246 research outputs found
Existence and stability of multiple solutions to the gap equation
We argue by way of examples that, as a nonlinear integral equation, the gap
equation can and does possess many physically distinct solutions for the
dressed-quark propagator. The examples are drawn from a class that is
successful in describing a broad range of hadron physics observables. We apply
the homotopy continuation method to each of our four exemplars and thereby find
all solutions that exist within the interesting domains of light current-quark
masses and interaction strengths; and simultaneously provide an explanation of
the nature and number of the solutions, many of which may be associated with
dynamical chiral symmetry breaking. Introducing a stability criterion based on
the scalar and pseudoscalar susceptibilities we demonstrate, however, that for
any nonzero current-quark mass only the regular Nambu solution of the gap
equation is stable against perturbations. This guarantees that the existence of
multiple solutions to the gap equation cannot complicate the description of
phenomena in hadron physics.Comment: 14 pages, 15 figure
Studies on the soybean aphid, Aphid glycines Matsumura
The soybean aphid is widely distributed among all major soybean growing regions in China. It causes severe damage in Jilin, Liaoning, and Helongjiang Provinces, and part of the inner Mongolian autonomous region, and those areas are often called aphid-stricken areas. Its hosts include wild soybean (Glycine benth forma lanceolate Makino), buckthorn (Rhamnus davuricus) as well as soybean. Results of field investigation and inoculation experiments confirmed that the widely distributed buckthorn in the Northern Provinces is the over-wintering host for soybean aphids. According to the life cycle of aphids and their characteristic damage to soybeans, three different periods of impact can be recognized: 1) starting from seedling stage to blooming stage (mid-July), the aphid population reaches its peak point. About 50-70% of the whole aphid population colonizes on the tender leaves and twigs on top of the soy plants. The soybean damage caused during this period has the worst impact on the plants. 2) During the third ten days of July when the soybean plants cease to grow, aphids then migrate from the top leaves and twigs to the middle or lower ones and feed on the underside of the leaves. At the same time, the young nymphs appear. The aphid population grows slowly, and their damage to soybean plants is at a low tide. 3) From late August -- the late pod bearing period -- to early September -- the yellow maturing period -- aphids start their late multiplying stage. In late Fall, aphids migrate back to buckthorn, their overwintering host, and oviposit overwintering eggs after mating. During Fall, the male aphids and the ovipositional female aphids are living on different hosts. Gynoparae live on buckthorn, and the male aphids live on soybean. Aphids reproduce 15 generations a year on soybean. After analyzing the life cycle of aphids, their growth pattern in the field, as well as the meteorological data in recent years, we came to preliminary results about the growth and decline pattern of aphids and their affecting factors: 1) the more the overwintering eggs and aphids numbers were at the seedling stage, the more severe their impact on seedlings; 2) Average temperatures between 22-25 °C and relative humidity below 78% from late June to early July greatly favored the growth and reproduction of aphids. Even if the original aphid population is small, severe aphid epidemics still could occur during the blooming period in July because aphids reproduced very quickly under those favorable weather conditions; 3) As the growth points ceased growing in late July and the nutrient condition deteriorated, the aphid population declined. In summary, we may make long- or short-term predictions of aphid epidemics based on the number of overwintering eggs, meteorological data, and current and past aphid information. Based on the results of several years’ laboratory and field experiments, the following aphid control measures achieved very good results: 0.5% lindane (benzene hexachloride, or BHC), 1 to 300-400 diluted 6% BHC wettable powder, 1 to 15000 diluted E605 (parathion), 1 to 100 diluted tobacco leaf solution, and seed coating with 20% BHC. Among these methods, 0.5% BHC powder and seed coating with 0.7% of 20% BHC have been widely used in agricultural practice.Originating text in Chinese.Citation: Wang, Cheng Lun, Xiang, Liang Ying, Zhang, Guang Xue, Zhu, Hong Fu. (1962). Studies on the soybean aphid, Aphid glycines Matsumura. Acta Entomologica Sinica, 11, 31-44
SDSS J013127.34032100.1: A newly discovered radio-loud quasar at with extremely high luminosity
Only very few z>5 quasars discovered to date are radio-loud, with a
radio-to-optical flux ratio (radio-loudness parameter) higher than 10. Here we
report the discovery of an optically luminous radio-loud quasar, SDSS
J013127.34-032100.1 (J0131-0321 in short), at z=5.18+-0.01 using the Lijiang
2.4m and Magellan telescopes. J0131-0321 has a spectral energy distribution
consistent with that of radio-loud quasars. With an i-band magnitude of 18.47
and radio flux density of 33 mJy, its radio-loudness parameter is ~100. The
optical and near-infrared spectra taken by Magellan enable us to estimate its
bolometric luminosity to be L_bol ~ 1.1E48 erg/s, approximately 4.5 times
greater than that of the most distant quasar known to date. The black hole mass
of J0131-0321 is estimated to be 2.7E9 solar masses, with an uncertainty up to
0.4 dex. Detailed physical properties of this high-redshift, radio-loud,
potentially super-Eddington quasar can be probed in the future with more
dedicated and intensive follow-up observations using multi-wavelength
facilities.Comment: 5 pages, 3 figures, accepted to ApJ
The 2021 X-ray outburst of magnetar SGR J1935+2154 -- I. Spectral properties
Over a period of multiple active episodes between January 2021 and January
2022, the magnetar SGR J1935+2154 emitted a total of 82 bursts observed by
GECAM-B. Temporal and spectral analyses reveal that the bursts have an average
duration of 145 ms and a fluence ranging from $1.2 \times 10^{-8} \
\mathrm{erg \cdot cm^{-2}}3.7 \times 10^{-5} \ \mathrm{erg \cdot
cm^{-2}}E_{\mathrm{peak}}\alphakT_{\mathrm{min}} \sim 5$ keV of the MBB model, which is
consistent between GECAM-B and GBM-GECAM. This indicates that both samples
originated from similar magnetar bursts. We also reveal the spectra of magnetar
bursts tend to be soft. It indicates that magnetar bursts may be composed of
multiple low BB temperatures and the majority of the BB temperatures are
concentrated around the minimum temperature
Discovery, Semisynthesis, Antiparasitic and Cytotoxic Evaluation of 14-Membered Resorcylic Acid Lactones and Their Derivatives
Ten antifouling 14-membered resorcylic acid lactones 1–10 were isolated previously with low or trace natural abundance from the zoanthid-derived Cochliobolus lunatus fungus. Further optimization of fermentation conditions led to the isolation of two major natural compounds 7 and 8 with multi-gram quantities. By one or two steps, we semisynthesized the six trace natural compounds 1–6 and a series of derivatives 11–27 of compounds 7 and 8 with high yields (65–95%). Compounds 11–13 showed strong antiplasmodial activity against Plasmodium falciparum with IC50 values of 1.84, 8.36, and 6.95μM, respectively. Very importantly, 11 and 12 were non-toxic with very safety and high therapeutic indices (CC50/IC50>180), and thus representing potential promising leads for antiplasmodial drug discovery. Furthermore, 11 was the only compound showed obvious antileishmanial activity against Leishmania donovani with an IC50 value of 9.22μM. Compounds 11 and 12 showed the values of IC50 at 11.9 and 17.2μM against neglected Chagas’ disease causing Trypanosoma cruzi, respectivelyTen antifouling 14-membered resorcylic acid lactones 1–10 were isolated previously with low or trace natural abundance from the zoanthid-derived Cochliobolus lunatus fungus. Further optimization of fermentation conditions led to the isolation of two major natural compounds 7 and 8 with multi-gram quantities. By one or two steps, we semisynthesized the six trace natural compounds 1–6 and a series of derivatives 11–27 of compounds 7 and 8 with high yields (65–95%). Compounds 11–13 showed strong antiplasmodial activity against Plasmodium falciparum with IC50 values of 1.84, 8.36, and 6.95μM, respectively. Very importantly, 11 and 12 were non-toxic with very safety and high therapeutic indices (CC50/IC50>180), and thus representing potential promising leads for antiplasmodial drug discovery. Furthermore, 11 was the only compound showed obvious antileishmanial activity against Leishmania donovani with an IC50 value of 9.22μM. Compounds 11 and 12 showed the values of IC50 at 11.9 and 17.2μM against neglected Chagas’ disease causing Trypanosoma cruzi, respectivel
Discovery, Semisynthesis, Antiparasitic and Cytotoxic Evaluation of 14-Membered Resorcylic Acid Lactones and Their Derivatives
Ten antifouling 14-membered resorcylic acid lactones 1–10 were isolated previously with low or trace natural abundance from the zoanthid-derived Cochliobolus lunatus fungus. Further optimization of fermentation conditions led to the isolation of two major natural compounds 7 and 8 with multi-gram quantities. By one or two steps, we semisynthesized the six trace natural compounds 1–6 and a series of derivatives 11–27 of compounds 7 and 8 with high yields (65–95%). Compounds 11–13 showed strong antiplasmodial activity against Plasmodium falciparum with IC50 values of 1.84, 8.36, and 6.95 μM, respectively. Very importantly, 11 and 12 were non-toxic with very safety and high therapeutic indices (CC50/IC50 > 180), and thus representing potential promising leads for antiplasmodial drug discovery. Furthermore, 11 was the only compound showed obvious antileishmanial activity against Leishmania donovani with an IC50 value of 9.22 μM. Compounds 11 and 12 showed the values of IC50 at 11.9 and 17.2 μM against neglected Chagas’ disease causing Trypanosoma cruzi, respectively.Ten antifouling 14-membered resorcylic acid lactones 1–10 were isolated previously with low or trace natural abundance from the zoanthid-derived Cochliobolus lunatus fungus. Further optimization of fermentation conditions led to the isolation of two major natural compounds 7 and 8 with multi-gram quantities. By one or two steps, we semisynthesized the six trace natural compounds 1–6 and a series of derivatives 11–27 of compounds 7 and 8 with high yields (65–95%). Compounds 11–13 showed strong antiplasmodial activity against Plasmodium falciparum with IC50 values of 1.84, 8.36, and 6.95 μM, respectively. Very importantly, 11 and 12 were non-toxic with very safety and high therapeutic indices (CC50/IC50 > 180), and thus representing potential promising leads for antiplasmodial drug discovery. Furthermore, 11 was the only compound showed obvious antileishmanial activity against Leishmania donovani with an IC50 value of 9.22 μM. Compounds 11 and 12 showed the values of IC50 at 11.9 and 17.2 μM against neglected Chagas’ disease causing Trypanosoma cruzi, respectively
Enhancing the conversational agent with an emotional support system for mental health digital therapeutics
As psychological diseases become more prevalent and are identified as the leading cause of acquired disability, it is essential to assist people in improving their mental health. Digital therapeutics (DTx) has been widely studied to treat psychological diseases with the advantage of cost savings. Among the techniques of DTx, a conversational agent can interact with patients through natural language dialog and has become the most promising one. However, conversational agents' ability to accurately show emotional support (ES) limits their role in DTx solutions, especially in mental health support. One of the main reasons is that the prediction of emotional support systems does not extract effective information from historical dialog data and only depends on the data derived from one single-turn interaction with users. To address this issue, we propose a novel emotional support conversation agent called the STEF agent that generates more supportive responses based on a thorough view of past emotions. The proposed STEF agent consists of the emotional fusion mechanism and strategy tendency encoder. The emotional fusion mechanism focuses on capturing the subtle emotional changes throughout a conversation. The strategy tendency encoder aims at foreseeing strategy evolution through multi-source interactions and extracting latent strategy semantic embedding. Experimental results on the benchmark dataset ESConv demonstrate the effectiveness of the STEF agent compared with competitive baselines
The physical constraints on a new LoBAL QSO at z=4.82
Very few low-ionization broad absorption line (LoBAL) QSOs have been found at
high redshifts to date. One high-redshift LoBAL QSO, J0122+1216, was recently
discovered at the Lijiang 2.4-m Telescope with an initial redshift
determination of 4.76. Aiming to investigate its physical properties, we
carried out follow-up observations in the optical and near-IR spectroscopy.
Near-IR spectra from UKIRT and P200 confirms that it is a LoBAL, with a new
redshift determination of based on the \mgii~ emission-line. The
new \mgii~ redshift determination reveals strong blueshifts and asymmetry of
the high-ionization emission lines. We estimated a black hole mass of and Eddington ratio of according to the
empirical \mgii-based single-epoch relation and bolometric correction factor.
It is possible that strong outflows are the result of an extreme quasar
environment driven by the high Eddington ratio. A lower limit on the outflowing
kinetic power () was derived from both emission and absorption
lines, indicating these outflows play a significant role in the feedback
process to regulate the growth of its black hole as well as host galaxy
evolution.Comment: 12 pages, 10 figures. Accepted for publication in The Astrophysical
Journa
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