36,476 research outputs found

    An Efficient Algorithm by Kurtosis Maximization in Reference-Based Framework

    Get PDF
    This paper deals with the optimization of kurtosis for complex-valued signals in the independent component analysis (ICA) framework, where source signals are linearly and instantaneously mixed. Inspired by the recently proposed reference-based contrast schemes, a similar contrast function is put forward, based on which a new fast fixed-point (FastICA) algorithm is proposed. The new optimization method is similar in spirit to the former classical kurtosis-based FastICA algorithm but differs in the fact that it is much more efficient than the latter in terms of computational speed, which is significantly striking with large number of samples. The performance of this new algorithm is confirmed through computer simulations

    Numerical simulation of solid tumor blood perfusion and drug delivery during the “vascular normalization window” with antiangiogenic therapy

    Get PDF
    This Article is provided by the Brunel Open Access Publishing Fund - Copyright @ 2011 Hindawi PublishingTo investigate the influence of vascular normalization on solid tumor blood perfusion and drug delivery, we used the generated blood vessel network for simulations. Considering the hemodynamic parameters changing after antiangiogenic therapies, the results show that the interstitial fluid pressure (IFP) in tumor tissue domain decreases while the pressure gradient increases during the normalization window. The decreased IFP results in more efficient delivery of conventional drugs to the targeted cancer cells. The outcome of therapies will improve if the antiangiogenic therapies and conventional therapies are carefully scheduled

    Investigation and Countermeasures on the Current Situation of Foreign-related Nursing Talents and Talents Demand in Shanghai Medical Institutions

    Get PDF
    Objective: Understand the needs of medical institutions in Shanghai for foreign-related nursing talents and provide a basis for training nursing talents in schools. Method: Self-designed questionnaires, according to the current situation of foreign-related nursing staff, demands of foreign-related nursing staff and types of foreign-related nursing, relevant objective data were collected through on-site visits. Results: Foreign-related nursing personnel of comprehensive hospitals accounted for 10.1%; Foreign capital and sino-foreign joint venture medical institutions account for 26.7%; Foreign nurses stations account for 1%; The foreign-related nursing staff mainly recruits staff with working experience in the medical institutions and the unit itself, and is supplemented by college graduates recruiting new graduates; Foreign nursing staff evaluation is fully qualified for 15.8%; 52.6% of medical institutions are not limited to foreign-related nursing professionals; The requirements of ‘communicative competence, medical knowledge literacy and language proficiency’ rank in the top 3. Conclusion: The needs of foreign nursing professionals are high, demand is high, and post competency needs to be improved, the ability to communicate, humanistic, and English is the focus of consideration.     Keywords: medical institutions, foreign-related nursing, talent deman

    The Impact of COVID-19 on the Ride-Sharing Industry and Its Recovery: Causal Evidence from China

    Get PDF
    The COVID-19 pandemic has brought unprecedented disruptions to many industries, and the transportation industry is among the most disrupted ones. We seek to address, in the context of a ride-sharing platform, the response of drivers to the pandemic and the post-pandemic recovery. We collected comprehensive trip data from one of the leading ride-sharing companies in China from September 2019 to August 2020, which cover pre-, during-, and post-pandemic phases in three major Chinese cities, and investigate the causal effect of the COVID-19 pandemic on driver behavior. We find that drivers only slightly reduced their shift decision in response to increased COVID-19 cases, likely because they have to make a living from providing ride-sharing services. Nevertheless, conditional on working, drivers exhibit strong risk aversion: As the number of new cases increases, drivers strategically adjust the scope of search for passengers, complete fewer trips, and as a result, make lower daily earnings. Finally, our heterogeneity analyses indicate that the effects appear to vary both across drivers and over time, with generally stronger effects on drivers who are older, more experienced, more active before the pandemic, and with higher status within the firm. Our findings have strong policy implications: These drivers tend to contribute more to the focal company, and also rely more on providing ride-sharing services to make a living. Therefore, they should be prioritized in stimulus plans offered by the government or the ride-sharing company

    Generalized r-matrix structure and algebro-geometric solution for integrable systems

    Full text link
    The purpose of this paper is to construct a generalized r-matrix structure of finite dimensional systems and an approach to obtain the algebro-geometric solutions of integrable nonlinear evolution equations (NLEEs). Our starting point is a generalized Lax matrix instead of usual Lax pair. The generalized r-matrix structure and Hamiltonian functions are presented on the basis of fundamental Poisson bracket. It can be clearly seen that various nonlinear constrained (c-) and restricted (r-) systems, such as the c-AKNS, c-MKdV, c-Toda, r-Toda, c-Levi, etc, are derived from the reduction of this structure. All these nonlinear systems have {\it r}-matrices, and are completely integrable in Liouville's sense. Furthermore, our generalized structure is developed to become an approach to obtain the algebro-geometric solutions of integrable NLEEs. Finally, the two typical examples are considered to illustrate this approach: the infinite or periodic Toda lattice equation and the AKNS equation with the condition of decay at infinity or periodic boundary.Comment: 41 pages, 0 figure

    Calibration of LAMOST Stellar Surface Gravities Using the Kepler Asteroseismic Data

    Full text link
    Asteroseismology is a powerful tool to precisely determine the evolutionary status and fundamental properties of stars. With the unprecedented precision and nearly continuous photometric data acquired by the NASA Kepler mission, parameters of more than 104^4 stars have been determined nearly consistently. However, most studies still use photometric effective temperatures (Teff) and metallicities ([Fe/H]) as inputs, which are not sufficiently accurate as suggested by previous studies. We adopted the spectroscopic Teff and [Fe/H] values based on the LAMOST low-resolution spectra (R~1,800), and combined them with the global oscillation parameters to derive the physical parameters of a large sample of stars. Clear trends were found between {\Delta}logg(LAMOST - seismic) and spectroscopic Teff as well as logg, which may result in an overestimation of up to 0.5 dex for the logg of giants in the LAMOST catalog. We established empirical calibration relations for the logg values of dwarfs and giants. These results can be used for determining the precise distances to these stars based on their spectroscopic parameters.Comment: 22 pages, 13 figures and 3 tables, accepted for publication in Astronomical Journal. Table 3 is available at http://lwang.info/research/kepler_lamost
    corecore