Effects of phosphorus availability and phosphorus utilization behavior of Microcystis aeruginosa on its adaptation capability to ultraviolet radiation

M. aeruginosa has strong adaptation capability in the eutrophic UV-radiated waters and P enrichment could alleviate the negative effects of UV radiation. © 2019Phosphorus (P) plays a critical role in eutrophication and algal growth; therefore, improving our understanding of the impact of P is essential to control harmful algal blooms. In this study, Microcystis aeruginosa was treated with 5-h ambient irradiation in the medium with different dissolved inorganic P (DIP) concentrations, DIP-free, moderate-DIP, and high-DIP, to explore its growth and other physiological responses. Compared to photosynthetically active radiation (PAR), UV-A (320–400 nm) and UV-B (280–320 nm) radiation had inhibitive effects on the photosynthesis and growth of M. aeruginosa, while high P availability could alleviate or eliminate the negative effects of UV radiation. The photosynthetic parameters had a minimum reduction and quickly recovered after re-inoculation under high-DIP conditions. Confirmed by SEM, photosynthetic pigments, the generation of reactive oxygen species (ROS), superoxide dismutase (SOD) activity and other methods, ambient UV radiation exerted oxidative stresses rather than direct lethal effects on M. aeruginosa. Photosynthetic parameters indicated that algal UV-adaptation processes could include decreasing photo-induced damages and increasing self-repair efficiency. The P acquired by M. aeruginosa cells can have two function, which included alleviating UV-induced negative effects and sustaining algal growth. Consequently, UV-adaptation processes of M. aeruginosa resulted in an elevated demand for DIP, which resulted to increased P uptake rates and cellular P quota under moderate and high-DIP conditions. Therefore, the production of carotenoid and phycocyanin, and SOD activity increased under UV stress, leading to a better adaptation capability of M. aeruginosa and decreased negative effects of UV radiation on its growth. Overall, our findings demonstrated the significant interactive effects of P enrichment and irradiation on typical cyanobacteria, and the strong adaptation capability of M. aeruginosa in the eutrophic UV-radiated waters

Doping-insensitive density-of-states suppression in polycrystalline iron-based superconductor SmO1−x_{1-x}Fx_{x}FeAs

We investigated the temperature dependence of the density-of-states in the iron-based superconductor SmO_1-xF_xFeAs (x=0, 0.12, 0.15, 0.2) with high resolution angle-integrated photoemission spectroscopy. The density-of-states suppression is observed with decreasing temperature in all samples, revealing two characteristic energy scales (10meV and 80meV). However, no obvious doping dependence is observed. We argue that the 10meV suppression is due to an anomalously doping-independent normal state pseudogap, which becomes the superconducting gap once in the superconducting state; and alert the possibility that the 80meV-scale suppression might be an artifact of the polycrystalline samples.Comment: 4 pages, 4 figure

The energy spectrum of all-particle cosmic rays around the knee region observed with the Tibet-III air-shower array

We have already reported the first result on the all-particle spectrum around the knee region based on data from 2000 November to 2001 October observed by the Tibet-III air-shower array. In this paper, we present an updated result using data set collected in the period from 2000 November through 2004 October in a wide range over 3 decades between $10^{14}$ eV and $10^{17}$ eV, in which the position of the knee is clearly seen at around 4 PeV. The spectral index is -2.68 $\pm$ 0.02(stat.) below 1PeV, while it is -3.12 $\pm$ 0.01(stat.) above 4 PeV in the case of QGSJET+HD model, and various systematic errors are under study now.Comment: 12 pages, 7 figures, accepted by Advances in space researc

Moon Shadow by Cosmic Rays under the Influence of Geomagnetic Field and Search for Antiprotons at Multi-TeV Energies

We have observed the shadowing of galactic cosmic ray flux in the direction of the moon, the so-called moon shadow, using the Tibet-III air shower array operating at Yangbajing (4300 m a.s.l.) in Tibet since 1999. Almost all cosmic rays are positively charged; for that reason, they are bent by the geomagnetic field, thereby shifting the moon shadow westward. The cosmic rays will also produce an additional shadow in the eastward direction of the moon if cosmic rays contain negatively charged particles, such as antiprotons, with some fraction. We selected 1.5 x10^{10} air shower events with energy beyond about 3 TeV from the dataset observed by the Tibet-III air shower array and detected the moon shadow at $\sim 40 \sigma$ level. The center of the moon was detected in the direction away from the apparent center of the moon by 0.23$^\circ$ to the west. Based on these data and a full Monte Carlo simulation, we searched for the existence of the shadow produced by antiprotons at the multi-TeV energy region. No evidence of the existence of antiprotons was found in this energy region. We obtained the 90% confidence level upper limit of the flux ratio of antiprotons to protons as 7% at multi-TeV energies.Comment: 13pages,4figures; Accepted for publication in Astroparticle Physic

Analytical studies of Hawking radiation and quasinormal modes in rotating linear dilatonic black hole

The rotating linear dilatonic black hole is an asymptotically non-flat solution to Einstein-Maxwell-Dilaton-Axion gravity theory due to the existence of non-trivial matter fields. We have analytically studied the wave equation of scalar field in this background and shown that the radial wave equation can be solved in terms of hypergeometric function. By determining the ingoing and the outgoing fluxes at the asymptotic infinity, we have found the analytical expressions for reflection coefficient and greybody factor for certain scalar modes. In the high frequency regime, we obtain the Hawking temperature by comparing the blackbody spectrum with the radiation spectrum resulting from reflection coefficient. It is shown that the Hawking temperature, which depends only on the linear dilatonic background parameter, does not agree with the temperature calculated from surface gravity. At last, the quasinormal modes of scalar field perturbation are presented, which shows that the rotating linear dilationic black hole is unstable for certain modes apart from the superradiant modes.Comment: 7 pages, 2 figures Comments are welcom

Accurate Diagnosis of Colorectal Cancer Based On Histopathology Images Using Artificial Intelligence

Background: Accurate and robust pathological image analysis for colorectal cancer (CRC) diagnosis is time-consuming and knowledge-intensive, but is essential for CRC patients’ treatment. The current heavy workload of pathologists in clinics/hospitals may easily lead to unconscious misdiagnosis of CRC based on daily image analyses. Methods: Based on a state-of-the-art transfer-learned deep convolutional neural network in artificial intelligence (AI), we proposed a novel patch aggregation strategy for clinic CRC diagnosis using weakly labeled pathological whole-slide image (WSI) patches. This approach was trained and validated using an unprecedented and enormously large number of 170,099 patches, \u3e 14,680 WSIs, from \u3e 9631 subjects that covered diverse and representative clinical cases from multi-independent-sources across China, the USA, and Germany. Results: Our innovative AI tool consistently and nearly perfectly agreed with (average Kappa statistic 0.896) and even often better than most of the experienced expert pathologists when tested in diagnosing CRC WSIs from multicenters. The average area under the receiver operating characteristics curve (AUC) of AI was greater than that of the pathologists (0.988 vs 0.970) and achieved the best performance among the application of other AI methods to CRC diagnosis. Our AI-generated heatmap highlights the image regions of cancer tissue/cells. Conclusions: This first-ever generalizable AI system can handle large amounts of WSIs consistently and robustly without potential bias due to fatigue commonly experienced by clinical pathologists. It will drastically alleviate the heavy clinical burden of daily pathology diagnosis and improve the treatment for CRC patients. This tool is generalizable to other cancer diagnosis based on image recognition

Charge Asymmetries for D, D_s and Lambda_c Production in Sigma- - Nucleus Interactions at 340 GeV/c

CERN experiment WA89 has studied charmed particles produced by a Sigma^- beam at 340 GeV/c on nuclear targets. Production of particles which have light quarks in common with the beam is compared to production of those which do not. Considerable production asymmetries between D^- and D^p, D_s^ and D_s^+ and Lambda_c and Antilambda_c are observed. The results are compared with pion beam data and with theoretical calculations.Comment: LaTeX ; 16 pages including 4 ps figure

Have Superheavy Elements been Produced in Nature?

We discuss the possibility whether superheavy elements can be produced in Nature by the astrophysical rapid neutron capture process. To this end we have performed fully dynamical network r-process calculations assuming an environment with neutron-to-seed ratio large enough to produce superheavy nuclei. Our calculations include two sets of nuclear masses and fission barriers and include all possible fission channels and the associated fission yield distributions. Our calculations produce superheavy nuclei with A ~ 300 that however decay on timescales of days.Comment: 12 pages, 11 figure

Are protons still dominant at the knee of the cosmic-ray energy spectrum?

A hybrid experiment consisting of emulsion chambers, burst detectors and the Tibet II air-shower array was carried out at Yangbajing (4,300 m a.s.l., 606 g/cm$^2$) in Tibet to obtain the energy spectra of primary protons and heliums. From three-year operation, these energy spectra are deduced between $10^{15}$ and $10^{16}$ eV by triggering the air showers associated with a high energy core and using a neural network method in the primary mass separation. The proton spectrum can be expressed by a single power-law function with a differential index of $-3.01 \pm 0.11$ and $-3.05 \pm 0.12$ based on the QGSJET+HD and SIBYLL+HD models, respectively, which are steeper than that extrapolated from the direct observations of $-2.74 \pm 0.01$ in the energy range below $10^{14}$ eV. The absolute fluxes of protons and heliums are derived within 30% systematic errors depending on the hadronic interaction models used in Monte Carlo simulation. The result of our experiment suggests that the main component responsible for the change of the power index of the all-particle spectrum around $3 \times 10^{15}$ eV, so-called ``knee'', is composed of nuclei heavier than helium. This is the first measurement of the differential energy spectra of primary protons and heliums by selecting them event by event at the knee energy region.Comment: This paper has been accepted for publication Physics Letters B on October 19th, 2005. This paper has been accepted for publication Physics Letters B on October 19th, 200