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共有 105621 条符合本次的查询结果, 用时 2.0429616 秒

181. Warm-hot baryons comprise 5-10 per cent of filaments in the cosmic web.

作者: Dominique Eckert.;Mathilde Jauzac.;HuanYuan Shan.;Jean-Paul Kneib.;Thomas Erben.;Holger Israel.;Eric Jullo.;Matthias Klein.;Richard Massey.;Johan Richard.;Céline Tchernin.
来源: Nature. 2015年528卷7580期105-7页
Observations of the cosmic microwave background indicate that baryons account for 5 per cent of the Universe's total energy content. In the local Universe, the census of all observed baryons falls short of this estimate by a factor of two. Cosmological simulations indicate that the missing baryons have not condensed into virialized haloes, but reside throughout the filaments of the cosmic web (where matter density is larger than average) as a low-density plasma at temperatures of 10(5)-10(7) kelvin, known as the warm-hot intergalactic medium. There have been previous claims of the detection of warm-hot baryons along the line of sight to distant blazars and of hot gas between interacting clusters. These observations were, however, unable to trace the large-scale filamentary structure, or to estimate the total amount of warm-hot baryons in a representative volume of the Universe. Here we report X-ray observations of filamentary structures of gas at 10(7) kelvin associated with the galaxy cluster Abell 2744. Previous observations of this cluster were unable to resolve and remove coincidental X-ray point sources. After subtracting these, we find hot gas structures that are coherent over scales of 8 megaparsecs. The filaments coincide with over-densities of galaxies and dark matter, with 5-10 per cent of their mass in baryonic gas. This gas has been heated up by the cluster's gravitational pull and is now feeding its core. Our findings strengthen evidence for a picture of the Universe in which a large fraction of the missing baryons reside in the filaments of the cosmic web.

182. Overflow metabolism in Escherichia coli results from efficient proteome allocation.

作者: Markus Basan.;Sheng Hui.;Hiroyuki Okano.;Zhongge Zhang.;Yang Shen.;James R Williamson.;Terence Hwa.
来源: Nature. 2015年528卷7580期99-104页
Overflow metabolism refers to the seemingly wasteful strategy in which cells use fermentation instead of the more efficient respiration to generate energy, despite the availability of oxygen. Known as the Warburg effect in the context of cancer growth, this phenomenon occurs ubiquitously for fast-growing cells, including bacteria, fungi and mammalian cells, but its origin has remained unclear despite decades of research. Here we study metabolic overflow in Escherichia coli, and show that it is a global physiological response used to cope with changing proteomic demands of energy biogenesis and biomass synthesis under different growth conditions. A simple model of proteomic resource allocation can quantitatively account for all of the observed behaviours, and accurately predict responses to new perturbations. The key hypothesis of the model, that the proteome cost of energy biogenesis by respiration exceeds that by fermentation, is quantitatively confirmed by direct measurement of protein abundances via quantitative mass spectrometry.

183. Measuring entanglement entropy in a quantum many-body system.

作者: Rajibul Islam.;Ruichao Ma.;Philipp M Preiss.;M Eric Tai.;Alexander Lukin.;Matthew Rispoli.;Markus Greiner.
来源: Nature. 2015年528卷7580期77-83页
Entanglement is one of the most intriguing features of quantum mechanics. It describes non-local correlations between quantum objects, and is at the heart of quantum information sciences. Entanglement is now being studied in diverse fields ranging from condensed matter to quantum gravity. However, measuring entanglement remains a challenge. This is especially so in systems of interacting delocalized particles, for which a direct experimental measurement of spatial entanglement has been elusive. Here, we measure entanglement in such a system of itinerant particles using quantum interference of many-body twins. Making use of our single-site-resolved control of ultracold bosonic atoms in optical lattices, we prepare two identical copies of a many-body state and interfere them. This enables us to directly measure quantum purity, Rényi entanglement entropy, and mutual information. These experiments pave the way for using entanglement to characterize quantum phases and dynamics of strongly correlated many-body systems.

184. Quantum physics: Getting the measure of entanglement.

作者: Steven Rolston.
来源: Nature. 2015年528卷7580期48-9页

185. In retrospect: A century of phage lessons.

作者: Forest Rohwer.;Anca M Segall.
来源: Nature. 2015年528卷7580期46-8页

186. Nuclear physics: Close encounters of the alpha kind.

作者: Sofia Quaglioni.
来源: Nature. 2015年528卷7580期42-3页

187. Lisa Jardine (1944-2015).

作者: Anthony Grafton.
来源: Nature. 2015年528卷7580期40页

188. Mining disaster: Restore habitats now.

作者: Jhonny Capichoni Massante.
来源: Nature. 2015年528卷7580期39页

189. Higher education: Star universities in the Muslim world.

作者: Javaid Laghari.
来源: Nature. 2015年528卷7580期39页

190. Microbiology: Microbiome studies need local leaders.

作者: Victor S Pylro.;Daniel K Morais.;Luiz F W Roesch.
来源: Nature. 2015年528卷7580期39页

191. Mining disaster: Huge species impact.

作者: Markus Lambertz.;Jorge A Dergam.
来源: Nature. 2015年528卷7580期39页

192. Conservation: It is rational to protect Antarctica.

作者: Jennifer Jacquet.;Cassandra Brooks.
来源: Nature. 2015年528卷7580期39页

193. Agricultural policy: Govern our soils.

作者: Luca Montanarella.
来源: Nature. 2015年528卷7580期32-3页

194. Chemistry: Reuse water pollutants.

作者: Wen-Wei Li.;Han-Qing Yu.;Bruce E Rittmann.
来源: Nature. 2015年528卷7580期29-31页

195. The inside story on wearable electronics.

作者: Elizabeth Gibney.
来源: Nature. 2015年528卷7580期26-8页

196. How to build a better PhD.

作者: Julie Gould.
来源: Nature. 2015年528卷7580期22-5页

197. Terrorism science: 5 insights into jihad in Europe.

作者: Declan Butler.
来源: Nature. 2015年528卷7580期20-1页

198. UK scientists celebrate slight rise in research budget.

作者: Elizabeth Gibney.
来源: Nature. 2015年528卷7580期20页

199. Brain study seeks roots of suicide.

作者: Sara Reardon.
来源: Nature. 2015年528卷7580期19页

200. Artificial intelligence called in to tackle LHC data deluge.

作者: Davide Castelvecchi.
来源: Nature. 2015年528卷7580期18-9页
共有 105621 条符合本次的查询结果, 用时 2.0429616 秒