Sudden impulses (SIs) are an important source of ultra low frequency (ULF) wave activity throughout the Earth's magnetosphere. Most SI‐induced ULF wave events have been reported in the dayside ...magnetosphere; it is not clear when and how SIs drive ULF wave activity in the nightside plasma sheet. We examined the ULF response of the nightside plasma sheet to SIs using an ensemble of 13 SI events observed by THEMIS (Timed History of Events and Macroscale Interactions during Substorms) satellites (probes). Only three of these events resulted in ULF wave activity. The periods of the waves are found to be 3.3, 6.0, and 7.6 min. East‐west magnetic and radial electric field perturbations, which typically indicate the toroidal mode, are found to be stronger and can have phase relationships consistent with standing waves. Our results suggest that the two largest‐amplitude ULF responses to SIs in the nightside plasma sheet are tailward‐moving vortices, which have previously been reported, and the dynamic response of cross‐tail currents in the magnetotail to maintain force balance with the solar wind, which has not previously been reported as a ULF wave driver. Both mechanisms could potentially drive standing Alfvén waves (toroidal modes) observed via the field‐line resonance mechanism. Furthermore, both involve frequency selection and a preference for certain driving conditions that can explain the small number of ULF wave events associated with SIs in the nightside plasma sheet.
Key Points
In 3 of 13 SI events, steady ULF wave is induced in the nightside plasma sheet
Field perturbations are usually consistent with standing toroidal Alfven waves
Tailward moving vortices or dynamic response of tail currents may explain
The limitation of nanograined materials is their strong tendency to coarsen at elevated temperatures. As grain size decreases into the nanoscale, grain coarsening occurs at much lower temperatures, ...as low as ambient temperatures for some metals. We discovered that nanometer-sized grains in pure copper and nickel produced from plastic deformation at low temperatures exhibit notable thermal stability below a critical grain size. The instability temperature rises substantially at smaller grain sizes, and the nanograins remain stable even above the recrystallization temperatures of coarse grains. The inherent thermal stability of nanograins originates from an autonomous grain boundary evolution to low-energy states due to activation of partial dislocations in plastic deformation.
The extension of the cosmic-ray spectrum beyond 1 petaelectronvolt (PeV; 10
electronvolts) indicates the existence of the so-called PeVatrons-cosmic-ray factories that accelerate particles to PeV ...energies. We need to locate and identify such objects to find the origin of Galactic cosmic rays
. The principal signature of both electron and proton PeVatrons is ultrahigh-energy (exceeding 100 TeV) γ radiation. Evidence of the presence of a proton PeVatron has been found in the Galactic Centre, according to the detection of a hard-spectrum radiation extending to 0.04 PeV (ref.
). Although γ-rays with energies slightly higher than 0.1 PeV have been reported from a few objects in the Galactic plane
, unbiased identification and in-depth exploration of PeVatrons requires detection of γ-rays with energies well above 0.1 PeV. Here we report the detection of more than 530 photons at energies above 100 teraelectronvolts and up to 1.4 PeV from 12 ultrahigh-energy γ-ray sources with a statistical significance greater than seven standard deviations. Despite having several potential counterparts in their proximity, including pulsar wind nebulae, supernova remnants and star-forming regions, the PeVatrons responsible for the ultrahigh-energy γ-rays have not yet been firmly localized and identified (except for the Crab Nebula), leaving open the origin of these extreme accelerators.
Abstract
Identifying how energy transfer proceeds from macroscales down to microscales in collisionless plasmas is at the forefront of astrophysics and space physics. It provides information on the ...evolution of involved plasma systems and the generation of high-energy particles in the universe. Here we report two cross-scale energy-transfer events observed by NASA’s Magnetospheric Multiscale spacecraft in Earth’s magnetosphere. In these events, hot ions simultaneously undergo interactions with macroscale (~
$${10}^{5}$$
10
5
km) ultra-low-frequency waves and microscale (
$$\sim {10}^{3}$$
~
10
3
km) electromagnetic-ion-cyclotron (EMIC) waves. The cross-scale interactions cause energy to directly transfer from macroscales to microscales, and finally dissipate at microscales via EMIC-wave-induced ion energization. The direct measurements of the energy transfer rate in the second event confirm the efficiency of this cross-scale transfer process, whose timescale is estimated to be roughly ten EMIC-wave periods about (1 min). Therefore, these observations experimentally demonstrate that simultaneous macroscale and microscale wave-ion interactions provide an efficient mechanism for cross-scale energy transfer and plasma energization in astrophysical and space plasmas.
The prevalence of diabetes in China is among the highest in the world. For this reason, findings from the 2016 Global Burden of Disease (GBD) study were used to calculate the burden of hyperglycaemia ...and diabetes in China.
Following the general analytical strategy used in GBD 2016, diabetes prevalence and mortality were analyzed by age and gender. Trends in disability-adjusted life years (DALYs) due to diabetes were assessed in 33 province-level administrative units from 1990 to 2016, and similar data were provided for chronic kidney disease (CKD) related to diabetes and, as an overall summarizing measure, for hyperglycaemia expressed as high fasting plasma glucose (HFPG).
From 1990 to 2016, all-age prevalence of diabetes rose from 3.7% to 6.6%, and all-age diabetes and diabetes-related CKD mortality rates increased by 63.5% and 33.3%, respectively, with both rates increasing more rapidly in diabetes patients aged 15–49 years than in any other age groups. In 2016, HFPG became China's sixth leading cause of DALYs, and the attributable DALYs burden was 1802.3/100,000 population. Although the number of diabetes DALYs increased by 95% from 1990 to 2016, age-standardized diabetes DALYs rates increased by only 2.3%. Also, from 1990 to 2016, rates of age-standardized DALYs due to diabetes decreased in 14 provinces, but increased in 19 provinces. High BMI Scores and diets low in whole grains, nuts and seeds were the most important risk factors for diabetes in 2016.
Diabetes and hyperglycaemia constitute a huge health burden in China. The substantial increase in diabetes-related burden represents an ongoing challenge, given the rapidly ageing Chinese population. Thus, a targeted control and preventative strategy needs to be developed at risk factor level to reduce this burden.
The cross section of the process e+e−→K+K− is measured at a number of center-of-mass energies s from 2.00 to 3.08 GeV with the BESIII detector at the Beijing Electron Positron Collider (BEPCII). The ...results provide the best precision achieved so far. A resonant structure around 2.2 GeV is observed in the cross section line shape. A Breit-Wigner fit yields a mass of M=2239.2±7.1±11.3 MeV/c2 and a width of Γ=139.8±12.3±20.6 MeV, where the first uncertainties are statistical and the second ones are systematic. In addition, the timelike electromagnetic form factor of the kaon is determined at the individual center-of-mass energy points.
We have recently identified and characterized a novel oncogene, maelstrom (MAEL) from 1q24, in the pathogenesis of hepatocellular carcinoma. In this study, MAEL was investigated for its oncogenic ...role in urothelial carcinoma of the bladder (UCB) tumorigenesis/aggressiveness and underlying molecular mechanisms. Here, we report that overexpression of MAEL in UCB is important in the acquisition of an aggressive and/or poor prognostic phenotype. In UCB cell lines, knockdown of MAEL by short hairpin RNA is sufficient to inhibit cell growth, invasiveness/metastasis and suppressed epithelial-mesenchymal transition (EMT), whereas ectopic overexpression of MAEL promoted cell growth, invasive and/or metastatic capacity and enhanced EMT both in vitro and in vivo. We further demonstrate that MAEL could induce UCB cell EMT by downregulating a critical downstream target, the metastasis suppressor 1 (MTSS1) gene, ultimately leading to an increased invasiveness of cancer cells. Notably, overexpression of MAEL in UCB cells substantially enhanced the enrichment of DNA methyltrans-ferase (DNMT)3B and histone deacetylase (HDAC)1/2 on the promoter of the MTSS1, and thereby epigenetically suppressing the MTSS1 transcription. Downregulation of MTSS1 by MAEL in UCB cells is partially dependent on DNMT3B. Furthermore, we identify that beside the gene amplification of MAEL, miR-186 is a key negative regulator of MAEL and downregulation of miR-186 is another important mechanism for MAEL overexpression in UCBs. These data suggest that overexpression of MAEL, caused by gene amplification and/or decreased miR-186, has a critical oncogenic role in UCB pathogenesis by downregulation of MTSS1, and MAEL could be used as a novel prognostic marker and/or effective therapeutic target for human UCB.
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