69,128 research outputs found
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
Magnetostructural investigations into an S=1/2 sheet and a tetranuclear butterfly cluster
No full textWe present a detailed analysis of the magnetic properties of two Cu(II) coordination compounds with the tetrazole-1-acetate ligand (t1a), previously reported in literature by Yu et al. [Q. Yu, X. Zhang, H. Bian, H. Liang, B. Zhao, S. Yan, D. Liao, Cryst. Growth Des. 8 (2008) 1140] and simultaneously synthesised independently by ourselves. We focus on methods of describing the susceptibility and magnetisation of a ferromagnetically-coupled S = 1/2 square network (2) and a tetranuclear S = 1/2 'butterfly' cluster (4) as well as discussion of the energy levels of such a cluster
"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.
Magnetic properties and giant magnetoresistance in magnetic granular Cox Cu100-x alloys
No full textMagnetic granular CoxCu100-x alloys (x = 5-20) have been prepared by melt-spinning acid subsequently annealing at 450 degrees C for 30 min, which is most appropriate for obtaining the largest MR change with magnetic field in each sample. The highest magnetoresistance (MR) change of 42.5% was observed in annealed Co15CU85 ribbons. Based on the superparamagnetic assumption, the average size of Co particles embedded in a Cu-rich matrix for different samples, ranging from 3.5 to 5.5 nm, has been estimated by simulating the magnetization curves at room temperature which is higher than the blocking temperature T-B for each sample. The value of MR change was found to strongly depend on the Co composition and annealing temperature
Persistent high-growth firms in China’s manufacturing
No full textThis article explores the association between persistence of high-growth and crucial dimensions of firm structure and performance (productivity, profits, investment patterns, innovation, and financial structures) to shed light on what makes a persistent high-growth firm. We employ a multidimensional definition of a high-growth firm that simultaneously accounts for growth of sales and employment, and design an empirical strategy that seeks to capture the “long-run” ability of high-growth firms to replicate their high-growth performance over time. Exploiting a large panel covering the period of the China’s miracle, we find that none of the considered firm attributes stands out as distinctive feature of persistent high-growth. This finding casts doubts on the long-run contribution of high-growth firms, in turn challenging the long-run effectiveness of policies supporting the creation and expansion of such firms
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
Calorie elasticities with income dynamics: Evidence from the literature
No full textThis paper proposes a finite mixture model (FMM) to model the behavioral transition of calorie consumption with an assumption that nutrition consumption is a mixture of two different behavioral stages: a poor stage and an affluent stage. Based on 387 calorie-income elasticities collected from 90 primary studies, our results identify that the threshold income for calorie demand transition is 459.8 USD in 2012 prices (PPP). It implies that the transitional threshold for calorie consumption is 1.26 dollar/day, which is slightly lower than the World Bank poverty line (1.25 dollar/day in 2005 PPP prices)
Xylochrysis aquatica J. Y. Song & X. D. Yu
No full text<i>Xylochrysis aquatica</i> J.Y. Song & X.D. Yu <i>sp. nov.</i> (FIG. 2) <p> <i>MycoBank</i>: MB844596</p> <p> <i>Etymology</i>: In reference to the aquatic habitat of the fungus</p> <p> <i>Holotype</i>: HKAS 124019</p> <p> <i>Saprobic</i> on submerged decaying wood in a freshwater stream. <b>Sexual morph:</b> <i>Ascomata</i> 160–265 µm diam. × 145– 290 µm high (<i>x</i> = 200 µm × 205 µm, n = 10), solitary, scattered, immersed to slightly erumpent, globose to subglobose, nonstromatic, uniloculate, glabrous, without a golden yellow layer of surrounding cells at the basal venter, ostiolate. <i>Ostiole</i> 65–135 µm long, 65–130 µm diam. (<i>x</i> = 108 µm × 96 µm, n = 10), black, papillate, glabrous, shiny, lined with hyaline periphyses. <i>Ascomatal wall</i> multi-layered, outer layers 12–47 µm thick, composed of brown to dark brown cells of <i>textura angularis</i>, carbonized and form a thicker layer in the lower part of the ostiole, inner layers 13–33 µm, comparatively thick, composed of flattened, hyaline cells of <i>textura prismatica</i>. <i>Hamathecium</i> 2.5–5.0 µm wide (<i>x</i> = 4.0 µm, n = 30), comprising numerous, narrowly cylindrical to filiform, branched, septate paraphyses, not embedded in a gelatinous matrix. <i>Asci</i> 68–120 µm × 3.0–6.5 µm (<i>x</i> = 96.0 × 4.5 µm, n = 30), 8-spored, unitunicate, cylindrical, long pedicellate, tapering to the bulbose base, apically rounded with an apical ring. <i>Ascospores</i> 4.5–6.5 µm × 2.5–4.0 µm (<i>x</i> = 6.0 × 3.0 µm, n = 30), L/W 1.5–2.5 (<i>x</i> = 2.0, n = 30), uniseriate, ellipsoidal, hyaline, aseptate, straight, 2-guttulate, thin-walled, smooth-walled, without mucilaginous sheath or appendages. <b>Asexual morph:</b> Undetermined.</p> <p> <i>Culture characteristics:</i> Ascospores germinated on PDA within 24 hours, and germ tubes were produced from both ends of the ascospores. Colonies growing on PDA reaching a diameter of 20 mm after 24 days at 25 °C, rough, irregular, slightly raised, edge crenate, with both surfaces dark-gray in the margin and grayish-white towards the center, slowly growing, reverse taupe brown, without sporulation.</p> <p> <i>Material Examined:</i> CHINA, Sichuan province, Chengdu, Pengzhou county, Huilonggou Scenic Area, (31°14′21″ N, 103°47′28″ E), on a submerged decaying wood of undetermined host, 28 July 2021, Xian-Dong Yu (HKAS 124019, <b>holotype</b>; HUEST 22.0028, <b>isotype</b>); ex-type culture CGMCC 3.23639 (= UESTCC 22.0030).</p> <p> <i>Notes: Xylochrysis aquatica</i> fits well with the morphological characteristics of <i>Xylochrysis</i> in having globose ascomata, numerous paraphyses, cylindrical and long pedicellate asci, ellipsoidal and hyaline ascospores (Réblová <i>et al.</i> 2014). <i>Xylochrysis aquatica</i> is easily distinguished from the type species <i>X. lucida</i> by solitary, scattered, smaller ascomata (160–265 µm × 145–290 µm vs. 350–500 µm × 350–500 µm) without a layer of colored cells surrounded, longer asci (60–120 µm long vs. 59–73 µm long) and more rounded ascospores (L/W: 1.5–2.5 µm vs. 2.2–2.8 µm). Ascomata of <i>X. lucida</i> often aggregated or confluent in groups of 3–10 and surrounded by a golden yellow layer of cells. In addition, the ostiolar neck of <i>X. lucida</i> is short-beaked and distinctly longer (Réblová <i>et al.</i> 2014) than our new taxon, <i>X. aquatica</i>. The multi-gene (ITS-LSU-SSU- <i>tef1-α -rpb2</i>) phylogenetic analyses suggested that our isolate clustered together with the generic type <i>X. lucida</i> and formed a distinct lineage (100% ML; 1.00 PP) in <i>Woswasiaceae</i>. In addition, a nucleotide comparison of <i>X. aquatica</i> (CGMCC 3.23639) and <i>X. lucida</i> (CBS 135996) revealed 25 basepair (5 %) and 70 base-pair (7.2 %) differences in ITS (+ 5.8S) and <i>rpb2</i>, respectively (TABLE 2). <i>Xylochrysis aquatica</i> is introduced as a new species based on the moprhology and phylogeny evidences.</p>Published as part of <i>Song, Jing-Yi, Yang, Yi, Yu, Xian-Dong, Dissanayake, Asha J. & Tian, Qing, 2023, Xylochrysis aquatica sp. nov. (Woswasiaceae) from freshwater habitats in Sichuan Province, China, pp. 31-38 in Phytotaxa 587 (1)</i> on pages 34-35, DOI: 10.11646/phytotaxa.587.1.4, <a href="http://zenodo.org/record/7710702">http://zenodo.org/record/7710702</a>
Tang lei han: er bai juan, mu lu [er juan]. v.1
No full text俞安期彙纂 ; 徐顯卿校訂.綫裝, 1函.框20.9x14.6公分, 10行20字, 小字雙行同, 上白口下黑口, 單黑魚尾, 四周單邊. 版心上鐫部首, 中鐫卷次, 下鐫葉次及小題.刻書年據序.《目錄》分上, 下卷.Xian zhuang, 1 han.Kuang 20.9 x 14.6 gong fen, 10 hang 20 zi, xiao zi shuang hang tong, shang bai kou xia hei kou, dan hei yu wei, si zhou dan bian. Ban xin shang juan bu shou, zhong juan juan ci, xia juan ye ci ji xiao ti.Ke shu nian ju xu."Mu lu" fen shang, xia juan.Yu Anqi hui zuan ; Xu Xianqing jiao ding
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Enhanced colour encoding of materials discrimination information for multiple view dual-energy x-ray imaging
No full textThis thesis reports an investigation into dual-energy X-ray discrimination techniques. These techniques are designed to provide colour-coded materials discrimination information in a sequence of perspective images exhibiting sequential parallax. The methods developed are combined with a novel 3D imaging technique employing depth from motion or kinetic depth effect (KDE). This technique when applied to X-ray images is termed KDEX imaging and was developed previously by the university team for luggage screening applications at security checkpoints. A primary motivation for this research is that the dual-energy X-ray techniques, which are routinely incorporated into ‘standard’ 2D luggage scanners, provide relatively crude materials discrimination information. In this work it was critical that robust materials discrimination and colour encoding process was implemented as the sequential parallax exhibited by the KDEX imagery may introduce colour changes, due to the different X-ray beam paths associated with each perspective image. Any introduction of ‘colour noise’ into the resultant image sequences could affect the perception of depth and hinder the ongoing assessment of the potential utility of the dual-energy KDEX technique. Two dual-energy discrimination methods have been developed, termed K-II and W-E respectively. Employing the total amount of attenuation measured at each energy level and the weight fraction of layered structures, a combination of the K-II and the W-E techniques enables the computation and extraction of a target objects’ effective atomic number (Zeff) and its surface density (ρS) in the presence of masking layers
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