3,467 research outputs found

    The Motivation of Capital-giving in Crowdfunding Market: A Self-determination Theory Perspective

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    How to promote crowd-funding results successfully are crucial to crowdfunding platforms and crowdfunding projects. The results of crowd-funding projects are determined by investors’ subjective behavior, which is triggered by some certain motivations. However, for different investors, the motivation toward a speculative behavior may be different. Thus, it is very necessary to explore and analyze the composition of the motivations behind each investor’s decision. In this paper, we identify different motivation modes mainly influenced by the project description, which will be beneficial to identify the investment intention of each investor. Based on the self-determination theory, we first create the corpus targeting different motives by means of the text mining method. Then, we classify the project description and project investment options. Last, we conduct an econometric model to examine the effect of investor’s motives on crowd-funding results based on the real dataset from Indiegogo Platform

    Inward currents induced by ischemia in rat spinal cord dorsal horn neurons

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    Hypoxia and ischemia occur in the spinal cord when blood vessels of the spinal cord are compressed under pathological conditions such as spinal stenosis, tumors, and traumatic spinal injury. Here by using spinal cord slice preparations and patch-clamp recordings we investigated the influence of an ischemia-simulating medium on dorsal horn neurons in deep lamina, a region that plays a significant role in sensory hypersensitivity and pathological pain. We found that the ischemia-simulating medium induced large inward currents in dorsal horn neurons recorded. The onset of the ischemia-induced inward currents was age-dependent, being onset earlier in older animals. Increases of sensory input by the stimulation of afferent fibers with electrical impulses or by capsaicin significantly speeded up the onset of the ischemia-induced inward currents. The ischemia-induced inward currents were abolished by the glutamate receptor antagonists CNQX (20 μM) and APV (50 μM). The ischemia-induced inward currents were also substantially inhibited by the glutamate transporter inhibitor TBOA (100 μM). Our results suggest that ischemia caused reversal operation of glutamate transporters, leading to the release of glutamate via glutamate transporters and the subsequent activation of glutamate receptors in the spinal dorsal horn neurons

    New geochronological and provenance constraints on the Late Mesozoic sedimentary formations in the western Shandong Province and Tanlu fault zone, China

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    We present new LA-ICP-MS detrital zircon U-Pb age and trace element data of the Late Mesozoic sedimentary sequences from the western Shandong and Tanlu fault zone, with the aim to constrain the depositional ages and sedimentary sources. The samples from the western Shandong have similar U-Pb age spectra, which can be divided into three major age groups, peaking age at circa 2,475–2,540 Ma, 1820–1870 Ma and 257–285 Ma, with minor Mesoproterozoic, Neoproterozoic and Paleozoic detrital zircon grains. The sample JN recovered from the Tanlu fault zone has an overwhelming majority of the Early Cretaceous detrital zircons with the age peak at circa 125 Ma, whereas the Archean and Paleoproterozoic detrital zircons are subordinate. The weighted average age of the youngest zircons show that the Santai Formation probably had begun deposition at circa 158 Ma and terminated deposition at circa 150 Ma, and the Tianjialou Formation of the Dasheng Group had begun deposition at circa 122 Ma. Our study indicates that the activity of the dinosaurs might occur during the Late Jurassic rather than the Cretaceous in the Shandong province. In addition, most detrital zircons of the studied samples are characterized by the high Th/U ratios and left-inclined REE patterns, revealing a magmatic origin. Morphologically, most detrital zircon grains characterized by angular to sub-rounded shapes indicate a middle-short distance transport from the source regions, whereas minor detrital zircon grains show rounded shapes, indicating a long-distance transport or multiphase recycling. According to detrital age populations in this study, combined with previously published data, we conclude that depositional provenances of the Santai Formation were mainly derived from the western Shandong and Jiao-Liao Belt, and minor detritus were derived from the northern part of the North China Craton and Xing-Meng orogenic belt. The sediments deposited in the Tanlu fault zone were mainly derived from the volcanic and subvolcanic rocks of the Qingshan period in the eastern Shandong, and subordinate depositional sources were from the Jiao-Liao and the basement uplift of the western Shandong, with minor supplier being derived from the Yinshan-Yanshan orogenic belt. The detrital provenance of the Santai Formation indicates that extension of the eastern NCC occurred during the Late Jurassic. The Neoproterozoic detrital zircons play a minor role in the studied strata, indicating that the large sinistral movement of the Tanlu fault zone might have occurred at the Early-Middle Jurassic and formed a paleogeographic separation of the western Shandong and eastern Shandong (Sulu orogenic belt)

    The mitochondrial alternative oxidase pathway protects the photosynthetic apparatus against photodamage in Rumex K-1 leaves

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    <p>Abstract</p> <p>Background</p> <p>It is known that excess reducing equivalents in the form of NADPH in chloroplasts can be transported via shuttle machineries, such as the malate-oxaloacetate (OAA) shuttle, into the mitochondria, where they are efficiently oxidised by the mitochondrial alternative oxidase (AOX) respiratory pathway. Therefore, it has been speculated that the AOX pathway may protect plants from photoinhibition, but the mechanism by which this protection occurs remains to be elucidated.</p> <p>Results</p> <p>The observation that the malate-OAA shuttle activity and the AOX pathway capacity increased markedly after intense light treatment in <it>Rumex </it>K-1 leaves indicates that excess NADPH was transported from the chloroplasts and oxidised by the AOX pathway. The inhibition of the AOX pathway by salicylhydroxamic acid (SHAM) caused the over-reduction of the photosystem I (PSI) acceptor side, as indicated by the increases in the extent of reduction of P700<sup>+</sup>. Furthermore, the photosynthetic linear electron flow was restricted, which was indicated by the decreases in the PSII electron transport rate (ETR) and the photosynthetic O<sub>2 </sub>evolution rate. The restriction of the photosynthetic linear electron flow, which generates the thylakoid ΔpH, inevitably decreased the de-epoxidation of the xanthophyll cycle (ΔPRI). Therefore, the induction of non-photochemical quenching (NPQ) was suppressed when the AOX pathway was inhibited. The effect of the inhibition of the AOX pathway on NPQ induction was less at 20 mM NaHCO<sub>3 </sub>than at 1 mM NaHCO<sub>3</sub>. The suppression of NPQ induction by the inhibition of the AOX pathway was also observed during the induction phase of photosynthesis. In addition, the inhibition of the AOX pathway increased the accumulation of hydrogen peroxide (H<sub>2</sub>O<sub>2</sub>), suggesting that the AOX pathway functions as an antioxidant mechanism.</p> <p>Conclusions</p> <p>The inhibition of the AOX pathway resulted in the rapid accumulation of NADPH in the chloroplasts, which caused the over-reduction of the PSI acceptor side. Furthermore, the restriction of the photosynthetic linear electron flow due to the inhibition of the AOX pathway limited the generation of the thylakoid ΔpH and suppressed the induction of NPQ. Therefore, the mitochondrial AOX pathway protected the photosynthetic apparatus against photodamage by alleviating the over-reduction of the PSI acceptor side and accelerating the induction of NPQ in <it>Rumex </it>K-1 leaves.</p

    Ba-enhanced dwarf and subgiant stars in the LAMOST Galactic surveys

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    Ba-enhanced stars are interesting probes of stellar astrophysics and Galactic formation history. In this work, we investigate the chemistry and kinematics for a large sample of Ba-enhanced ([Ba/Fe]>>1.0) dwarf and subgiant stars with 5000<Teff<67005000 < T_{\rm eff }< 6700\,K from LAMOST. We find that both stellar internal evolution process and external mass exchange due to binary evolution are responsible for the origins of the Ba-enhancement of our sample stars. About one third of them exhibit C and N enhancement and ultraviolet brightness excess, indicating they are products of binary evolution. The remaining Ba-enhanced stars with normal C and N abundances are mostly warm stars with Teff>6000T_{\rm eff} > 6000\,K. They are likely consequences of stellar internal elemental transport processes, but they show very different elemental patterns to the hotter Am/Fm stars. Our results reveal a substantially lack of high-[α\alpha/Fe] Ba-enhanced stars in the [Fe/H]--[α\alpha/Fe] plane, which we dub as a {\em high-α\alpha desert}. We suggest it is due to a lower efficiency for producing Ba-enhanced stars by low-mass AGB progenitors in binary systems. Our results call for detailed modellings for these Ba-enhanced stellar peculiars, in the context of both stellar internal elemental transport and external mass accretion.Comment: 20 pages, 17 figures. Accepted for publication in Ap

    Radiative transitions in charmonium from Nf=2N_f=2 twisted mass lattice QCD

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    We present a study for charmonium radiative transitions: J/ψηcγJ/\psi\rightarrow\eta_c\gamma, χc0J/Ψγ\chi_{c0}\rightarrow J/\Psi\gamma and hcηcγh_c\rightarrow\eta_c\gamma using Nf=2N_f=2 twisted mass lattice QCD gauge configurations. The single-quark vector form factors for ηc\eta_c and χc0\chi_{c0} are also determined. The simulation is performed at a lattice spacing of a=0.06666a= 0.06666 fm and the lattice size is 323×6432^3\times 64. After extrapolation of lattice data at nonzero Q2Q^2 to 0, we compare our results with previous quenched lattice results and the available experimental values.Comment: typeset with revtex, 15 pages, 11 figures, 4 table
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