A widely used iterative technique named the Method of Ordered Multiple Interactions is given for calculat-ing the Gaussian-like beam scattering from a time-varying sea surface with the Pierson-Moskowitz (P-M) spectrum...A widely used iterative technique named the Method of Ordered Multiple Interactions is given for calculat-ing the Gaussian-like beam scattering from a time-varying sea surface with the Pierson-Moskowitz (P-M) spectrum. Thisis done by solving the magnetic field integral equation for the current induced on an infinite rough surface. Following thediscretization of the integral equation, the unknown currents can be determined more rapidly with the LU decomposition.Numerical results are presented with emphasis on the electromagnetic backscattering at low grazing angle incidence. Itis shown that the backscattering cross section is proportional to the nearly fourth power of the grazing angle for thebackscattering cross section with a different beam waist, surface length, and velocity of the wind are展开更多
Plant stress caused by exposure to magnetic fields （MF） induces modifications at molecular level, particularly in DNA synthesis, structure, and function. The objective of this study was to determine the effect of va...Plant stress caused by exposure to magnetic fields （MF） induces modifications at molecular level, particularly in DNA synthesis, structure, and function. The objective of this study was to determine the effect of various doses of non-ionizing radiation of magnetic field on date palm （Phoenix dactylifera L.） based on DNA content. Date palm seedlings （cv. Khalas） established for 2 weeks on filter paper were subjected to static magnetic field and alternating magnetic field. Static magnetic fields （SMF） were applied at 10, 50 and 100 mT for 30, 60, 120, 180, 240 and 360 min; while alternating magnetic field applied by magnetic resonance imaging （MRI） at 1500 mT for 1, 5, 10 and 15 min. The seedlings were grown in potting soil following exposure for 4 weeks after which DNA was extracted from leaves and its content was determined. Generally, the exposure to magnetic field caused reduction in the content of DNA. The lowest exposure time tested, 30 rain, was sufficient to induce reduction in DNA content. This was true even at the lowest intensity, 10 mT. This dosage caused the DNA content to decrease from 49 ~tg/g to 45 pg/g. Further, increase of the exposure duration to 60 min caused significant reduction in the DNA content, 36 μg/g. At intensities higher than 10 mT, DNA content decreased significantly even at the shortest exposure of 30 min. At 50 and 100 mT, significant decrease in DNA content was also noticed in response to 30 min exposure; whereas the level of DNA increased after 1 min of MRI exposure to 52 ~g/g, then decreased after 5 min to 46 ~g/g. However, longer durations caused no further decrease in the DNA content. These observations indicate that magnetic fields interact with DNA processes, probably by inhibiting synthesis or stimulating degradation of DNA. This response merits further exploration as a mutational agent for date palm genetic manipulation.展开更多
A series of Cr/SmCo/Cr films with high Sm concentration(37.7at%) were prepared by magnetron sputtering.Effects of SmCo thickness,annealing temperature,and annealing time on magnetic properties and crystal structure we...A series of Cr/SmCo/Cr films with high Sm concentration(37.7at%) were prepared by magnetron sputtering.Effects of SmCo thickness,annealing temperature,and annealing time on magnetic properties and crystal structure were carefully studied.Results show that crystallization degree and phase transition in the films can be controlled by the SmCo thickness and optimized by properly increasing the annealing temperature and extending the annealing time.Finally,a SmCo film with high magnetic properties and low MEI was constructed.展开更多
Invasive species and habitat degradation are the main reasons for freshwater biodiversity loss. Reports on the habitat degradation and invasion ecology of Red Swamp crayfish(Procambarus clarkii) are few, although it i...Invasive species and habitat degradation are the main reasons for freshwater biodiversity loss. Reports on the habitat degradation and invasion ecology of Red Swamp crayfish(Procambarus clarkii) are few, although it is one of the most devastating invasive species in freshwater ecosystems. Based on a three-year investigation during 2017-2019 in West Dongting Lake, this study used Principal Component Analysis(PCA), Generalized Linear Model(GLM) and Bayesian model to analyze the relationships of P. clarkii stocks and environment factors in natural and modified wetlands. The results showed that the abundance of P. clarkii was positively correlated with total nitrogen, total phosphorus, water temperature, pH, water depth, and water transparency;while it was negatively correlated with dissolved oxygen and redox potential. The difference between P. clarkii stocks in natural and modified wetlands was nonsignificant. The P. clarkii stock decreased yearly, as levels in both 2018 and 2019 were significantly lower than in 2017. We concluded that inter-annual variation of the hydrological regime plays an important role in P. clarkii dynamics, and thus it is of great importance to ensure that the water level and flow velocity in summer to control the invasive P. clarkii.展开更多
文摘A widely used iterative technique named the Method of Ordered Multiple Interactions is given for calculat-ing the Gaussian-like beam scattering from a time-varying sea surface with the Pierson-Moskowitz (P-M) spectrum. Thisis done by solving the magnetic field integral equation for the current induced on an infinite rough surface. Following thediscretization of the integral equation, the unknown currents can be determined more rapidly with the LU decomposition.Numerical results are presented with emphasis on the electromagnetic backscattering at low grazing angle incidence. Itis shown that the backscattering cross section is proportional to the nearly fourth power of the grazing angle for thebackscattering cross section with a different beam waist, surface length, and velocity of the wind are
文摘Plant stress caused by exposure to magnetic fields （MF） induces modifications at molecular level, particularly in DNA synthesis, structure, and function. The objective of this study was to determine the effect of various doses of non-ionizing radiation of magnetic field on date palm （Phoenix dactylifera L.） based on DNA content. Date palm seedlings （cv. Khalas） established for 2 weeks on filter paper were subjected to static magnetic field and alternating magnetic field. Static magnetic fields （SMF） were applied at 10, 50 and 100 mT for 30, 60, 120, 180, 240 and 360 min; while alternating magnetic field applied by magnetic resonance imaging （MRI） at 1500 mT for 1, 5, 10 and 15 min. The seedlings were grown in potting soil following exposure for 4 weeks after which DNA was extracted from leaves and its content was determined. Generally, the exposure to magnetic field caused reduction in the content of DNA. The lowest exposure time tested, 30 rain, was sufficient to induce reduction in DNA content. This was true even at the lowest intensity, 10 mT. This dosage caused the DNA content to decrease from 49 ~tg/g to 45 pg/g. Further, increase of the exposure duration to 60 min caused significant reduction in the DNA content, 36 μg/g. At intensities higher than 10 mT, DNA content decreased significantly even at the shortest exposure of 30 min. At 50 and 100 mT, significant decrease in DNA content was also noticed in response to 30 min exposure; whereas the level of DNA increased after 1 min of MRI exposure to 52 ~g/g, then decreased after 5 min to 46 ~g/g. However, longer durations caused no further decrease in the DNA content. These observations indicate that magnetic fields interact with DNA processes, probably by inhibiting synthesis or stimulating degradation of DNA. This response merits further exploration as a mutational agent for date palm genetic manipulation.
基金supported by the National Natural Science Foundation of China(Grant Nos.50901007 and 11174020)the Postdoctoral Science Foundation of China(Grant No.201003049)+2 种基金the Foundation of Key Laboratory for Advanced Materials Processing Technology,Ministry of Education,China(Grant No.2010001)the Fundamental Research Funds for the Central Universitiesthe New Teacher Foundation of Ministry of Education(Grant No.200800081030)
文摘A series of Cr/SmCo/Cr films with high Sm concentration(37.7at%) were prepared by magnetron sputtering.Effects of SmCo thickness,annealing temperature,and annealing time on magnetic properties and crystal structure were carefully studied.Results show that crystallization degree and phase transition in the films can be controlled by the SmCo thickness and optimized by properly increasing the annealing temperature and extending the annealing time.Finally,a SmCo film with high magnetic properties and low MEI was constructed.
基金The Fundamental Research Funds for the Central Universities (2017ZY15)The National Key Research and Development Program of China (2017YFC0405303)。
文摘Invasive species and habitat degradation are the main reasons for freshwater biodiversity loss. Reports on the habitat degradation and invasion ecology of Red Swamp crayfish(Procambarus clarkii) are few, although it is one of the most devastating invasive species in freshwater ecosystems. Based on a three-year investigation during 2017-2019 in West Dongting Lake, this study used Principal Component Analysis(PCA), Generalized Linear Model(GLM) and Bayesian model to analyze the relationships of P. clarkii stocks and environment factors in natural and modified wetlands. The results showed that the abundance of P. clarkii was positively correlated with total nitrogen, total phosphorus, water temperature, pH, water depth, and water transparency;while it was negatively correlated with dissolved oxygen and redox potential. The difference between P. clarkii stocks in natural and modified wetlands was nonsignificant. The P. clarkii stock decreased yearly, as levels in both 2018 and 2019 were significantly lower than in 2017. We concluded that inter-annual variation of the hydrological regime plays an important role in P. clarkii dynamics, and thus it is of great importance to ensure that the water level and flow velocity in summer to control the invasive P. clarkii.
