M.;  Thangaratnarajah, C.;  Karyolaimos, A.;  de Gier, J. W.;  Guskov, A.;  Slotboom, D. J.
收藏  |  浏览/下载:17/0  |  提交时间:2020/07/03

How the brain processes information accurately despite stochastic neural activity is a longstanding question(1). For instance, perception is fundamentally limited by the information that the brain can extract from the noisy dynamics of sensory neurons. Seminal experiments(2,3) suggest that correlated noise in sensory cortical neural ensembles is what limits their coding accuracy(4-6), although how correlated noise affects neural codes remains debated(7-11). Recent theoretical work proposes that how a neural ensemble'  s sensory tuning properties relate statistically to its correlated noise patterns is a greater determinant of coding accuracy than is absolute noise strength(12-14). However, without simultaneous recordings from thousands of cortical neurons with shared sensory inputs, it is unknown whether correlated noise limits coding fidelity. Here we present a 16-beam, two-photon microscope to monitor activity across the mouse primary visual cortex, along with analyses to quantify the information conveyed by large neural ensembles. We found that, in the visual cortex, correlated noise constrained signalling for ensembles with 800-1,300 neurons. Several noise components of the ensemble dynamics grew proportionally to the ensemble size and the encoded visual signals, revealing the predicted information-limiting correlations(12-14). Notably, visual signals were perpendicular to the largest noise mode, which therefore did not limit coding fidelity. The information-limiting noise modes were approximately ten times smaller and concordant with mouse visual acuity(15). Therefore, cortical design principles appear to enhance coding accuracy by restricting around 90% of noise fluctuations to modes that do not limit signalling fidelity, whereas much weaker correlated noise modes inherently bound sensory discrimination.


A microscopy system that enables simultaneous recording from hundreds of neurons in the mouse visual cortex reveals that the brain enhances its coding capacity by representing visual inputs in dimensions perpendicular to correlated noise.


  
Washington Update: March 4, 2020 新闻
来源平台:National Center of Atmospheric Research. 发布日期:2020
作者:  admin
收藏  |  浏览/下载:4/0  |  提交时间:2020/06/16
Coherent electrical control of a single high-spin nucleus in silicon 期刊论文
NATURE, 2020, 579 (7798) : 205-+
作者:  Dedoussi, Irene C.;  Eastham, Sebastian D.;  Monier, Erwan;  Barrett, Steven R. H.
收藏  |  浏览/下载:10/0  |  提交时间:2020/07/03

Nuclear spins are highly coherent quantum objects. In large ensembles, their control and detection via magnetic resonance is widely exploited, for example, in chemistry, medicine, materials science and mining. Nuclear spins also featured in early proposals for solid-state quantum computers(1) and demonstrations of quantum search(2) and factoring(3) algorithms. Scaling up such concepts requires controlling individual nuclei, which can be detected when coupled to an electron(4-6). However, the need to address the nuclei via oscillating magnetic fields complicates their integration in multi-spin nanoscale devices, because the field cannot be localized or screened. Control via electric fields would resolve this problem, but previous methods(7-9) relied on transducing electric signals into magnetic fields via the electron-nuclear hyperfine interaction, which severely affects nuclear coherence. Here we demonstrate the coherent quantum control of a single Sb-123 (spin-7/2) nucleus using localized electric fields produced within a silicon nanoelectronic device. The method exploits an idea proposed in 1961(10) but not previously realized experimentally with a single nucleus. Our results are quantitatively supported by a microscopic theoretical model that reveals how the purely electrical modulation of the nuclear electric quadrupole interaction results in coherent nuclear spin transitions that are uniquely addressable owing to lattice strain. The spin dephasing time, 0.1 seconds, is orders of magnitude longer than those obtained by methods that require a coupled electron spin to achieve electrical driving. These results show that high-spin quadrupolar nuclei could be deployed as chaotic models, strain sensors and hybrid spin-mechanical quantum systems using all-electrical controls. Integrating electrically controllable nuclei with quantum dots(11,12) could pave the way to scalable, nuclear- and electron-spin-based quantum computers in silicon that operate without the need for oscillating magnetic fields.