Electron flux measurements outside geosynchronous orbit (GSO) obtained by the BeiDa Imaging Electron Spectrometer instrument on board a 55° inclined GSO satellite and inside GSO obtained by the Van ...Allen Probes are analyzed to investigate the temporal and spatial evolutions of the substorm injection region. In 1 year data started from October 2015, 63 injection events are identified. First, our study shows that the injection signatures can be detected in a large radial extent in one single event, for example, from L ∼ 4.1 to L ∼ 9.3. Second, injection onset times are derived from the energy dispersion of particle injection signatures of each satellite. The difference of the onset times among satellites reveals that the injection boundary, termed as “injection front” in this paper, can propagate both earthward and tailward with a speed varying from a few km/s to ∼100 km/s. Third, evolutions of the upper‐cutoff magnetic moments (μuc) of injected electrons are analyzed, upon which the injection events are classified into two categories. In one category, the μuc observed by two radially separated satellites are equal taking into account the error caused by the finite width of energy channels, whereas in the other category, μuc at lower L shells are smaller than those at higher L shells.
Key Points
Substorm injection front can propagate both earthward (34 cases) and tailward (49 cases), with a speed varying from a few km/s to ∼100 km/s
Studies on the upper‐cutoff magnetic moment indicate that substorm injections may be divided into two types: adiabatic and nonadiabatic injection
Statistical study is conducted on 63 substorm injection events from L ∼ 4 to L ∼ 10, which are identified from 1 year flux measurements
The air pollution index (API) sequences in 10 cities in northern China and the synoptic pressure patterns during autumn and winter from 2002 to 2006 were analyzed with diagnostic and statistical ...methods. The results showed that the air qualities in northern China had a prominent correlation with the pressure systems. It revealed that (a) the increasing phase of API was associated with high pressure and the successive low pressure, (b) the preceding part of front (i.e. the retral part of low pressure) was associated with the maximum of API values during a cycle of air pollution process, (c) the pressure systems with high gradient led to the decrease of API, and (d) the synoptic pressure patterns and their evolvements were the main causes of regional air pollution processes. These relations can be used to analyze the variation characteristics and mechanism of regional atmosphere pollution process, and provide important basis for the qualitative prediction, control, and management of regional air pollution problems.
Summary
Since the first report of porcine kobuvirus (PKV) in 2008, it has been confirmed that PKV is widely present in several countries and plays an important role in diarrhoea outbreak in pigs. ...Studies have shown that the biggest difference among PKVs is the presence or absence of a specific 30‐amino acid (aa) sequence in the 2B region of the polyprotein gene. Based on this unique feature, most PKV sequences could be divided into two groups (Group 1 without deletion and Group 2 with deletion), but a few sequences did not follow this rule due to possible recombination. In this study, two PKV genome sequences, designated JXAT2015 (8,123 nucleotide) and JXJC2015 (8,120 nucleotide), were identified on two different commercial swine farms with the severe diarrhoea outbreak accompanying with highly PKV infection (90%, 18/20) and moderate infection (40%, 8/20) of porcine bocavirus 1 (PBoV1) in Jiangxi province of China. Sequence analysis based on the polyprotein gene showed that they shared low nucleotide similarity (86.3%–88.1%) with other known PKVs. Although both possessed the 30‐aa deletion in the 2B region, phylogenetic analysis showed that JXJC2015 was distinct from Group 1 and even Group 2, and formed a new Group (designated Group 3). The findings of this study further revealed genetic diversity and the possible pathogenic role of PKV in conjunction with other pathogens in piglets.
Deposition current during fabrication plays an important role in the microstructure and properties of titanium alloy components prepared by multi-wire arc additive manufacturing (MWAAM) technology. ...In this study, Ti basic heterogeneous alloy with Ti-6.5Al-3.5Mo-1.5Zr-0.3Si (TC11) as the main component was deposited using the MWAAM method with the deposition current ranging from 360 A to 400 A. The effects of deposition current on the microstructural evolution, mechanical and corrosion properties of the MWAAM titanium alloys were investigated, and the process-microstructure-property relationship was analyzed. The results show that the microstructure of as-received Ti basic heterogeneous alloy was mainly composed of lamellar primary α phase (αP) and transformed β phase (βT), and increasing the deposition current during the MWAAM process would result in the increased width of α phase and the decreased aspect ratio of α phase. The mechanical properties of MWAAM-deposited specimens decrease with increasing current, which means that phase composition played a dominant role in determining hardness. When increasing the deposition current during the MWAAM process the ultimate tensile strength (UTS) decreased from 843.75 to 804.38 MPa. The MWAAM-deposited Ti basic heterogeneous alloy featured excellent corrosion properties, the corrosion potential of the best specimen was − 311 mV SCE and the corrosion current density was 1.23 × 10−8 Acm−2. This study provides a better understanding of the effect of deposition current on the targeted deposition property in the MWAAM process, which will contribute to future process control, improvement and optimization.
Highlights ► We focused on the secondary injury in remote loci connected to the infarction. ► Renovascular hypertensive rats were used to study secondary injury following stroke. ► Exogenous netrin-1 ...could rescue neuron loss by attenuating the secondary apoptosis. ► Insufficiency of endogenous netrin-1 could be a mechanism of secondary injury.
Magnetic holes have been widely observed in various space plasma systems. The origin of magnetic holes and their influence to background plasma are under debate. In this paper, we show a ...kinetic‐scale electron vortex magnetic hole in a nonideal region of an active X line, which was observed by the Magnetospheric Multiscale mission at the dayside magnetopause. Intense current and nonideal electric field in the electron frame were observed within the magnetic hole, which led to a strong energy dissipation. Thus, the electron vortex magnetic hole probably provided an additional energy dissipation channel besides the electron diffusion region adjacent to the hole. We suggest that magnetic reconnection provided favorable conditions for the formation of this kinetic‐scale magnetic hole and is an important source of magnetic holes in space plasma.
Key Points
First evidence for reconnection‐driven kinetic‐scale magnetic hole
The hole was associated with an electron vortex and was observed in the vicinity of an electron diffusion region
The hole probably provided an additional energy dissipation channel besides the electron diffusion region
We aimed to explore the real experience of patients after liver transplantation in the intensive care unit (ICU).Objective sampling method was used to select patients transferred to the ICU in 10 ...hospitals in Zhuhai from May 2018 to August 2020. Patients need liver transplantation due to advanced liver cancer and decompensated cirrhosis. The eligibility criteria of patients mainly included liver transplant patients who were clear-minded and willing to participate in the study and had stayed in ICU. Phenomenological research methods and in-depth interviews were used in this qualitative study.The results showed that the true experience of patients after liver transplantation during ICU stay was summarized into four themes. The strengths of our qualitative research are that we can find the trend from a phenomenon through interviews and other methods to provide a directional foundation for future quantitative research. Its limitations are that it requires a lot of manpower and time, and its objectivity and universality are limited.Hospitalization experience in the ICU may lead to many negative experiences for liver transplant patients. Nurses should fully understand and pay attention to the psychological changes in patients. Nurses should take effective targeted measures to reduce or eliminate patients' fear of ICU stay and promote rehabilitation.
Abstract
For decades, supernova remnants (SNRs) have been considered the prime sources of Galactic cosmic rays (CRs). But whether SNRs can accelerate CR protons to PeV energies and thus dominate CR ...flux up to the knee is currently under intensive theoretical and phenomenological debate. The direct test of the ability of SNRs to operate as CR PeVatrons can be provided by ultrahigh-energy (UHE;
E
γ
≥ 100 TeV)
γ
-rays. In this context, the historical SNR Cassiopeia A (Cas A) is considered one of the most promising targets for UHE observations. This paper presents the observation of Cas A and its vicinity by the LHAASO KM2A detector. The exceptional sensitivity of LHAASO KM2A in the UHE band, combined with the young age of Cas A, enabled us to derive stringent model-independent limits on the energy budget of UHE protons and nuclei accelerated by Cas A at any epoch after the explosion. The results challenge the prevailing paradigm that Cas A–type SNRs are major suppliers of PeV CRs in the Milky Way.
The Large High Altitude Air Shower Observatory (LHAASO) is a new generation hybrid cosmic ray observatory which is expected to reveal the mystery of the origin of cosmic rays. The one square ...kilometer array (KM2A) consisting of 5195 Electromagnetic particle Detectors (ED) and 1188 Muon Detectors (MD) is a sub-array of LHAASO. The EDs are designed to measure the density and arriving time of the secondary particles of extensive air showers. The performance of the EDs is tested for the quality control after construction in the laboratory at sea level. In this paper, the performance of more than four thousands EDs is summarized. The performance of all tested EDs meets the design requirements with the time resolution of 1.6 ns, the detection efficiency of 97.8%, charge resolution for single particle of 18.5% and count rate around 480 Hz. Furthermore, one ED is singled out for monitoring of the long-term stability over a period of nearly two years from December 2018 to November 2020.
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