39 research outputs found

    Character of frustration on magnetic correlation in doped Hubbard model

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    The magnetic correlation in the Hubbard model on a two-dimensional anisotropic triangular lattice is studied by using the determinant quantum Monte Carlo method. Around half filling, it is found that the increasing frustration t/tt'/t could change the wave vector of maximum spin correlation along (π,π\pi,\pi)\rightarrow(π,5π6\pi,\frac{5\pi}{6})\rightarrow(5π6,5π6\frac{5\pi}{6},\frac{5\pi}{6})\rightarrow (2π3,2π3\frac{2\pi}{3},\frac{2\pi}{3}), indicating the frustration's remarkable effect on the magnetism. In the studied filling region =1.0-1.3, the doping behaves like some kinds of {\it{frustration}}, which destroys the (π,π)(\pi,\pi) AFM correlation quickly and push the magnetic order to a wide range of the (2π3,2π3)(\frac{2\pi}{3},\frac{2\pi}{3}) 120120^{\circ} order when the t/tt'/t is large enough. Our non-perturbative calculations reveal a rich magnetic phase diagram over both the frustration and electron doping.Comment: 6 pages, 7 figure

    Prevalence, associated factors and outcomes of pressure injuries in adult intensive care unit patients: the DecubICUs study

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    Funder: European Society of Intensive Care Medicine; doi: http://dx.doi.org/10.13039/501100013347Funder: Flemish Society for Critical Care NursesAbstract: Purpose: Intensive care unit (ICU) patients are particularly susceptible to developing pressure injuries. Epidemiologic data is however unavailable. We aimed to provide an international picture of the extent of pressure injuries and factors associated with ICU-acquired pressure injuries in adult ICU patients. Methods: International 1-day point-prevalence study; follow-up for outcome assessment until hospital discharge (maximum 12 weeks). Factors associated with ICU-acquired pressure injury and hospital mortality were assessed by generalised linear mixed-effects regression analysis. Results: Data from 13,254 patients in 1117 ICUs (90 countries) revealed 6747 pressure injuries; 3997 (59.2%) were ICU-acquired. Overall prevalence was 26.6% (95% confidence interval [CI] 25.9–27.3). ICU-acquired prevalence was 16.2% (95% CI 15.6–16.8). Sacrum (37%) and heels (19.5%) were most affected. Factors independently associated with ICU-acquired pressure injuries were older age, male sex, being underweight, emergency surgery, higher Simplified Acute Physiology Score II, Braden score 3 days, comorbidities (chronic obstructive pulmonary disease, immunodeficiency), organ support (renal replacement, mechanical ventilation on ICU admission), and being in a low or lower-middle income-economy. Gradually increasing associations with mortality were identified for increasing severity of pressure injury: stage I (odds ratio [OR] 1.5; 95% CI 1.2–1.8), stage II (OR 1.6; 95% CI 1.4–1.9), and stage III or worse (OR 2.8; 95% CI 2.3–3.3). Conclusion: Pressure injuries are common in adult ICU patients. ICU-acquired pressure injuries are associated with mainly intrinsic factors and mortality. Optimal care standards, increased awareness, appropriate resource allocation, and further research into optimal prevention are pivotal to tackle this important patient safety threat

    A Moving Target Tracking Framework Based on a Set and Its Topological Space

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    Moving target tracking is a technology that matches frames and images based on target characteristics. This technology is widely utilized in intelligent transportation, logistics transportation, public security, sports event broadcasting, and other fields. Existing research focuses primarily on improving target detection and tracking algorithms to improve target retrieval and tracking efficiency. However, the majority of studies focus on global and full-range retrieval. More importantly, in large video scenes with multiple camera collaborations, these methods rarely consider the efficiency of target retrieval and tracking. Based on relevant theories and methods of video GIS, set theory, and topology, in this paper, a set and its topology space covering road networks, cameras, videos, and key frames were constructed. Additionally, the positioning, tracking, and track representation of a moving target based on the set and its topology space were solved. Compared to the feature vector algorithm, video summarization and Meanshift algorithm, the experimental findings reveal that the target retrieval performance, algorithm stability, and robustness are improved

    Highly Sensitive Dual Parameter Sensor Based on a Hybrid Structure with Multimode Interferometer and Fiber Bragg Grating Fabricated by Femtosecond Laser

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    A hybrid sensing configuration for simultaneous measurement of strain and temperature based on fiber Bragg grating (FBG) written in an offset multimode fiber (MMF) interferometer using femtosecond laser pulse is proposed and demonstrated. A Mach–Zehnder interferometer is formed by splicing a section of MMF between two single-mode fibers (SMFs) and a high interference fringe of up to 15 dB is achieved. The sensing experimental results show a strain sensitivity of −1.17 pm/με and 0.6498 pm/με for the dip of MZI and Bragg peak, while a temperature sensitivity of 42.84 pm/°C and 19.96 pm/°C is measured. Furthermore, the matrix analysis has found that the strain and temperature resolution of the sensor are as high as ±12.36 με and ±0.35 °C, respectively. In addition, the sensor has merits of simple fabrication, good spectral quality, and high resolution, which shows attractive potential applications in dual-parameter sensing

    Shape-memory actuation in aligned zirconia nanofibers for artificial muscle applications at elevated temperatures

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    Artificial muscle is one of the key technologies to accelerate the development of robotics, automation, and artificial-intelligence-embedded systems. This work aims to develop shape-memory ceramic (SMC) nanofiber-based coiled yarns for artificial muscle applications at elevated temperatures. Highly aligned SMC nanofiber (zirconia-based) yarns and springs have been successfully fabricated by electrospinning. The microstructure and tensile properties of the SMC nanofibers and the shape-memory actuation performance of the SMC yarns/springs have been characterized. A significant shape-memory effect with a recoverable strain of up to ∼5% and short recovery time (0.16 s) has been demonstrated in the SMC yarns at actuation temperatures of 328-388 °C. The SMC springs can lift up to 87 times their own weight when heated by a Bunsen burner, and the stroke is 3.9 mm. The SMC yarns/springs exhibit an output stress of 14.5-22.6 MPa, a work density of 15-20 kJ//m3, and a tensile strength of 100-200 MPa, which are much higher than those of human muscles and some other polymer-based artificial muscles. Benefiting from the advantages of large output stress, high tensile strength, high actuation temperatures, and fast response, the SMC nanofiber-based yarns/springs have a great potential to be used as artificial muscles at elevated temperatures.The authors would like to acknowledge the funding support under project agreements PA 9011102294 and 9011102296. The authors would like to acknowledge Prof. Zhong Chen from the School of Materials Science and Engineering in NTU for his support in tensile testing

    Fabrication of a Plasmonic Heterojunction for Degradation of Oxytetracycline Hydrochloride and Removal of Cr(VI) from Water

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    A novel Ag/Ag2CO3/BiVO4 plasmonic photocatalyst was successfully prepared by depositing Ag nanoparticles on the surface of Ag2CO3/BiVO4 through the photoreduction reaction. Due to the existence of this novel heterojunction photocatalyst structure, not only can it prevent the photogenerated charge recombination, but the unique properties of Ag also have a great advantage in the absorption of light. The Ag/Ag2CO3/BiVO4 photocatalyst showed good catalytic performance in the degradation of oxytetracycline hydrochloride (OTH) and removal of Cr6+, and the degradation rate of OTH reached 98.0% after 150 min of illumination. The successful preparation of Ag/Ag2CO3/BiVO4 was confirmed by a series of characterization methods, and the importance of •OH and h+ radicals in the degradation of OTH was demonstrated. In addition, the photocatalytic mechanism of Ag/Ag2CO3/BiVO4 photocatalyst was systematically studied in terms of degradation of OTH and reduction of Cr6+. This study is of great importance for the development of novel plasmonic heterojunction photocatalysts and to meet future environmental requirements
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