338 research outputs found

    Uniform Asymptotics of Orthogonal Polynomials Arising from Coherent States

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    In this paper, we study a family of orthogonal polynomials {ϕn(z)}\{\phi_n(z)\} arising from nonlinear coherent states in quantum optics. Based on the three-term recurrence relation only, we obtain a uniform asymptotic expansion of ϕn(z)\phi_n(z) as the polynomial degree nn tends to infinity. Our asymptotic results suggest that the weight function associated with the polynomials has an unusual singularity, which has never appeared for orthogonal polynomials in the Askey scheme. Our main technique is the Wang and Wong's difference equation method. In addition, the limiting zero distribution of the polynomials ϕn(z)\phi_n(z) is provided

    The Effects of Corporate Governance on the Innovation Performance of Chinese SMEs

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    We investigate the degree to which corporate governance and ownership affects the innovation performance of firms in China with a particular focus on privately owned small and medium enterprises (SMEs). We hypothesize that (1) board-related governance measures will enhance innovation because they improve monitoring and provide access to necessary resources; (2) ownership concentration initially facilitates innovation because large shareholders are more likely to commit to the long-term nature of innovation, and have the incentive to monitor managers whose time horizon may be shorter; however we argue that these effects weaken as large shareholders becomes entrenched at higher levels of concentration; and (3) hiring an external CEO will enhance innovation both by ensuring professional management of the company, and by alleviating the entrenchment possibilities associated with large shareholders. These hypotheses are tested using a unique sample of 370 mostly private and relatively small Chinese firms in Zhejiang province, for the period 2004 to 2006. The results suggest that for this sample, corporate governance and ownership affect innovation activity when measured by patenting activity, but not when measured by new product sales

    Fault Detection and Diagnosis for Gas Turbines Based on a Kernelized Information Entropy Model

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    Gas turbines are considered as one kind of the most important devices in power engineering and have been widely used in power generation, airplanes, and naval ships and also in oil drilling platforms. However, they are monitored without man on duty in the most cases. It is highly desirable to develop techniques and systems to remotely monitor their conditions and analyze their faults. In this work, we introduce a remote system for online condition monitoring and fault diagnosis of gas turbine on offshore oil well drilling platforms based on a kernelized information entropy model. Shannon information entropy is generalized for measuring the uniformity of exhaust temperatures, which reflect the overall states of the gas paths of gas turbine. In addition, we also extend the entropy to compute the information quantity of features in kernel spaces, which help to select the informative features for a certain recognition task. Finally, we introduce the information entropy based decision tree algorithm to extract rules from fault samples. The experiments on some real-world data show the effectiveness of the proposed algorithms

    Patterning of ventral telencephalon requires positive function of Gli transcription factors

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    AbstractThe ability of neuroepithelial cells to generate a diverse array of neurons is influenced by locally secreted signals. In the spinal cord, Sonic Hedgehog (Shh) is known to induce distinct cell fates in a concentration-dependent manner by regulating the activities of the three Gli transcription factors in neural precursors. However, whether Gli-mediated Shh signaling is also required to induce different cell types in the ventral telencephalon has been controversial. In particular, loss of Shh has little effect on dorsoventral patterning of the telencephalon when Gli3 is also removed. Furthermore, no ventral telencephalic phenotypes have been found in individual Gli mutants. To address this issue, we first characterized Shh-responding ventral telencephalic progenitors between E9.5 and E12.5 and found that they produce neurons migrating to different layers of the cortex. We also discovered a loss of Nkx2.1 and Nkx6.2 expression in two subgroups of progenitors in embryos lacking major Gli activators. Finally, we analyzed the telencephalic phenotypes of embryos lacking all Gli genes and found that the ventral telencephalon was highly disorganized with intermingling of distinct neuronal cell types. Together, these studies unravel a role for Gli transcription factors in mediating Shh signaling to control specification, differentiation and positioning of ventral telencephalic neurons

    Wi-Closure: Reliable and Efficient Search of Inter-robot Loop Closures Using Wireless Sensing

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    In this paper we propose a novel algorithm, Wi-Closure, to improve computational efficiency and robustness of loop closure detection in multi-robot SLAM. Our approach decreases the computational overhead of classical approaches by pruning the search space of potential loop closures, prior to evaluation by a typical multi-robot SLAM pipeline. Wi-Closure achieves this by identifying candidates that are spatially close to each other by using sensing over the wireless communication signal between robots, even when they are operating in non-line-of-sight or in remote areas of the environment from one another. We demonstrate the validity of our approach in simulation and hardware experiments. Our results show that using Wi-closure greatly reduces computation time, by 54% in simulation and by 77% in hardware compared, with a multi-robot SLAM baseline. Importantly, this is achieved without sacrificing accuracy. Using Wi-Closure reduces absolute trajectory estimation error by 99% in simulation and 89.2% in hardware experiments. This improvement is due in part to Wi-Closure's ability to avoid catastrophic optimization failure that typically occurs with classical approaches in challenging repetitive environments.Comment: 6 pages without reference

    WSR: A WiFi Sensor for Collaborative Robotics

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    In this paper we derive a new capability for robots to measure relative direction, or Angle-of-Arrival (AOA), to other robots operating in non-line-of-sight and unmapped environments with occlusions, without requiring external infrastructure. We do so by capturing all of the paths that a WiFi signal traverses as it travels from a transmitting to a receiving robot, which we term an AOA profile. The key intuition is to "emulate antenna arrays in the air" as the robots move in 3D space, a method akin to Synthetic Aperture Radar (SAR). The main contributions include development of i) a framework to accommodate arbitrary 3D trajectories, as well as continuous mobility all robots, while computing AOA profiles and ii) an accompanying analysis that provides a lower bound on variance of AOA estimation as a function of robot trajectory geometry based on the Cramer Rao Bound. This is a critical distinction with previous work on SAR that restricts robot mobility to prescribed motion patterns, does not generalize to 3D space, and/or requires transmitting robots to be static during data acquisition periods. Our method results in more accurate AOA profiles and thus better AOA estimation, and formally characterizes this observation as the informativeness of the trajectory; a computable quantity for which we derive a closed form. All theoretical developments are substantiated by extensive simulation and hardware experiments. We also show that our formulation can be used with an off-the-shelf trajectory estimation sensor. Finally, we demonstrate the performance of our system on a multi-robot dynamic rendezvous task.Comment: 28 pages, 25 figures, *co-primary author

    What is needed by parents of constipated infants and toddlers: A cross-sectional study in China

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    BackgroundChildhood functional constipation is a worldwide problem that affects the intestinal function of children and the quality of life of their families. Treatment and management of the disease need to be carried out at home by parents. Assessment of caregiving needs is an important link in planning and implementing the intervention. This study aimed to assess the caregiving needs of parents of FC infants and toddlers.MethodsThe researchers recruited convenience samples of parents from an outpatient pediatric constipation clinic of a children's medical center. Totally 211 fathers/mothers were recruited. Nursing needs were measured by a questionnaire, and associations between nursing needs and potential factors were examined using multiple regression analysis.ResultsThe vast majority of participants (88.7%) expressed the need of receiving support from professionals, and only 44 (20.85%) had obtained help from medical staff. The needs of parents mainly include information needs, health needs, psychological needs, and social needs. Of all the needs, the highest score was for information needs (3.87 ± 0.69), followed by the dimension of health needs (3.74 ± 0.82). Results showed statistically significant differences in parental education, place of residence, age of children, duration of FC, defecation frequency, difficulty of defecation, and stool traits in nursing needs (p < 0.05). The regression model explained 64.2% of the variance of nursing needs.ConclusionsInformation needs were the major concern for parents, and the unmet needs of parents should be addressed during treatment and care. When developing care plans and providing health education, it should be adjusted according to the specific conditions of the child and parents to improve the compliance of the parents with treatment and care

    Construction of sterile system of Buchloe dactyloides (Nutt.) Engelm.

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    The stems of male and female strains of Bison grass (Buchloe dactyloides (Nutt.) Engelm.) were taken as explants, and 1 / 2MS and MS medium were used, and different concentrations of NAA, KT and 6-BA were added to study the rapid propagation technology of ferison grass. Results indicated that 75% alcohol was treated for 30s with another 0.1 g ꞏL-1The disinfection effect of mercury solution for 12 min; The MS + 1.5 mg ꞏL-1 NAA + 0.4 mg ꞏL-1 KT female strain showed the best induction effect, The MS + 1.5 mg ꞏL-1 NAA + 0.6 mg ꞏL-1 KT male strain had the best induction effect; 1 / 2 MS + 2 mg + L-1 NAA + 1.5 mg ꞏL-1 6-BA the female and male strains had the best proliferation effect; The highest number of roots and root root rate of 1 / 2 MS + 1.5 mg ꞏL-1 female and male NAA strains were combined
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