In order to investigate the effects of lysine and dissolved oxygen on grass carp, the grass carp were fed with 13, 15 and 17 g kg −1 lysine diet at about 6 mg L−1 (high dissolved oxygen, HO group) or ...3.5 mg L−1 (low dissolved oxygen, LO group) dissolved oxygen level, for 8 weeks. The fish were fed to apparent satiation by hand. The results showed that apparent digestibility of protein, energy and dry matter were decreased significantly when grass carp were fed at 3.5 mg L−1 dissolved oxygen, and feed intake (FI) was also inhibited by low dissolved oxygen (P < 0.05). Weight gain, protein retention, protein efficiency, feed conversion ratio and amino acid retention of fish at 6 mg L−1 dissolved oxygen level were significantly improved at 3.5 mg L−1 dissolved oxygen level (P < 0.05). Weight gain, protein and amino acid retention, and feed efficiency of grass carp at the two dissolved oxygen levels were significantly improved by lysine supplementation (P < 0.05). The dietary lysine level and dissolved oxygen of water had an interaction effect on feed conversion ratios (P < 0.05). Grass carp fed at low dissolved oxygen level showed lower liver protein and fat contents. Plasma aspartate aminotransferase (AST) activity of grass carp fed at 3.5 mg L−1 dissolved oxygen level was significantly increased compared to 6 mg L−1 dissolved oxygen level (P < 0.05). Our results show that low dissolved oxygen level of water is harmful to the liver of grass carp.
We present the improved constraints on couplings of solar axions and more generic bosonic dark matter particles using 737.1 kg days of data from the CDEX-1B experiment. The CDEX-1B experiment, ...located at the China Jinping Underground Laboratory, primarily aims at the direct detection of weakly interacting massive particles using a p-type point-contact germanium detector. We adopt the profile likelihood ratio method for analysis of data in the presence of backgrounds. An energy threshold of 160 eV was achieved, much better than the 475 eV of CDEX-1A with an exposure of 335.6 kg days. This significantly improves the sensitivity for the bosonic dark matter below 0.8 keV among germanium detectors. Limits are also placed on the coupling gAe < 2.48 × 10−11 from Compton, bremsstrahlung, atomic-recombination, and deexcitation channels and geffAN × gAe < 4.14 × 10−17 from a 57Fe M1 transition at 90% confidence level.
The limitation of suitable anomalous valley Hall effect (AVHE) materials has seriously hindered the booming development and the widespread application of valleytronics. Here, through the ...first-principles calculations, we propose a MXene monolayer Y
N
O
with spontaneous valley polarization (VP) of 21.3 meV, which induces intrinsic AVHE. The VP can be modulated linearly, which provides a route of effective control of the valley signals. Importantly, VP can be enhanced by adjusting up the spin-orbit coupling (SOC) based on a SOC Hamiltonian model and the first-principles calculations. From this physics underlying, we substitute the Y atom with the La atom and further propose the monolayer La
N
O
, in which the heavy atom La will provide stronger SOC than Y atom. The spontaneous VP in La
N
O
is enhanced to 100.4 meV, so AVHE can be easily achieved. Our work not only provides compelling candidates for AVHE materials but also offers a novel mindset for finding suitable valleytronic devices.
The precise measurement of the spectrum of protons, the most abundant component of the cosmic radiation, is necessary to understand the source and acceleration of cosmic rays in the Milky Way. This ...work reports the measurement of the cosmic ray proton fluxes with kinetic energies from 40 GeV to 100 TeV, with 2
/
years of data recorded by the DArk Matter Particle Explorer (DAMPE). This is the first time that an experiment directly measures the cosmic ray protons up to ~100 TeV with high statistics. The measured spectrum confirms the spectral hardening at ~300 GeV found by previous experiments and reveals a softening at ~13.6 TeV, with the spectral index changing from ~2.60 to ~2.85. Our result suggests the existence of a new spectral feature of cosmic rays at energies lower than the so-called knee and sheds new light on the origin of Galactic cosmic rays.
We use Monte Carlo analysis to show that explicit representation of an aquifer within a land‐surface model (LSM) decreases the dependence of model performance on accurate selection of subsurface ...hydrologic parameters. Within the National Center for Atmospheric Research Community Land Model (CLM) we evaluate three parameterizations of vertical water flow: (1) a shallow soil profile that is characteristic of standard LSMs; (2) an extended soil profile that allows for greater variation in terrestrial water storage; and (3) a lumped, unconfined aquifer model coupled to the shallow soil profile. North American Land Data Assimilation System meteorological forcing data (1997–2005) drive the models as a single column representing Illinois, USA. The three versions of CLM are each run 22,500 times using a random sample of the parameter space for soil texture and key hydrologic parameters. Other parameters remain constant. Observation‐based monthly changes in state‐averaged terrestrial water storage (dTWS) are used to evaluate the model simulations. After single‐criteria parameter exploration, the schemes are equivalently adept at simulating dTWS. However, explicit representation of groundwater considerably decreases the sensitivity of modeled dTWS to errant parameter choices. We show that approximate knowledge of parameter values is not sufficient to guarantee realistic model performance: because interaction among parameters is significant, they must be prescribed as a congruent set.
ABSTRACT
We present timing solutions and analyses of 11 pulsars discovered by the Five-hundred-meter Aperture Spherical radio Telescope (FAST). These pulsars were discovered using an ultrawide ...bandwidth receiver in drift-scan observations made during the commissioning phase of FAST, and were then confirmed and timed using the 64-m Parkes Radio Telescope. Each pulsar has been observed over a span of at least one year. Highlighted discoveries include PSR J0344−0901, which displays mode-changing behaviour and may belong to the class of so-called swooshing pulsars (alongside PSRs B0919+06 and B1859+07); PSR J0803−0942, whose emission is almost completely linearly polarized; and PSRs J1900−0134 and J1945+1211, whose well-defined polarization angle curves place stringent constraints on their emission geometry. We further discuss the detectability of these pulsars by earlier surveys, and highlight lessons learned from our work in carrying out confirmation and monitoring observations of pulsars discovered by a highly sensitive telescope, many of which may be applicable to next-generation pulsar surveys. This paper marks one of the first major releases of FAST-discovered pulsars, and paves the way for future discoveries anticipated from the Commensal Radio Astronomy FAST Survey.
The impact of heterogeneous uptake of HO2 on aerosol surfaces on radical concentrations and the O3 production regime in Beijing in summertime was investigated. The uptake coefficient of HO2 onto ...aerosol surfaces, γHO2, was calculated for the AIRPRO campaign in Beijing, in summer 2017, as a function of measured aerosol soluble copper concentration, Cu2+eff, aerosol liquid water content, ALWC, and particulate matter concentration, PM. An average γHO2 across the entire campaign of 0.070±0.035 was calculated, with values ranging from 0.002 to 0.15, and found to be significantly lower than the value of γHO2=0.2, commonly used in modelling studies. Using the calculated γHO2 values for the summer AIRPRO campaign, OH, HO2 and RO2 radical concentrations were modelled using a box model incorporating the Master Chemical Mechanism (v3.3.1), with and without the addition of γHO2, and compared to the measured radical concentrations. The rate of destruction analysis showed the dominant HO2 loss pathway to be HO2 + NO for all NO concentrations across the summer Beijing campaign, with HO2 uptake contributing <0.3 % to the total loss of HO2 on average. This result for Beijing summertime would suggest that under most conditions encountered, HO2 uptake onto aerosol surfaces is not important to consider when investigating increasing O3 production with decreasing PM across the North China Plain. At low NO, however, i.e. <0.1 ppb, which was often encountered in the afternoons, up to 29 % of modelled HO2 loss was due to HO2 uptake on aerosols when calculated γHO2 was included, even with the much lowerγHO2 values compared to γHO2= 0.2, a result which agrees with the aerosol-inhibited O3 regime recently proposed by Ivatt et al. (2022). As such it can be concluded that in cleaner environments, away from polluted urban centres where HO2 loss chemistry is not dominated by NO but where aerosol surface area is high still, changes in PM concentration and hence aerosol surface area could still have a significant effect on both overall HO2 concentration and the O3 production regime.Using modelled radical concentrations, the absolute O3 sensitivity to NOx and volatile organic compounds (VOCs) showed that, on average across the summer AIRPRO campaign, the O3 production regime remained VOC-limited, with the exception of a few days in the afternoon when the NO mixing ratio dropped low enough for the O3 regime to shift towards being NOx-limited. The O3 sensitivity to VOCs, the dominant regime during the summer AIRPRO campaign, was observed to decrease and shift towards a NOx-sensitive regime both when NO mixing ratio decreased and with the addition of aerosol uptake. This suggests that if NOx continues to decrease in the future, ozone reduction policies focussing solely on NOx reductions may not be as efficient as expected if PM and, hence, HO2 uptake to aerosol surfaces continue to decrease. The addition of aerosol uptake into the model, for both the γHO2 calculated from measured data and when using a fixed value of γHO2=0.2, did not have a significant effect on the overall O3 production regime across the campaign. While not important for this campaign, aerosol uptake could be important for areas of lower NO concentration that are already in a NOx-sensitive regime.
A
bstract
The Born cross sections of the
e
+
e
−
→ D
*+
D
*
−
and
e
+
e
−
→ D
*+
D
−
processes are measured using
e
+
e
−
collision data collected with the BESIII experiment at center-of-mass ...energies from 4.085 to 4.600 GeV, corresponding to an integrated luminosity of 15
.
7 fb
−
1
. The results are consistent with and more precise than the previous measurements by the Belle, Babar and CLEO collaborations. The measurements are essential for understanding the nature of vector charmonium and charmonium-like states.
Bacterial-fungal interactions influence microbial community performance of most ecosystems and elicit specific microbial behaviours, including stimulating specialised metabolite production. Here, we ...use a co-culture experimental evolution approach to investigate bacterial adaptation to the presence of a fungus, using a simple model of bacterial-fungal interactions encompassing the bacterium Bacillus subtilis and the fungus Aspergillus niger. We find in one evolving population that B. subtilis was selected for enhanced production of the lipopeptide surfactin and accelerated surface spreading ability, leading to inhibition of fungal expansion and acidification of the environment. These phenotypes were explained by specific mutations in the DegS-DegU two-component system. In the presence of surfactin, fungal hyphae exhibited bulging cells with delocalised secretory vesicles possibly provoking an RlmA-dependent cell wall stress. Thus, our results indicate that the presence of the fungus selects for increased surfactin production, which inhibits fungal growth and facilitates the competitive success of the bacterium.
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