55,226 research outputs found
An analytical demonstration of coupling schemes between magnetohydrodynamic codes and eddy current codes
No full textIn order to model a magnetohydrodynamic (MHD) instability that strongly couples to external conducting structures (walls and/or coils) in a fusion device, it is often necessary to combine a MHD code solving for the plasma response, with an eddy current code computing the fields and currents of conductors. We present a rigorous proof of the coupling schemes between these two types of codes. One of the coupling schemes has been introduced and implemented in the CARMA code {[}R. Albanese, Y. Q. Liu, A. Portone, G. Rubinacci, and F. Villone, IEEE Trans. Magn. 44, 1654 (2008); A. Portone, F. Villone, Y. Q. Liu, R. Albanese, and G. Rubinacci, Plasma Phys. Controlled Fusion 50, 085004 (2008)] that couples the MHD code MARS-F {[}Y. Q. Liu, A. Bondeson, C. M. Fransson, B. Lennartson, and C. Breitholtz, Phys. Plasmas 7, 3681 (2000)] and the eddy current code CARIDDI {[}R. Albanese and G. Rubinacci, Adv. Imaging Electron Phys. 102, 1 (1998)]. While the coupling schemes are described for a general toroidal geometry, we give the analytical proof for a cylindrical plasma
Finite linear spaces admitting a projective group PSU(3,q) with q even
No full textAbstractThis article is a contribution to the study of the automorphism groups of finite linear spaces. In particular we look at simple groups and prove the following theorem:Let G=PSU(3,q) with q even and G acts line-transitively on a finite linear space S. Then S is one of the following cases:(i)A projective plane;(ii)A regular linear space with parameters (b,v,r,k)=(q2(q2−q+1),q3+1,q2−q+1,q+1). This is called the Hermitian unitary design
q-Differential equations for q-classical polynomials and q-Jacobi-Stirling numbers
No full textWe introduce, characterise and provide a combinatorial interpretation for the so-called q-Jacobi–Stirling numbers.
This study is motivated by their key role in the (reciprocal) expansion of any power of a second order
q-differential operator having the q-classical polynomials as eigenfunctions in terms of other even order operators,
which we explicitly construct in this work. The results here obtained can be viewed as the q-version of
those given by Everitt et al. and by the first author, whilst the combinatorics of this new set of numbers is a
q-version of the Jacobi–Stirling numbers given by Gelineau and the second author
INNOVATIVE PILLAR[6]ARENE-BASED STATIONARY PHASES FOR HIGH-RESOLUTION GAS CHROMATOGRAPHIC ANALYSES
No full textIn this work, the synthesis, fabrication, and characterization of new stationary phases based on pillar[6]arene derivative modified by long alkyl chains (P6A-C10) for high-resolution gas chromatographic (GC) analyses are reported. Pillar[n]arenes are a new class of macrocyclic hosts that can accommodate specific guests due to their highly symmetrical and rigid pillar architectures with π-electron rich cavities. Quantum chemistry calculations have been performed, showing a difference in non-covalent interactions with the P6A-C10 pillar framework, which leads to specific selectivity for aromatic compounds. The GC columns prepared with these innovative stationary phases exhibited a medium polarity, and good reproducibility for run-to-run, day-to-day, and column-to-column analyses [1], demonstrating great potential as new stationary phases in separation science. Furthermore, peculiar advantages are achieved if compared with the commercial HP-5, HP-35, DB-17, and PEG-20M columns, showing unmatched resolving capabilities toward chloroaniline, bromoaniline, iodoaniline, toluidine, and xylene isomers [2].
References:
1. Sun, T., Chen, R., Huang, Q., Ba, M., Cai, Z., Hu, S., Liu, X., Nardiello, D., & Quinto, M., ACS Appl. Mater. Interfaces 14 (2022) 56132−56142.
2. Sun, T., Chen, R., Huang, Q., Ba, M., Cai, Z., Chen, H., Qi, Y., Chen, H., Liu, X., Nardiello, D., & Quinto, M., Anal. Chim. Acta 1251 (2023) 340979
Are Chinese loess deposits essentially continuous?
No full textWe conducted a paleomagnetic examination of the last glacial loess of three representative profiles along an east-west transect in the central Loess Plateau in order to assess the continuity of Chinese loess. The results show that the Xifeng and Luochuan profiles record the Laschamp geomagnetic excursion but with different morphologies. Together with the published results from Weinan, southern plateau, our results suggest that sedimentation of the last glacial loess in the central-southern plateau was continuous at the time scale equivalent to the duration of the Laschamp excursion (~2 kyr), but probably episodic at finer time scales (<2 kyr). No geomagnetic excursion was found at the Yichuan profile near the Yellow River valley, where loess accumulation may be strongly affected by local environmental changes and thus may have been discontinuous. Both site location and time scale therefore need to be considered when considering continuity of Chinese loess.<br/
Ophiorrhiza pseudonapoensis L. Wu & Q. R. Liu 2023, sp. nov.
No full textOphiorrhiza pseudonapoensis L. Wu & Q. R. Liu, sp. nov. (Figs. 1–3) Type:— China. Yunnan: Hekou county, Nanxi town, alt. 950 m, Ẵễ (Lei Wu) 4225 (holotype, CSFI076284!; isotypes, BNU!, CSFI076278!, CSFI076285!, CSFI076286!, CSFI076287!). Diagnosis:— Ophiorrhiza pseudonapoensis is similar to O. napoensis, but the former differs from the latter in having 5–10 (vs ca. 1) mm long stipules, persistent (vs caducous) bracts, oblanceolate (vs lanceolate-linear) bracts, homostylous (vs heterostylous) flowers, and ensiform (vs narrowly triangular) calyx lobes. The new species also resembles O. macrocarpa L. Wu & Q. R. Liu (2018: 2), but it can be distinguished from the latter by its 5–10 (vs less than 1) mm long stipules, oblanceolate (vs subulate or linear subulate) and 7–20 (vs less than 5) mm long bracts, and (1.2–)1.5–2(–2.5) (vs 0.4–0.6) mm long calyx lobes. Description:— Erect or suberect herbs, 25–35 cm tall; stem glabrous, often dark purplish when dry. Leaves usually in unequal pairs; petiole shorter than 1 cm, blade drying papery, dark greenish adaxially, greenish-yellow abaxially, lanceolate, oblanceolate, or ovate-lanceolate, 7–17(–21) × 2–4 cm, base cuneate, margin entire, apex acuminate, glabrous on both surfaces; secondary veins 9–12 on each side, both sides flat, clearly visible abaxially; stipules narrowly triangular, 5–10 mm long, apex acuminate, persistent. Inflorescences congested-cymose, terminal, erect, usually many flowered; peduncles 1–4 cm long; axes 0.3–2.5 cm long, helicoid, puberulent or subglabrous; bracts oblanceolate, 7–20 mm long, apex obtuse, glabrous. Flowers homostylous on 1–2 mm long pedicels. Calyx puberulent; lobes 5, ensiform, (1.2–)1.5–2(–2.5) mm long, with one gland at each sinus; hypanthium 1.2–1.5 × 2–2.5 mm, inconspicuously 5-ribbed. Corolla pale pink or white, drying yellow-brown, salverform, glabrous outside; tube 25–28 mm long, glabrous inside except puberulent at the throat; lobes 5, subovate, 4–5 × 3.5–4 mm, dorsally smooth, rostrate at apex. Stamens 5, attached to the throat of the corolla tube; anthers linear-oblong, ca. 2.0 mm long; filaments 1.5–2.2 mm long, glabrous; stigmas 0.5 mm long, sub-capitate, shallowly bilobed, reaching a little higher than anthers. Capsules mitriform or obcordate, ca. 3 × 9 mm. Seeds many, angular. Phenology:— Flowering from October to January of next year. Etymology:— The specific epithet is derived from its morphology that is closely resembling Ophiorrhiza napoensis. Distribution and Habitat:— Ophiorrhiza pseudonapoensis is only known from southeastern Yunnan until now. All individuals observed in the wild are distributed in limestone areas and grow in humid places, such as along stream banks, or sometimes on wet cliff under dense forest cover at altitudes of 500–1500 m. Conservation status:— So far, only two Ophiorrhiza pseudonapoensis populations in Maguan and Hekou with more than 1000 mature individuals were observed during our investigations. And the population we discovered from Maguan is in the Gulinjing provincial nature reserve, where habitats are in good condition and there are no threatening factors until now. According to the type specimens, we speculate that there are more than ten populations with more than 2000 mature individuals in total from southeastern Yunnan, and the distribution area is more than 30 km 2. Thus, this species is assigned a status of Least Concern (LC) following the guidelines of IUCN (2022). Additional specimens examined (paratypes):— CHINA. Yunnan: Maguan, X.T. Cai 51898 (IBSC), Y.J. Hu GS86-2101 (IBSC), Chen & Li 86SL-343 (IBSC, YSY), 86SL-7946 (IBSC, YSY), GL86-2051 (IBSC, YSY), GL86- 7558 (IBSC, YSY), GL86-7864 (IBSC, YSY), Y.M. Shui et al. 30216 (PE), 31119 (IBSC, PE), L. Wu. 4232 (BNU, CSFI); Xichou, A.Q. Wu 7761 (KUN), 7899 (KUN), without locality, Z.L. Lin 14031304 (KUN). Notes:— Flowers of Ophiorrhiza napoensis were described by Lo (1990) as “corolla tube 2–2.2 mm long, stamens inserted at the throat of corolla tube, stylus 1.3–1.4 cm long, stigma 2.5–3 mm long, 2-lobed”, and its biology was noted as “it might be homostylous” in the protologue. Through a careful observation of floral trait correlations, Kudoh et al. (2001) indicated that O. napoensis has both long- and short-styled morphs, viz. stigmas positioned at the throat while anthers located a little above the middle of the corolla tube in the long-styled form, and opposite in the short-styled form. However, in recent work, Tao & Taylor (2011) followed the description of Lo (1990) instead of Kudoh et al. (2001) and noted that the floral biology of this species as unknown. After several field investigations in Guangxi and Yunnan, southwestern China, we support the conclusion of Kudoh et al. (2001) that the flowers of O. napoensis are heterostylous (Fig. 4, C–I), and confirm the O. pseudonapoensis is a misidentification of O. napoensis. Ophiorrhiza pseudonapoensis is also similar to O. macrocarpa based on flower form and corolla shape but differs in having longer stipules (5–10 mm) (vs less than 1 mm in O. macrocarpa), longer bracts (7–20 mm long) (vs less than 5 mm), oblanceolate bracts (vs subulate or linear subulate), and much longer calyx lobes (1.2–2.5 mm long) (vs 0.4–0.6 mm long) (Fig. 4, A–C). More detailed comparisons among the three species are listed in Table 1.Published as part of Liu, Qin, Chen, Ao-Xue, Liao, Xiao-Wen, Liu, Quan-Ru & Wu, Lei, 2023, Ophiorrhiza pseudonapoensis (Rubiaceae), a new species from Yunnan, southwestern China, pp. 228-234 in Phytotaxa 607 (4) on pages 229-233, DOI: 10.11646/phytotaxa.607.4.1, http://zenodo.org/record/824332
"Closing the R&D Gap, Evaluating the Sources of R&D Spending"
No full textBoth spending and tax policies have been implemented in the United States with the goal of stimulating private sector research and development (R&D). Karier questions whether current R&D policy, especially the research and experimentation tax credit, can contribute to closing the gap between nondefense expenditures on R&D in the United States and such expenditures in other countries, such as Japan and Germany. He also explores possible changes to our current R&D policy to make it more effective.
Cancellation of drift kinetic effects between thermal and energetic particles on the resistive wall mode stabilization
No full textDrift kinetic stabilization of the resistive wall mode (RWM) is computationally investigated using MHD-kinetic hybrid code MARS-K following the non-perturbative approach (Liu et al 2008 Phys. Plasmas 15 112503), for both reversed field pinch (RFP) and tokamak plasmas. Toroidal precessional drift resonance effects from trapped energetic ions (EIs) and various kinetic resonances between the mode and the guiding center drift motions of thermal particles are included into the self-consistent toroidal computations. The results show cancellation effects of the drift kinetic damping on the RWM between the thermal particles and EIs contributions, in both RFP and tokamak plasmas, even though each species alone can provide damping and stabilize RWM instability by respective kinetic resonances. The degree of cancellation generally depends on the EIs equilibrium distribution, the particle birth energy, as well as the toroidal flow speed of the plasma
Exotic tetraquark states with the qq (Q)over-bar(Q)over-bar configuration
No full textIn this work, we study systematically the mass splittings of the qq (Q) over bar(Q) over bar (q = u, d, s and Q = c, b) tetraquark states with the color-magnetic interaction by considering color mixing effects and estimate roughly their masses. We find that the color mixing effect is relatively important for the J(P) = 0(+) states and possible stable tetraquarks exist in the nn (Q) over bar(Q) over bar (n = u, d) and ns (Q) over bar(Q) over bar systems either with J = 0 or with J = 1. Possible decay patterns of the tetraquarks are briefly discussed.National Natural Science Foundation of China [11175073, 11275115, 11222547, 11261130311]; 973 program; National Program for Support of Top-notch Young Professionals; Fundamental Research Funds for the Central UniversitiesSCI(E)ARTICLE107
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