Nature, 21May 2020, No.581No.7808
Nature, may 2, 20201,Vol.58 1, No.7808.
Physics physics
A cold, huge and rotating disk galaxy 65438+500 million years after the Big Bang.
Early disk galaxies challenged the traditional model of galaxy formation.
▲ Authors: Marcel Nearman, J Xavier Prochaska, Nisim Kanekar, Mark Raphaelsky, etc.
▲ link:/articles/s 41586-020-2276-y
▲ abstract
In the traditional model of galaxy formation, massive disk galaxies like the Milky Way are expected to form in the later stage. Recent numerical simulations show that such a galaxy may have been formed by accretion and merger of cold matter as early as 654.38 billion years after BIGBANG.
By detecting the absorption and recognition of quasar light, the author reports a galaxy with a red shift of 4.2603. These observations show that the radiation comes from the gas in a cold, dusty rotating disk with a rotating speed of about 272 kilometers per second. The researchers detected the emission of carbon monoxide in the galaxy, and the molecular weight obtained was consistent with the estimated ionized carbon emission of about 72 billion solar masses.
When the universe is only 654.38+0.5 billion years old, the existence of such a huge and rotationally supported cold disk galaxy is conducive to the formation of cold mode accretion or merger, although its large rotation speed and large cold gas content are still difficult to be reproduced by most numerical simulations.
▲ abstract
In the traditional galaxy formation model, a massive disk galaxy like the Milky Way is expected to form in the later stage, but recent numerical simulation shows that this galaxy may be formed by accretion and merger of cold matter 10 billion years after the Big Bang. Here, we report the imaging with a resolution of about 1.3 kilosecond, which comes from the 158 micron emission line of single ionized carbon, the far infrared dust continuous spectrum and the near ultraviolet continuous spectrum emission from a galaxy with a red shift of 4.2603, which is determined by detecting its absorption of quasar light. These observations show that this emission comes from the gas in a cold, dusty disk rotating at a speed of about 272 kilometers per second. The detection of carbon monoxide emissions in the Milky Way has produced a molecular mass, which is consistent with the estimate of the mass of about 72 billion suns emitted by ionized carbon. When the universe is only 65438+500 million years old, there is such a huge rotating-supported cold disk galaxy, which is beneficial to accretion or merger of cold modes, although its large rotating speed and a large amount of cold gas are still difficult to reproduce by most numerical simulations.
Quantum entanglement between atoms and molecules
Quantum entanglement between atoms and molecules
▲ Authors: Yihenglin, David R. Leibrandt, Dietrich Leibfried, Chin-Wen Chou, etc.
▲ link:/articles/s 41586-020-2257-1
▲ abstract
Traditional information processors convert, process, store and transmit information between different physical carriers.
The author has proved the entanglement between the rotating state of 40CaH+ molecular ion and the internal state of 40Ca+ atomic ion. They extend the methods used in quantum logic spectroscopy for pure state initialization, laser operation and molecular ion state reading.
The quantum coherence of coulomb coupling motion between atoms and molecular ions makes the subsequent entanglement operation possible. The frequency of qubits in this molecule is 13.4 kHz or 855 GHz, which highlights the versatility of molecular qubits.
The author demonstrates how molecules transfer quantum information between qubits with different frequencies, thus realizing a mixed quantum system. They expect that this method of molecular quantum control and measurement can be applied to quantum information science, quantum sensors, basic and applied physics and controlled quantum chemistry.
▲ abstract
Traditional information processors convert information between different physical carriers for processing, storage and transmission. Here we demonstrate the entanglement between the rotational dynamics of 40CaH+ molecular ions and the internal states of 40Ca+ atomic ions. We extend the methods of pure state initialization, laser manipulation and state reading of molecular ions in quantum logic spectroscopy. The quantum coherence of Coulomb coupling motion between atoms and molecular ions makes the subsequent entanglement operation possible. The addressed qubits in molecules have a frequency of 13.4 kHz 1 or 855 GHz, which highlights the versatility of molecular qubits. Our work shows how molecules can convert quantum information between qubits with different frequencies to realize a mixed quantum system. We expect that our quantum control and molecular measurement methods will be applied in quantum information science, quantum sensors, basic and applied physics and controlled quantum chemistry.
bionics
Hemispherical Perovskite Nanowire Array Retinal bionic eye
Machine bionic eye
▲ Authors: Gu, Swanadi Podda, Yuan, Long, Ali Javi, Fan Zhiyong, etc.
▲ link:/articles/s 41586-020-2285-x
▲ abstract
The human eye has special image sensing characteristics, such as extremely wide field of view, high resolution and low aberration.
The author describes a high-density nanowire array composed of electrochemical eye and hemispherical retina to simulate photoreceptors on human retina. The design of the device is highly similar to the structure of human eyes, and it is possible to achieve high imaging resolution when machining a single nanowire.
In addition, the author also demonstrates its image sensing function by reconstructing the optical mode projected on the bionic device. The author said that this research will promote the wide application of bionic photosensitive devices.
▲ abstract
The human eye has special image sensing characteristics, such as extremely wide field of vision, high resolution and low aberration sensitivity. Here, we show an electrochemical eye, which has a hemispherical retina made of a high-density nanowire array, imitating the photoreceptors on the human retina. The device design has a high degree of structural similarity with human eyes, and high imaging resolution can be achieved when a single nanowire is electrically addressed. In addition, we demonstrate the image sensing function of our bionic equipment by reconstructing the optical patterns projected onto the equipment. This work may lead to bionic photosensitive devices, which can be used in a wide range of technical applications.
physical chemistry
physical chemistry
Short-range order and its effect on entropy alloy in CrCoNi
Effect of short-range ordered structure in CrCoNi on properties of entropy alloy
▲ Authors: Zhang Ruopeng, Shi Tengzhao, Ding Jun, Yan Chong, Tao Jia, Andrew Mina, etc.
▲ link:/articles/s 41586-020-2275-z
▲ abstract
The traditional metal alloy is a mixture of elements, in which a few atoms tend to be randomly distributed below its solubility limit and form a second phase above its solubility limit.
The structural characteristics of middle entropy alloy observed by energy filtering transmission electron microscope are reported, which can be attributed to short-range arrangement. The increase of this sequence will lead to higher superimposed fault energy and hardness.
These results show that the local order degree in nanometer scale can be adjusted by thermomechanical treatment, which provides a new way to adjust the mechanical properties of medium and high entropy alloys.
▲ abstract
Traditional metal alloys are mixtures of elements, in which a few kinds of atoms tend to be randomly distributed if they are below their solubility limits, or form a second phase if they are above their solubility limits. Here, we report the observation that the structural characteristics are attributed to the short-range ordered entropy alloy in CrCoNi by using energy filtering transmission electron microscope. This increase in order leads to higher stacking fault energy and hardness. These findings show that the degree of local order in nanometer scale can be customized by thermodynamic treatment, which provides a new way to adjust the mechanical properties of medium entropy and high entropy alloys.
earth sciences
Types and trends of snow masses in the northern hemisphere from 1980 to 20 18
1980 to 20 18 snow conditions in the northern hemisphere.
▲ Authors: Jouni Pulliainen, Kariluojus, Chris Derksen, Lawrence Mudryk, Johannes Norberg, etc.
▲ link:/articles/s 41586-020-2258-0
▲ abstract
Global warming has greatly reduced the coverage and duration of snow and ice in the northern hemisphere. Using the new GlobSnow 3.0 data set, the author concludes that the average annual maximum snowfall in the northern hemisphere 1980 ~ 20 18 is 306.23.5 billion tons.
The author quantified the data in March (the closest to the peak of snow), covering non-alpine areas over 40 N, and most importantly, included the deviation correction based on field snow observation.
The author compares the estimate of GlobSnow 3.0 with three independent snow quantity estimates, and each estimate has or does not have deviation correction. In the four data sets, the range of deviation correction is reduced from 243.32 billion tons to 338 billion tons to 284.6 billion tons to 306.2 billion tons-the uncertainty is reduced from 3.3% to 7.4%.
The author found that in the 39-year satellite records, different continents have different trends. For example, the snowfall in North America decreases by 46 billion tons every 10 year, while the trend in Europe and Asia can be ignored; The two continents show a high degree of regional differences. This study is helpful to better evaluate the role of seasonal snowfall in the earth's energy, water and carbon budget.
▲ abstract
The warming surface temperature has greatly reduced the scope and duration of snow in the northern hemisphere. Here, we use the new Glob Snow 3.0 data set to show that the average maximum snow amount in the northern hemisphere1980–2018 is 30,623.5 billion tons (gigatons). Our quantification is aimed at March (the month closest to the peak of snow amount), covering non-alpine areas above 40 north latitude, and most importantly, it includes deviation correction based on field snow observation. We compared our estimated value of GlobSnow 3.0 with three independent estimated values of snow amount, and each estimated value was corrected with and without deviation. Between the four data sets, the range of deviation correction is reduced from 2433-3380 gigatons (average 2867) to 2846-3062 gigatons (average 2938), and the uncertainty is reduced from 33% to 7.4%. Based on our deviation-corrected GlobSnow 3.0 estimation, we have found different continental trends in 39 years of satellite records. For example, the amount of snow in North America decreases by 4.6 billion tons every ten years, but the trend in Eurasia can be ignored; Both continents show high regional variability. Our results can better estimate the role of seasonal snow in the earth's energy, water and carbon budget.
palaeoanthropology
palaeoanthropology
Early paleolithic homo sapiens in Bacho Kiro cave, Bulgaria
The earliest Homo sapiens in the late Paleolithic came from Bulgaria.
▲ Authors: Jean-Jacques Hublin, Nikolai Silakov, Tesenka Chanova, etc.
▲ link:/articles/s 41586-020-2259-z
▲ abstract
In the transitional period from the middle to the late Paleolithic period in Europe, Homo sapiens in Africa replaced the local Neanderthals and absorbed them to some extent.
The author reports the discovery and direct dating of human remains related to the early Paleolithic cultural relics, which came from the Luo cave in Baqiaoqi.
The author identified these findings as Homo sapiens through the morphological analysis of the mitochondrial DNA of a tooth and several ancient human bone fragments identified by protein's omics, and connected the expansion of science and technology in the early Paleolithic with the spread of Homo sapiens to the mid-latitude region of Eurasia 45,000 years ago.
This excavation unearthed a large number of bone products, including pendants made of cave bear teeth, reminiscent of the last Neanderthals in Western Europe. These findings are consistent with previous models, which were based on multiple migrations between Homo sapiens and Neanderthals.
▲ abstract
The transition from the middle to the late Paleolithic period in Europe witnessed the replacement and partial absorption of local Neanderthals by Homo sapiens from Africa. Here, we report the discovery and direct dating of human remains related to the early Paleolithic age found in the Luo Cave in Bacciocchi. Through the morphological analysis of mitochondrial DNA of a tooth and several human bone fragments screened by protein Group, these findings are attributed to Homo sapiens, and the expansion of early Paleolithic technology is related to the spread of Homo sapiens to the mid-latitude region of Eurasia 45,000 years ago. A large number of bone products were excavated, including pendants made of cave bear teeth, which are reminiscent of the pendants made by the last Neanderthals in western Europe. These findings are consistent with the model based on the arrival of Dobio Homo sapiens in Europe and contact with the declining Neanderthals.