27,839 research outputs found
Alfvenic Ion Temperature Gradient Activities in a Weak Magnetic Shear Plasma
We report the first experimental evidence of Alfvenic ion temperature
gradient (AITG) modes in HL-2A Ohmic plasmas. A group of oscillations with
kHz and is detected by various diagnostics in high-density
Ohmic regimes. They appear in the plasmas with peaked density profiles and weak
magnetic shear, which indicates that corresponding instabilities are excited by
pressure gradients. The time trace of the fluctuation spectrogram can be either
a frequency staircase, with different modes excited at different times or
multiple modes may simultaneously coexist. Theoretical analyses by the extended
generalized fishbone-like dispersion relation (GFLDR-E) reveal that mode
frequencies scale with ion diamagnetic drift frequency and , and they
lie in KBM-AITG-BAE frequency ranges. AITG modes are most unstable when the
magnetic shear is small in low pressure gradient regions. Numerical solutions
of the AITG/KBM equation also illuminate why AITG modes can be unstable for
weak shear and low pressure gradients. It is worth emphasizing that these
instabilities may be linked to the internal transport barrier (ITB) and H-mode
pedestal physics for weak magnetic shear.Comment: 9 pages, 7 figure
Ultrasonographic findings in cows with left displacement of abomasum, before and after reposition surgery
Background: The natural incidence of left displacement of abomasum (LDA) in dairy cows was high. The diagnosis of LDA usually relies on characteristic physical exam findings but that transabdominal ultrasound is a useful technique that has been applied to the diagnosis of gastrointestinal diseases of dairy cows in equivocal cases. Methods: Forty dairy cows with LDA were clinically and ultrasonographically examined to determine the position and the echogenic property of the abomasum. The cows were examined ultrasonographically on the left side, from the 9th intercostal space (ICS) to the 12th ICS as well as the ventral left abdomen before and after reposition surgery. Results: The vital signs were within normal range in most of the cows and the âpingingâ were clearly heard in 37 cows. The abomasal gas cap was visualized from the 9th to 12th ICS in 37 cows and characterized by reverberation artifacts. The abomasal ingesta appeared as homogeneous hypoechoic fluid with scattered hyperechoic foci and were mainly visible in the median region and ventral region of the 9th to 11th ICS in 35 cows. The pyloric canal was detected from the ventral left abdomen wall in 30 cows and appeared as a loop with hypoechogenic wall and echogenic luminal contents in cross section. Conclusion: These typical ultrasonograms, including reverberation artifacts, homogenous hypoechoic structures, are important diagnostic feature in ultrasonography of LDA. Furthermore, the circular acoustic image structure of the pyloric canal is an important characteristic of LDA, so it can be used as an important diagnostic basis of LDA
An integrated assessment of INDCs under Shared Socioeconomic Pathways: an implementation of C(3)IAM
A series of global actions have been made to address climate change. As a recent developed climate policy, Intended Nationally Determined Contributions (INDC) have renewed attention to the importance of exploring temperature rise levels lower than 2 °C, in particular a long-term limit of 1.5 °C, compared to the preindustrial level. Nonetheless, achieving the 2 °C target under the current INDCs depends on dynamic socioeconomic development pathways. Therefore, this study conducts an integrated assessment of INDCs by taking into account different Shared Socioeconomic Pathways (SSPs). To that end, the CEEP-BIT research community develops the Chinaâs Climate Change Integrated Assessment Model (C3IAM) to assess the climate change under SSPs in the context of with and without INDCs. Three SSPs, including âa green growth strategyâ (SSP1), âa more middle-of-the-road development patternâ (SSP2) and âfurther fragmentation between regionsâ (SSP3) form the focus of this study. Results show that after considering INDCs, mitigation costs become very low and they have no evident positive changes in three SSPs. In 2100, a temperature rise would occur in SSP1-3, which is 3.20, 3.48 and 3.59 °C, respectively. There are long-term difficulties to keep warming well below 2 °C and pursue efforts toward 1.5 °C target even under INDCs. A drastic reduction in greenhouse gas emissions is needed in order to mitigate potentially catastrophic climate change impacts. This work contributes on realizing the hard link between the earth and socioeconomic systems, as well as extending the economic models by coupling the global CGE model with the economic optimum growth model. In C3IAM, Chinaâs energy consumption and emissions pattern are investigated and refined. This study can provide policy makers and the public a better understanding about pathways through which different scenarios could unfold toward 2100, highlights the real mitigation and adaption challenges faced by climate change and can lead to formulating effective policies
Knowledge, attitudes and practices relating to influenza A(H7N9) risk among live poultry traders in Guangzhou City, China
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The DArk Matter Particle Explorer mission
The DArk Matter Particle Explorer (DAMPE), one of the four scientific space
science missions within the framework of the Strategic Pioneer Program on Space
Science of the Chinese Academy of Sciences, is a general purpose high energy
cosmic-ray and gamma-ray observatory, which was successfully launched on
December 17th, 2015 from the Jiuquan Satellite Launch Center. The DAMPE
scientific objectives include the study of galactic cosmic rays up to
TeV and hundreds of TeV for electrons/gammas and nuclei respectively, and the
search for dark matter signatures in their spectra. In this paper we illustrate
the layout of the DAMPE instrument, and discuss the results of beam tests and
calibrations performed on ground. Finally we present the expected performance
in space and give an overview of the mission key scientific goals.Comment: 45 pages, including 29 figures and 6 tables. Published in Astropart.
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Search for psi(3770)\ra\rho\pi at the BESII detector at the Beijing Electron-Positron Collider
Non- decay \psppto \rhopi is searched for using a data sample of
taken at the center-of-mass energy of 3.773 GeV by the
BESII detector at the BEPC. No \rhopi signal is observed, and the upper limit
of the cross section is measured to be \sigma(\EETO \rhopi)<6.0 pb at 90% C.
L. Considering the interference between the continuum amplitude and the \pspp
resonance amplitude, the branching fraction of \pspp decays to is
determined to be \BR(\pspp\ra\rho\pi)\in(6.0\times10^{-6}, 2.4\times10^{-3})
at 90% C. L. This is in agreement with the prediction of the - and -wave
mixing scheme of the charmonium states for solving the ``\rhopi puzzle''
between \jpsi and \psp decays.Comment: 15 pages, 5 figure
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