53,214 research outputs found
Multiple solutions for the non-Abelian Chern–Simons–Higgs vortex equations
No full textIn this paper we study the existence of multiple solutions for the non-Abelian Chem-Simons-Higgs (N x N)-system:Delta u(i) = lambda(Sigma(N)(j=1) Sigma(N)(k=1) K(kj)K(ji)e(uj)e(uk) - Sigma(N)(j=1) k(ji)e(uj)) + 4 pi Sigma(ni)(j=1) delta(pij), i=1, . . . , N;over a doubly periodic domain Omega, with coupling matrix K given by the Cartan matrix of SU(N + 1), (see (1.2) below). Here, lambda > 0 is the coupling parameter, delta(p )is the Dirac measure with pole at p and n(i) is an element of N, for i = 1,...,N. When N = 1, 2 many results are now available for the periodic solvability of such system and provide the existence of different classes of solutions known as: topological, non-topological, mixed and blow-up type. On the contrary for N >= 3, only recently in [27] the authors managed to obtain the existence of one doubly periodic solution via a minimization procedure, in the spirit of [46]. Our main contribution in this paper is to show (as in [46]) that actually the given system admits a second doubly periodic solutions of "Mountain-pass" type, provided that 3 <= N <= 5. Note that the existence of multiple solutions is relevant from the physical point of view. Indeed, it implies the co-existence of different non-Abelian Chem-Simons condensates sharing the same set (assigned component-wise) of vortex points, energy and fluxes. The main difficulty to overcome is to attain a "compactness" property encompassed by the so-called Palais-Smale condition for the corresponding "action" functional, whose validity remains still open for N >= 6. (C) 2019 Elsevier Masson SAS. All rights reserved
Letter from X. N. Steeves to Carl Hayden
No full textLetter from X. N. Steeves to Carl T. Hayden describing road conditions around the Grand Canyon National Par
Letter from Carl Hayden to X. N. Steeves
No full textLetter with red pencil corrections from Carl T. Hayden to X. N. Steeves about the construction of an approach road to the canyo
A 2 h periodic variation in the low-mass X-ray binary Ser X-1
No full textSpectroscopy of the low-mass X-ray binary Ser X-1 using the Gran Telescopio Canarias have revealed a ?2 h periodic variability that is present in the three strongest emission lines. We tentatively interpret this variability as due to orbital motion, making it the first indication of the orbital period of Ser X-1. Together with the fact that the emission lines are remarkably narrow, but still resolved, we show that a main-sequence K dwarf together with a canonical 1.4 M? neutron star gives a good description of the system. In this scenario, the most likely place for the emission lines to arise is the accretion disc, instead of a localized region in the binary (such as the irradiated surface or the stream-impact point), and their narrowness is due instead to the low inclination (?10°) of Ser X-1
Explicit time integration of the stiff chemical Langevin equations using computational singular perturbation
No full textA stable explicit time-scale splitting algorithm for stiff chemical Langevin equations (CLEs) is developed, based on the concept of computational singular perturbation. The drift term of the CLE is projected onto basis vectors that span the fast and slow subdomains. The corresponding fast modes exhaust quickly, in the mean sense, and the system state then evolves, with a mean drift controlled by slow modes, on a random manifold. The drift-driven time evolution of the state due to fast exhausted modes is modeled algebraically as an exponential decay process, while that due to slow drift modes and diffusional processes is integrated explicitly. This allows time integration step sizes much larger than those required by typical explicit numerical methods for stiff stochastic differential equations. The algorithm is motivated and discussed, and extensive numerical experiments are conducted to illustrate its accuracy and stability with a number of model systems
The continuity equation on metric measure spaces
No full textAim of this paper is to show that it makes sense to write the continuity equation on a metric measure space (X,d,m) and that absolutely continuous curves (\mu_t) w.r.t. the distance W_2 can be completely characterized as solutions of the continuity equation itself, provided we impose the condition μ_t ≤ Cm for every t and some C > 0
Relations between x-ray timing features and spectral parameters of galactic black hole x-ray binaries
No full textWe present a study of correlations between spectral and timing parameters for a sample of black hole X-ray binary candidates. Data are taken from GX
339-4, H 1743-322, and XTE J1650-500, as the Rossi X-ray Timing Explorer
(RXTE) observed complete outbursts of these sources. In our study we investigate outbursts that happened before the end of 2009 to make use of the high-energy coverage of the HEXTE detector and select observations that
show a certain type of quasi-periodic oscillations (type-C QPOs). The spectral parameters are derived using the empirical convolution model simpl to model the Comptonized component of the emission together with a disc blackbody for the emission of the accretion disc. Additional spectral features, namely a reflection component, a high-energy cut-off, and excess emission at 6.4 keV, are taken into account. Our investigations confirm the known positive
correlation between photon index and centroid frequency of the QPOs and reveal an anti-correlation between the fraction of up-scattered photons and the QPO frequency. We show that both correlations behave as expected in the “sombrero”
geometry. Furthermore, we find that during outburst decay the correlation between photon index and QPO frequency follow a general track, independent of individual outbursts
Nitrogen acquisition by plants and microorganisms in a temperate grassland
No full textNitrogen (N) limitation is common in most terrestrial ecosystems, often leading to strong competition between microorganisms and plants. The mechanisms of niche differentiation to reduce this competition remain unclear. Short-term N-15 experiments with NH4+, NO3-, and glycine were conducted in July, August and September in a temperate grassland to evaluate the chemical, spatial and temporal niche differentiation by competition between plants and microorganisms for N. Microorganisms preferred NH4+ and NO3-, while plants preferred NO3-. Both plants and microorganisms acquired more N in August and September than in July. The soil depth had no significant effects on microbial uptake, but significantly affected plant N uptake. Plants acquired 67% of their N from the 0-5 cm soil layer and 33% from the 5-15 cm layer. The amount of N taken up by microorganisms was at least seven times than plants. Although microorganisms efficiently compete for N with plants, the competition is alleviated through chemical partitioning mainly in deeper soil layer. In the upper soil layer, neither chemical nor temporal niche separation is realized leading to strong competition between plants and microorganisms that modifies N dynamics in grasslands
Stenoloba huanxipoa Han & Kononenko 2018, sp. n.
No full textStenoloba huanxipoa sp. n. (Figs 2, 3, 32, 33, 48) Type material. Holotype: male, China, Prov. Yunnan, Tengchong, Mt. Gaoligong, Huanxipo 1–3.viii.2014, H.L. Han leg., slide HHL-3182-1, coll. NEFU. Paratypes: 2 males, same locality, 18.vii.2012, H.L. Han, X. X. Jin & H. Cheng leg., slide HHL-6154-1; 3 males, 3 female, 3.viii.2014, same locality, H.L. Han leg., genit. slides: HHL- 3173-2, 3174-1; 3175-2; 3176-2; 3 males, 4, 6.viii.2014, same locality, H.L. Han & Z.P. Xiong leg.; 2 males, 1 female, same locality, 1–3.viii.2013, Z.H. Pan leg., slides HHL-3182-1S; 3183-2 [coll. NEFU]; 1 female, Aut. Reg. Xizang, Linzhi, Lulang Bingzhan, 26.vii.2013, H.L. Han, Z.G. Wu leg., slide HHL-2949-2, coll. NEFU; 2 males, Prov, Jiangxi, Guanshan Nature reserve, 21–23.viii.2017, H.L. Han leg.; 1 male, 1 female, Aut. Reg. Xizang, Linzhi, Pailong, 9.–10.viii.2017, H.L. Han leg.; 1 female, Aut. Reg. Xizang, Yigong, Shuangyu, 7.viii.2017, H.L. Han leg. Diagnosis. This and next species represent separate S. huanxipoa species-group, which could be characterized by structure of male genitalia, namely presence of developed uncus, shape of valva bearing dorsal extension of costa and structure of vesica with missing cornuti. There is no similar species among describe Stenoloba spp. The new species externally is characterized by green or ochre-green ground colour of forewing and characteristic dark blackish marks in the costal area outward antemedial line and opposite reniform; the last forms u-like mark. In male genitalia, valva constricted distally, costa with acute finger-like dorsal extension. Description. Adult (Figs 2, 3). Wingspan 24–26 mm. Head and thorax ochreous-green or salad-green, with whitish scales; ground colour of forewing ochreous-green or salad-green, wing pattern unsharp; basal field somewhat darker than background, bordered with blackish scales; subbasal fields ochre-green or salad-green; separated from medial field by wide oblique blackish stroke; orbicular as indistinct reddish point in base of stroke; reniform encircled with blackish scales on whitish background; two blackish strokes in costal field below reniform form u-like mark; subterminal line blackish, indistinct; subterminal field green with indistinct dashes, separated from terminal field by thin whitish line; terminal field green or green with blackish scales, with whitish apical mark; terminal line interrupted, as a row of small blackish streaks; cilia greyish with white. Hindwing yellowishgrey, darker to terminal margin; discal spot hardly traceable; cilia yellowish-grey, pale in base. Male genitalia (Figs 32, 33). Uncus present, moderate in length (about half of the length of tegumen); tegumen and vinculum thin, tegumen almost equal to vinculum; transtilla with broad sclerotised bands; juxta more or less leave-shaped; valva rather long, broad, with parallel margins basally, gradually constricted apically, with broad rounded sacculus and acute pointed apex; costa bearing acute finger-like extension in distal third, before apex. Aedeagus rather long, vesica tubular, extended in middle, with two large medial diverticula. Female genitalia (Fig. 48). Ovipositor weak, short; apophyses anteriores and posteriors ones equal in length; antrum sclerotised, long funnel-like, with sclerotised fields posteriorly; ductus bursae equal to antrum in width and length, flat, moderately long, sclerotised; corpus bursae moderate in length, rounded-elongate, membranous with short, slightly sclerotised appendix bursae. Etymology. The species name is referred to Huanxipo village, the type-locality of the new species. Distribution. Southwest China (Prov. Yunnan, Aut. Reg. Xizang and Prov. Jiangxi). The species is known only from its type-locality in Prov. Yunnan, where it occurs in mountains at elevation 1200–1500 m. Moths were collected in July.Published as part of Han, H. L. & Kononenko, V. S., 2018, Twelve new species and four new records of Stenoloba Staudinger 1892 from China (Lepidoptera, Noctuidae: Bryophilinae), pp. 301-327 in Zootaxa 4388 (3) on pages 303-304, DOI: 10.11646/zootaxa.4388.3.1, http://zenodo.org/record/118855
Discovery of an optical counterpart to the hyperluminous X-ray source in ESO 243-49
No full textThe existence of black holes of masses similar to 10(2)-10(5)M(circle dot) has important implications for the formation and evolution of star clusters and supermassive black holes. One of the strongest candidates to date is the hyperluminous X-ray source (HLX1), possibly located in the S0- a galaxy ESO 243-49, but the lack of an identifiable optical counterpart had hampered its interpretation. Using the Magellan telescope, we have discovered an unresolved optical source with R = 23.80 +/- 0.25 mag and V = 24.5 +/- 0.3 mag within HLX1's positional error circle. This implies an average X-ray/optical flux ratio similar to 500. Taking the same distance as ESO 243-49, we obtain an intrinsic brightness M-R = -11.0 +/- 0.3 mag, comparable to that of a massive globular cluster. Alternatively, the optical source is consistent with a main-sequence M star in the Galactic halo (for example an M4.4 star at approximate to 2.5 kpc). We also examined the properties of ESO 243-49 by combining Swift/Ultraviolet/Optical Telescope (UVOT) observations with stellar population modelling. We found that the overall emission is dominated by a similar to 5-Gyr-old stellar population, but the UV emission at approximate to 2000 angstrom is mostly due to ongoing star formation at a rate of similar to 0.03M(circle dot) yr(-1). The UV emission is more intense (at least a 9 sigma enhancement above the mean) north-east of the nucleus, in the same quadrant as HLX1. With the combined optical and X-ray measurements, we put constraints on the nature of HLX1. We rule out a foreground star and a background AGN. Two alternative scenarios are still viable. HLX1 could be an accreting intermediate mass black hole in a star cluster, which may itself be the stripped nucleus of a dwarf galaxy that passed through ESO 243-49, an event which might have caused the current episode of star formation. Or, it could be a neutron star in the Galactic halo, accreting from an M4-M5 donor star
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