200 research outputs found

    Learners' harmonic preferences are modulated by lexical retrieval difficulty

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    Typological work has established the existence of language universals – features or combinations of features that (co-)occur in unrelated languages more frequently than expected by chance. The origins of language universals are a fundamental question in language sciences as these universals are considered a reflection of cognitive mechanisms underlying human language. In this study, we use a miniature artificial language learning paradigm to explore whether a well-known universal – a preference for harmonic word ordering between adpositional and verb phrases (i.e., placing the head in a consistent position with respect to the complements across the two phrase types) – originates in biases during language learning and whether this preference interacts with memory constraints (operationalized as lexical retrieval difficulty). We first trained participants on miniature languages containing adpositional phrases of a deterministic word order (either prepositional or postpositional inputs) and then briefly exposed them to simple transitive sentences (verb-subject-object and subject-object-verb order, equally frequent in the input). At test, we asked learners to describe simple transitive scenes. We found that in the hard lexical retrieval condition, learners exposed to a postpositional language showed a preference for harmonic ordering but learners of the prepositional language did not, which is only partially consistent to the typological distribution. In the easy lexical retrieval condition, learners of neither the postpositional nor prepositional language showed a preference for harmonic ordering, indicating that this preference is modulated by memory constraints

    Anti-DKK1 Enhances the Early Osteogenic Differentiation of Human Adipose-Derived Stem/Stromal Cells

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    : Adipose-derived stem/stromal cells (ASCs) have been previously used for bone repair. However, significant cell heterogeneity exists within the ASC population, which has the potential to result in unreliable bone tissue formation and/or low efficacy. Although the use of cell sorting to lower cell heterogeneity is one method to improve bone formation, this is a technically sophisticated and costly process. In this study, we tried to find a simpler and more deployable solution-blocking antiosteogenic molecule Dickkopf-1 (DKK1) to improve osteogenic differentiation. Human adipose-derived stem cells were derived from = 5 samples of human lipoaspirate. In vitro, anti-DKK1 treatment, but not anti-sclerostin (SOST), promoted ASC osteogenic differentiation, assessed by alizarin red staining and real-time polymerase chain reaction (qPCR). Increased canonical Wnt signaling was confirmed after anti-DKK1 treatment. Expression levels of DKK1 peaked during early osteogenic differentiation (day 3). Concordantly, anti-DKK1 supplemented early (day 3 or before), but not later (day 7) during osteogenic differentiation positively regulated osteoblast formation. Finally, anti-DKK1 led to increased transcript abundance of the Wnt inhibitor SOST, potentially representing a compensatory cellular mechanism. In sum, DKK1 represents a targetable "molecular brake" on the osteogenic differentiation of human ASC. Moreover, release of this brake by neutralizing anti-DKK1 antibody treatment at least partially rescues the poor bone-forming efficacy of ASC

    Bone-forming perivascular cells: Cellular heterogeneity and use for tissue repair

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    : Mesenchymal progenitor cells are broadly distributed across perivascular niches-an observation conserved between species. One common histologic zone with a high frequency of mesenchymal progenitor cells within mammalian tissues is the tunica adventitia, the outer layer of blood vessel walls populated by cells with a fibroblastic morphology. The diversity and functions of (re)generative cells present in this outermost perivascular niche are under intense investigation; we have reviewed herein our current knowledge of adventitial cell potential with a somewhat narrow focus on bone formation. Antigens of interest to functionally segregate adventicytes are discussed, including CD10, CD107a, aldehyde dehydrogenase isoforms, and CD140a, among others. Purified adventicytes (such as CD10+ , CD107alow , and CD140a+ cells) have stronger osteogenic potential and promote bone formation in vivo. Recent bone tissue engineering applications of adventitial cells are also presented. A better understanding of perivascular progenitor cell subsets may represent a beneficial advance for future efforts in tissue repair and bioengineering

    Direct Measurements of the Branching Fractions for D0Ke+νeD^0 \to K^-e^+\nu_e and D0πe+νeD^0 \to \pi^-e^+\nu_e and Determinations of the Form Factors f+K(0)f_{+}^{K}(0) and f+π(0)f^{\pi}_{+}(0)

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    The absolute branching fractions for the decays D0Ke+νeD^0 \to K^-e ^+\nu_e and D0πe+νeD^0 \to \pi^-e^+\nu_e are determined using 7584±198±3417584\pm 198 \pm 341 singly tagged Dˉ0\bar D^0 sample from the data collected around 3.773 GeV with the BES-II detector at the BEPC. In the system recoiling against the singly tagged Dˉ0\bar D^0 meson, 104.0±10.9104.0\pm 10.9 events for D0Ke+νeD^0 \to K^-e ^+\nu_e and 9.0±3.69.0 \pm 3.6 events for D0πe+νeD^0 \to \pi^-e^+\nu_e decays are observed. Those yield the absolute branching fractions to be BF(D0Ke+νe)=(3.82±0.40±0.27)BF(D^0 \to K^-e^+\nu_e)=(3.82 \pm 0.40\pm 0.27)% and BF(D0πe+νe)=(0.33±0.13±0.03)BF(D^0 \to \pi^-e^+\nu_e)=(0.33 \pm 0.13\pm 0.03)%. The vector form factors are determined to be f+K(0)=0.78±0.04±0.03|f^K_+(0)| = 0.78 \pm 0.04 \pm 0.03 and f+π(0)=0.73±0.14±0.06|f^{\pi}_+(0)| = 0.73 \pm 0.14 \pm 0.06. The ratio of the two form factors is measured to be f+π(0)/f+K(0)=0.93±0.19±0.07|f^{\pi}_+(0)/f^K_+(0)|= 0.93 \pm 0.19 \pm 0.07.Comment: 6 pages, 5 figure

    Measurements of J/psi Decays into 2(pi+pi-)eta and 3(pi+pi-)eta

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    Based on a sample of 5.8X 10^7 J/psi events taken with the BESII detector, the branching fractions of J/psi--> 2(pi+pi-)eta and J/psi-->3(pi+pi-)eta are measured for the first time to be (2.26+-0.08+-0.27)X10^{-3} and (7.24+-0.96+-1.11)X10^{-4}, respectively.Comment: 11 pages, 6 figure

    BESII Detector Simulation

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    A Monte Carlo program based on Geant3 has been developed for BESII detector simulation. The organization of the program is outlined, and the digitization procedure for simulating the response of various sub-detectors is described. Comparisons with data show that the performance of the program is generally satisfactory.Comment: 17 pages, 14 figures, uses elsart.cls, to be submitted to NIM

    Search for the Lepton Flavor Violation Processes J/ψJ/\psi \to μτ\mu\tau and eτe\tau

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    The lepton flavor violation processes J/ψμτJ/\psi \to \mu\tau and eτe\tau are searched for using a sample of 5.8×107\times 10^7 J/ψJ/\psi events collected with the BESII detector. Zero and one candidate events, consistent with the estimated background, are observed in J/ψμτ,τeνˉeντJ/\psi \to \mu\tau, \tau\to e\bar\nu_e\nu_{\tau} and J/ψeτ,τμνˉμντJ/\psi\to e\tau, \tau\to\mu\bar\nu_{\mu}\nu_{\tau} decays, respectively. Upper limits on the branching ratios are determined to be Br(J/ψμτ)<2.0×106Br(J/\psi\to\mu\tau)<2.0 \times 10^{-6} and Br(J/ψeτ)<8.3×106Br(J/\psi \to e\tau) < 8.3 \times10^{-6} at the 90% confidence level (C.L.).Comment: 9 pages, 2 figure

    The σ\sigma pole in J/ψωπ+πJ/\psi \to \omega \pi^+ \pi^-

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    Using a sample of 58 million J/ψJ/\psi events recorded in the BESII detector, the decay J/ψωπ+πJ/\psi \to \omega \pi^+ \pi^- is studied. There are conspicuous ωf2(1270)\omega f_2(1270) and b1(1235)πb_1(1235)\pi signals. At low ππ\pi \pi mass, a large broad peak due to the σ\sigma is observed, and its pole position is determined to be (541±39)(541 \pm 39) - ii (252±42)(252 \pm 42) MeV from the mean of six analyses. The errors are dominated by the systematic errors.Comment: 15 pages, 6 figures, submitted to PL
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