11,075 research outputs found
Solutions of the Yang-Mills-Higgs equations in 2+1 dimensional anti-de Sitter space-time
The solutions of the Bogomolny equation in anti-de Sitter space-time are
obtained by using Darboux transformations with both constant spectral
parameters and variable "spectral parameters". These solutions give the
Yang-Mills-Higgs fields in anti-de Sitter space-time. Some examples in SU(2)
case are considered and qualitative asymptotic behaviors of the solutions as t
tends to infinity are discussed in detail.Comment: LaTeX, 18 pages, 11 PS figure
Intermediate-Mass Black Holes in Globular Clusters
There have been reports of possible detections of intermediate-mass black
holes (IMBHs) in globular clusters (GCs). Empirically, there exists a tight
correlation between the central supermassive black hole (SMBH) mass and the
mean velocity dispersion of elliptical galaxies, "pseudobulges" and classical
bulges of spiral galaxies. We explore such a possible correlation for IMBHs in
spherical GCs. In our model of self-similar general polytropic quasi-static
dynamic evolution of GCs, a criterion of forming an IMBH is proposed. The key
result is M(BH) = L o^1/(1-n) where M(BH) is the IMBH mass, o is the GC mean
stellar velocity, L is a coefficient, and 2/3 < n < 1
Forecast on Energy Demand of Road Transportation in China
AbstractTo some extent, there are some uncertainties factors in forecasting energy demand of road transportation. Scientific forecasting China's energy demand of road transportation is a key for make long-term development plans of the nation's road transportation, and relevant policies of environmental protection and energy-saving. Basing on the energy demand of China's road transportation, considering the factors average fuel consumption of singleautomobile and the workload of road transportation, the paper does a comprehensive forecasting for China's energy demand of transportation in the future. The result is that in 2030, the energy demand of road transportation will amount to 250 million tons, which is 1.4 times that of 2020, and 2.3 times that of 2010. The significant increase of energy demand will inevitably bring great pressure to resources of energy and environmental protection, so the implementation of scientific development concept, saving resources and protecting the environment and adopting sustainable development policy will be the objective requirements for highway transportation development of China in the future
Artificial Intelligence, CEO Turnover, and Directional Change in Firm Innovation
We examine the role of artificial intelligence (AI) in facilitating a change in innovation directions after a leadership change. Using patent data for firms that have gone through a CEO turnover, we find that firms with greater AI investment are more successful in changing their innovation directions. The effect of AI is driven principally by the continued development of innovation in areas that are modestly different from the past. Further analyses show that this effect is likely due to firms with AI investment that can enable strategic change in cultivating culture of exploring frontiers in innovation and managing R&D. A new CEO can direct more resources to the acquisition of employees with greater technological capabilities such as AI skills to facilitate the innovation change. Overall, our study sheds light on the value of AI in fostering the change in innovation directions during uncertain and turbulent times
An Information Model for Geographic Greedy Forwarding in Wireless Ad-Hoc Sensor Networks
In wireless ad-hoc sensor networks, an important issue often faced in geographic greedy forwarding routing is the "local minimum phenomenon" which is caused by deployment holes and blocks the forwarding process. In this paper, we provide a new information model for the geographic greedy forwarding routing that only forwards the packet within the so-called request zone. Under this new information model, the hole and its affected area are identified easily and quickly in an unsafe area with a labeling process. The greedy forwarding will be blocked if and only if a node inside the unsafe area is used. Due to the shape of the request zone, an unsafe area can be estimated as a rectangular region in the local view of unsafe nodes. With such estimate information, the new routing method proposed in this paper will avoid blocking by holes and achieve better performance in routing time while the cost of information construction is greatly reduced compared with the best results known to date.Department of ComputingRefereed conference pape
Capacitance Characteristics of Pinus densata, Pinus tabuliformis, Pinus yunnanensis and the hybrids Pinus tabuliformis × Pinus Yunnanensis
We employed capacitance to evaluate the kinship and interspecific variation of homoploid hybrid conifer Pinus densata, P. tabuliformis, P. yunnanensis and artificial hybrids of P. tabuliformis (maternal parent) and P. yunnanensis (paternal parent) which were cultivated and selected in the common garden experiment. By measuring capacitance spectra under different voltage frequencies, we could differentiate different germplasms based on the electrical response. We aims to demonstrate that P. densata as the hybrid of P. tabuliformis and P. yunnanensis based on the capacitance values of the species, and to provide new evidence to the previously known biological evidence, as well as and the parental effect on the hybrids. Our results revealed that capacitance values between the species are significantly different in the spectra where P. yunnanensis positioned at the lowest and P. densata was much higher than all other species, indicating that P. densata had possessed a great capacity to store electrical energy. The capacitance spectra of P. densata and the artificial hybrid are not similar, which rejected our hypothesis. Both of the capacitance values of P. densata and the hybrids were closer to P. tabuliformis than to P. yunnanensis, which shows that the maternal influence was stronger than the paternal influence. Correlation analysis on the relationship between capacitance and fitnessrelated characteristics showed that capacitance is negatively correlated to mortality rate, and positively correlated with second-year survival rate. High capacitance values of P. densata and some of the hybrids reveal their superior adaptability to harsh environment in the Tibet Plateau. We concluded that capacitance as a new indicator for plant fitness and evolution evidence of homoploid hybrid conifers
The role of joint distraction in the treatment of knee osteoarthritis: a systematic review and quantitative analysis
Introduction: Knee osteoarthritis is a major cause of pain and disability for which joint distraction is a potential treatment to delay the need for knee arthroplasty. This systematic review aims to assess the short- and long-term clinical and structural outcomes following knee joint distraction (KJD). Methods: MEDLINE, EMBASE, Scopus and Web of Science databases were searched from the date of inception to 26th June 2019. Clinical studies investigating joint distraction for knee osteoarthritis with outcomes including ∆WOMAC index, ∆VAS pain score and ∆joint space width were included. The review protocol was registered with the International Prospective Register of Systematic Reviews (PROSPERO) – CRD42018087032. Results: Nine studies comprising a total of 507 patients were included. There were four randomised controlled trials (RCTs), five open prospective cohort studies and one case series. Overall, there were significant improvements in WOMAC index, VAS pain score and joint space width following KJD, which persisted up till nine years. KJD also demonstrated comparable clinical outcomes with HTO and TKA. Conclusion: There is moderate quality evidence supporting the beneficial outcomes of joint distraction for knee osteoarthritis. Larger RCTs with longer follow-up (>1 year) are necessary to establish the true effect size of this procedure
Joint distraction for knee osteoarthritis: protocol for a systematic review and meta-analysis
Background Osteoarthritis is a degenerative joint disease that is highly prevalent worldwide. Knee osteoarthritis is the most common form of osteoarthritis and is a major cause of pain and disability. However, there remains a lack of treatments available that have demonstrated effectiveness in stopping or reversing the degenerative process. Joint distraction has emerged as a viable alternative in the treatment of knee osteoarthritis to delay the need for knee arthroplasty. Methods An electronic search will be conducted on MEDLINE, EMBASE, Web of Science, CINAHL, Cochrane and EBSCO databases. Clinical studies investigating joint distraction for knee osteoarthritis, which reported clinical or structural outcomes including ∆WOMAC index, ∆VAS pain score and ∆joint space width will be included. Risk of bias will be assessed using the Newcastle-Ottawa Scale for observational studies and Cochrane Collaboration tool for randomised controlled trials. Quality of studies will be assessed using the modified Coleman methodology score. Discussion This systematic review will summarise the short- and long-term clinical and structural outcomes following joint distraction for knee osteoarthritis. The findings from this review will establish the quality of currently available evidence, which will determine the need for further studies to establish the true effect size of this procedure
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