29,462 research outputs found
Lathrobium longwangshanense Peng, L.
No full textLathrobium longwangshanense Peng, L. -Z. Li & M.-J. Zhao, 2012 Material studied. China: Zhejiang: 4 ♂♂, 1 ♀, Anji County, Longwang Shan, 30°24'N 119°26'E, 1250–1450 m, 14. V.2013, Liang Tan leg. (SNUC); 1 ♂, Lin’an, Tianmu Shan, 30°20'50''N 119°25'58''E, 1300 m, 22.X.2013, Bi, Song, Tang & Yin leg. (SNUC). Comment: Lathrobium longwangshanense Peng, L. -Z. Li & M.-J. Zhao, 2012 has been recorded from several localities in Tianmu Shan and Longwang Shan, Zhejiang (Peng et al., 2012; Peng et al., 2014). For illustrations of L. longwangshanense see Peng et al. (2012c: figures 1B, 4; 2014: 24D–F).Published as part of Zhao, Qing-Hao & Peng, Zhong, 2021, New species and new records of the genus Lathrobium Gravenhorst (Coleoptera Staphylinidae: Paederinae) from Zhejiang, East China, pp. 172-181 in Zootaxa 4990 (1) on pages 176-177, DOI: 10.11646/zootaxa.4990.1.11, http://zenodo.org/record/498258
Lathrobium zhui Peng & Li 2014
No full textLathrobium zhui Peng & Li, 2014 (Figs 1 D–F) Material studied. China: Zhejiang: 2 ♂♂, 7 ♀♀, Qingyuan, Baishanzu Natural Reserve, 27 ° 45 ' 26 ''N 119 ° 12 '08''E, 1730 m, 02.V. 2014, Peng, Song, Yan & Yu leg. (SNUC); 4 ♂♂, 12 ♀♀, Qingyuan, Baishanzu Natural Reserve, 27 ° 45 ' 14 ''N 119 ° 11 ' 55 ''E, 1560–1750 m, 01.V. 2014, Peng, Song, Yan & Yu leg. (SNUC). Comment. The original description is based on two males. The previously unknown female sexual characters are as follows: posterior margin of tergite VIII (Fig. 1 D) weakly convex; sternite VIII (Fig. 1 E) longer than that of male, middle of apical margin with pronounced apically convex projection; tergite IX (Fig. 1 F) with short anteromedian portion and moderately long postero-lateral processes; tergite X (Fig. 1 F) approximately 4.6 times as long as antero-median portion of tergite IX. For illustrations of the habitus and the male sexual characters see Peng et al. (2012 a).Published as part of Peng, Zhong, Li, Qi-Li, Shen, Liang & Gu, Fu-Kang, 2015, On the Lathrobium fauna of the Donggong Mountains, eastern China, pp. 245-263 in Zootaxa 3905 (2) on page 250, DOI: 10.11646/zootaxa.3905.2.6, http://zenodo.org/record/24508
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
Relations between x-ray timing features and spectral parameters of galactic black hole x-ray binaries
Full text linkWe 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
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
Identification and attenuation of slat noise
Full text linkIn the case of civil transport aircraft, engines were the dominant noise source until the advent of the high-bypass ratio engines in the early 1970s. Since then, airframe noise has become more important, particularly during the approach-to-landing stage of aircraft operations. The main components of airframe noise are the flap side edge, leading edge slat, and the landing gear. Experiments in both the wind tunnel and via fly-over measurements have shown that the slat noise is a major contributor to the overall airframe noise during the landing approach for a commercial aircraft.To achieve the goal of reducing slat noise significantly without adversely affecting the aerodynamic performance of the wing, it is obligatory to improve the understanding of the mechanism of slat noise generation. Experiments and numerical simulations were performed to investigate the phenomena of slat noise. It was found that the slat broadband noise generation is governed by two kinds of mechanism. At a low angle of attack of the wing, the typical circulation region is not formed in the slat cove and the slat noise level is low. As the angle of attack increases to a certain value, vortical structures are intermittently generated due to flow interaction occurring between the shear layer originating from the slat cusp and the flow convected from the stagnation line on the main element. Intense slat noise is produced as the vortical structures approach the slat cove surface. With the angle of attack increasing further, the slat noise becomes weak again. The interaction effect tends to become weaker as the shear layer deviates away from the surface of the main element.Two approaches with the aim of attenuating the slat noise were experimentally and numerically studied. The first approach was to reduce the slat noise using air blown on the suction surface of the slat near its trailing edge. A numerical simulation showed that the slat noise levels over most of the frequencies, especially above a St number of 7, were obviously attenuated. In the second approach, a strip mounted on the pressure surface of the main element model was experimentally proven to be an effective method for reducing the broadband slat noise at an angle of attack of 8 degrees and a freestream velocity of 25 m/s. The position and height of the strip also influenced the level of the reduction.Several tonal noise components appear in the slat noise spectrum at an angle of attack of 4 degrees and a freestream velocity of 25 m/s. The dominant tone is associated with the vortex shedding off the slat cusp through the Kelvin-Helmholtz instability. This tone was successfully suppressed using a plasma actuator employing an open-loop control. A maximum reduction of 11 dB was achieved at a St number of approximately 19.7. A quasi-static feedback control system was also developed, wherein a controller is responsible for calculating the control inputs in terms of feedback signals. The experimental results show that the controller can work effectively to suppress the slat noise
Lathrobium yangshimuense Peng
No full textLathrobium yangshimuense Peng and L.-Z. Li, new species (Map 1, Figs 9 B, 11) Type material. HOLOTYPE: Ƌ, labeled ‘ China: Jiangxi Prov., Luxi County, Yangshimu, 27°35'07''N 114°15'41''E, 1360 m, 24.X.2013, Peng, Shen & Yan leg.’ (SNUC). Paratypes: 1 Ƌ, same label data as holotype (SNUC); 1 ♀, same data, but ‘ 27°34'25''N 114°14'14''E, 910–1550 m, 16.VII.2013, Song, Yin & Yu leg.’ (SNUC). Description. Measurements (in mm) and ratios: BL 7.42–7.58, FL 3.07–3.12, HL 0.80–0.83, HW 0.78–0.81, AnL 1.67–1.79, PL 1.04–1.10, PW 0.83–0.86, EL 0.59–0.67, AL 1.11, HL/HW 1.00–1.02, HW/PW 0.93–0.94, HL/PL 0.75–0.77, PL/PW 1.25–1.28, EL/PL 0.57–0.61. Habitus as in Fig. 9 B. Body reddish brown, legs yellowish brown, antennae reddish brown to yellowish brown. Head: punctation coarse and moderately dense, and distinctly sparser in median dorsal portion; interstices with distinct microreticulation. Eyes small and composed of approximately 30 ommatidia. Pronotum parallel-sided; punctation sparser than that of head; impunctate midline broad; interstices without microsculpture. Elytral punctation moderately dense and shallow. Hind wings completely reduced. Protarsi with distinct sexual dimorphism. Abdomen with fine and dense punctation, punctation of tergite VII slightly less sparse than that of anterior tergites; interstices with shallow, but distinct microsculpture; posterior margin of tergite VII without palisade fringe; tergite VIII without sexual dimorphism, posterior margin (Fig. 11 A) convex in both sexes. Male. Sternites III–VI unmodified; sternite VII (Fig. 11 D) strongly transverse, with very shallow median depression posteriorly, this impression without distinctly modified setae, posterior margin broadly concave; sternite VIII (Fig. 11 E) oblong and symmetric, with longitudinal impression extending along whole sternite, middle of sternite narrowly without setae, posterior excision V-shaped and stout, at margins with blackish setae; aedeagus as in Figs 11 F, G; ventral process weakly asymmetric in ventral view and apically acute; dorsal plate with long and strongly sclerotized apical portion, and with thin basal portion; internal sac with a long sclerotized spine. Female. Sternite VIII as in Fig. 11 B, posterior margin distinctly convex; tergite IX (Fig. 11 C) with divided median portion and moderately long postero-lateral processes; tergite X (Fig. 11 C) 4.8 times as long as anteromedian portion of tergite IX. Comparative notes. The new species resembles L. badagongense Peng & Li, 2014 from Badagong Shan, Hunan in the shape of the male sternite VIII, the morphology of the aedeagus (shape of ventral process; distinctly sclerotized apical portion of dorsal plate) and the female sexual characters (shape of sternite VIII; divided median portion of tergite IX). It is distinguished from L. badagongense by reddish brown coloration, the chaetotaxy of the male sternite VIII, the internal structures of the aedeagus, as well as the shape of the female tergite VIII. For illustrations of L. badagongense see Peng et al. (2014). Distribution and natural history. The species was collected in two localities in Yangshimu to the east of Luxi, western Jiangxi. The specimens were sifted from leaf litter in a coniferous forest at altitudes between 910 and 1550 m, partly together with L. taiye. Etymology. The species is named after its type locality (Yangshimu).Published as part of Peng, Zhong, Li, Li-Zhen & Zhao, Mei-Jun, 2016, On the Lathrobium fauna of the Luoxiao Mountains, Central China, pp. 385-402 in Zootaxa 4158 (3) on pages 398-400, DOI: 10.11646/zootaxa.4158.3.5, http://zenodo.org/record/27221
Correlated X-ray/ultraviolet/optical variability in the very low mass AGN NGC 4395
Full text linkWe report the results of a 1-yr Swift X-ray/ultraviolet (UV)/optical programme monitoring the dwarf Seyfert nucleus in NGC4395 in 2008-2009. The UV/optical flux from the nucleus was found to vary dramatically over the monitoring period, with a similar pattern of variation in each of the observed UV/optical bands (spanning 1900-5500 Å). In particular, the luminosity of NGC4395 in the 1900 Å band changed by more than a factor of 8 over the monitoring period. The fractional variability was smaller in the UV/optical bands than that seen in the X-rays, with the X-ray/optical ratio increasing with increasing flux. Pseudo-instantaneous flux measurements in the X-ray and each UV/optical band were well correlated, with cross-correlation coefficients of ≥0.7, significant at 99.9per cent confidence. Archival Swift observations from 2006 sample the intra-day X-ray/optical variability on NGC4395. These archival data show a very strong correlation between the X-ray and b bands, with a cross-correlation coefficient of 0.84 (significant at >99per cent confidence). The peak in the cross-correlation function is marginally resolved and asymmetric, suggesting that X-rays lead the b band, but by ≤1h. In response to recent (2011 August) very high X-ray flux levels from NGC4395 we triggered Swift target of opportunity observations, which sample the intra-hour X-ray/UV variability. These observations indicate, albeit with large uncertainties, a lag of the 1900 Å band behind the X-ray flux of ∼400s. The tight correlation between the X-ray and UV/optical lightcurves, together with the constraints we place on the lag time-scale, is consistent with the UV/optical variability of NGC4395 being primarily due to reprocessing of X-ray photons by the accretion disc
Lathrobium haoae Peng and Li, new species
No full textLathrobium haoae Peng and Li, new species (Figs 2 C, 5) Type material. HOLOTYPE: ♂, labeled ‘ China: Zhejiang Prov., Lishui City, Longquan, Fengyang Shan, 27 ° 55 ' 47 ''N 119 ° 10 ' 38 ''E, 1570 m, 26.IV. 2014, Peng, Song, Yan, Yin & Yu leg.’ (SNUC). Paratypes: 2 ♂♂, 2 ♀♀, same label data as holotype (SNUC); 2 ♂♂, same data, but ‘ 27 ° 54 ' 33 ''N 119 ° 10 ' 20 ''E, 1170–1300 m, 07.X. 2013, Feng, Peng, Yin & Yu leg’ (SNUC); 1 ♂, 1 ♀, same data, but ‘ 27 ° 53 ' 59 ''N 119 °09' 41 ''E, 1700 m, 08.X. 2013, Peng, Yin & Yu leg.’ (SNUC); 6 ♂♂, 11 ♀♀, same data, but ‘ 27 ° 53 ' 22 ''N 119 ° 10 ' 25 ''E, 1500 m, 05.X. 2013, Feng, Peng & Yu leg.’ (SNUC); 2 ♀♀, same data, but ‘ 27 ° 54 'N 119 ° 13 'E, 1450–1600 m, 22.VII. 2006, Li & Shen leg.’ (SNUC); 1 ♂, 1 ♀, same data, but ‘ 27 ° 55 'N 119 ° 14 'E, 1500–1700 m, 27.VII. 2006, Li & Shen leg.’ (SNUC). Description. Measurements (in mm) and ratios: BL 8.34–10.73, FL 4.45–5.17, HL 1.13–1.26, HW 1.30–1.42, AnL 2.45–2.61, PL 1.67–1.86, PW 1.41–1.52, EL 0.85–0.97, AL 1.91–1.97, HL/HW 0.86–0.90, HW/PW 0.90–0.94, HL/PL 0.66–0.69, PL/PW 1.18–1.23, EL/PL 0.50–0.53. Habitus as in Fig. 2 C. Body blackish brown, legs brown, antennae dark brown. Head transverse, weakly dilated posteriorly; punctation coarse and sparse, and distinctly sparser in median dorsal portion; interstices with shallow microreticulation. Eyes large and composed of approximately 60 ommatidia. Pronotum with weakly convex lateral margins in dorsal view; punctation somewhat sparser than that of head; impunctate midline rather broad; interstices without microsculpture. Elytral punctation moderately dense and weakly defined. Hind wings completely reduced. Protarsi without appreciable sexual dimorphism, distinctly dilated. Abdomen with moderately fine and moderately dense punctation, punctation of tergite VII sparser than that of anterior tergites; interstices with shallow microsculpture; posterior margin of tergite VII without palisade fringe; tergite VIII without sexual dimorphism, posterior margin (Fig. 5 A) broadly convex. Male. Sternite III unmodified; sternite IV (Fig. 5 D) with dense dark setae in large postero-median impression; sternite V (Fig. 5 E) similar to sternite IV, but with longer setae in somewhat larger impression and at middle of posterior margin with cluster of several point-like setae; sternite VI (Fig. 5 F) similar to sternite IV, but with larger impression and at middle of posterior margin with cluster of numerous point-like setae; sternite VII (Fig. 5 G) strongly transverse, with very shallow median impression posteriorly, this impression without distinctly modified setae, posterior margin broadly concave; sternite VIII (Fig. 5 H) with triangular, symmetric posterior excision and short dark setae in narrow impression; aedeagus as in Figs 5 I, J, ventral process distinctly asymmetric and moderately long; dorsal plate sclerotized, with broad, large apical portion and with thin basal portion; internal sac with single long strongly sclerotized spine and series of moderately sclerotized spines. Female. Sternite VIII as in Fig. 5 B, middle of apical margin with apically convex projection; tergite IX (Fig. 5 C) with very short antero-median portion and short postero-lateral processes; tergite X (Fig. 5 C) 6.5 times as long as antero-median portion of tergite IX. Comparative notes. As can be inferred from the similarly derived shapes and chaetotaxy of the male sternite VIII, the similarly derived structure of the aedeagus, as well as from the similar female sexual characters, L. haoae is probably closely allied to the geographically close L. zhui Peng & Li, 2014. It differs from L. zhui by the smaller postero-median impression on the male sternite IV, the longer modified setae on the male sternite V, the dense dark setae in the large postero-median impression and the numerous point-like setae on the male sternite VI, the broadly concave posterior margin of the male sternite VII, and the slightly larger aedeagus (L. zhui: length of aedeagus 1.82–1.86 mm) with a somewhat stouter ventral process. For illustrations of L. zhui see Figs 1 D–F and Peng et al. (2012 a). Distribution and biological notes. The type locality is situated in the Fengyang Shan to the south of Longquan, southern Zhejiang. The specimens were sifted from leaf litter, moss and humus in deciduous forests with bamboo at altitudes of 1170–1700 m, partly together with L. immanissimum, L. yui and/or L. obstipum. Etymology. This species is named for Mrs. Cai-Qin Hao, the first author’s wife, who supported us on our field trips.Published as part of Peng, Zhong, Li, Qi-Li, Shen, Liang & Gu, Fu-Kang, 2015, On the Lathrobium fauna of the Donggong Mountains, eastern China, pp. 245-263 in Zootaxa 3905 (2) on pages 250-252, DOI: 10.11646/zootaxa.3905.2.6, http://zenodo.org/record/24508
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