Broadband wireless channels are often time dispersive and become strongly frequency selective in delay spread domain. Commonly, these channels are composed of a few dominant coefficients and a large part of coefficien...Broadband wireless channels are often time dispersive and become strongly frequency selective in delay spread domain. Commonly, these channels are composed of a few dominant coefficients and a large part of coefficients are approximately zero or under noise floor. To exploit sparsity of multi-path channels (MPCs), there are various methods have been proposed. They are, namely, greedy algorithms, iterative algorithms, and convex program. The former two algorithms are easy to be implemented but not stable;on the other hand, the last method is stable but difficult to be implemented as practical channel estimation problems be-cause of computational complexity. In this paper, we introduce a novel channel estimation strategy using smooth L0 (SL0) algorithm which combines stable and low complexity. Computer simulations confirm the effectiveness of the introduced algorithm. We also give various simulations to verify the sensing training signal method.展开更多
--This paper presents a novel time delay estimation （TDE） method using the concept of entropy. The relative delay is estimated by minimizing the estimated joint entropy of multiple sensor output signals. When estima...--This paper presents a novel time delay estimation （TDE） method using the concept of entropy. The relative delay is estimated by minimizing the estimated joint entropy of multiple sensor output signals. When estimating the entropy, the information about the prior distribution of the source signal is not required. Instead, the Parzen window estimator is employed to estimate the density function of the source signal from multiple sensor output signals. Meanwhile, based on the Parzen window estimator, the Renyi＇s quadratic entropy （RQE） is incorporated to effectively and efficiently estimate the high-dimensional joint entropy of the multichannel outputs. Furthermore, a modified form of the joint entropy for embedding information about reverberation （multipath reflections） for speech signals is introduced to enhance the estimator＇s robustness against reverberation.展开更多
Neonicotinoids(NEOs),a large class of organic compounds,are a type of commonly used pesticide for crop protection.Their uptake and accumulation in plants are prerequisites for their intra-and intercellular move-ments,...Neonicotinoids(NEOs),a large class of organic compounds,are a type of commonly used pesticide for crop protection.Their uptake and accumulation in plants are prerequisites for their intra-and intercellular move-ments,transformation,and function.Understanding the molecular mechanisms that underpin NEO uptake by plants is crucial for effective application,which remains elusive.Here,we demonstrate that NEOs enter plant cells primarily through the transmembrane symplastic pathway and accumulate mainly in the cytosol.Two plasma membrane intrinsic proteins discovered in Brassica rapa,BraPIP1;1 and BraPIP2;1,were found to encode aquaporins(AQPs)that are highly permeable to NEOs in different plant species and facilitate NEO subcellular diffusion and accumulation.Their conserved transport function was further demonstrated in Xenopus laevis oocyte and yeast assays.BraPIP1;1 and BraPIP2;1 gene knockouts and interaction as-says suggested that their proteins can form functional heterotetramers.Assessment of the potential of mean force indicated a negative correlation between NEO uptake and the energy barrier of BraPIP1;1 chan-nels.This study shows that AQPs transport organic compounds with greater osmolarity than previously thought,providing new insight into the molecular mechanisms of organic compound uptake and facilitating innovations in systemic pesticides.展开更多
After nanocrystals synthesis,the purification process with anti-solvents is an essential step to get clean nanocrystals,which could get rid of the by-products of the synthesis.It is generally recognized that this proc...After nanocrystals synthesis,the purification process with anti-solvents is an essential step to get clean nanocrystals,which could get rid of the by-products of the synthesis.It is generally recognized that this process could bring a positive effect for the afterward optoelectronic applications.Unfortunately,we found that the optical properties and photostability of perovskite CsPbBr3 nanocrystals were unavoidably deteriorated after they were washed with anti-solvents,and this deterioration is strongly related to the decreasing of surface ligands density.Therefore,in this paper,we tried to purposely not wash the CsPbBr3 nanocrystals solution after adding didodecyl dimethylammonium bromide (DDAB),and found the existing of DDAB in solution could result in a dramatically enhanced photostability.Inspired by these results,we proposed a new strategy to stabilize perovskite nanocrystals from the view of packaging process:adding protective ligands into the perovskite nanocrystals resin directly,then encapsulating them on blue light-emitting diodes (LED) chips.Surprisingly,stable LED devices (20 mA,2.7V) were achieved by this way,which can keep 80% of the initial photoluminescence (PL) intensity for more than 50 h,while the devices with CsPbBr3 nanocrystals without adding protective ligands into resin dropped to 50% of their initial PL intensity within 6 h.This approach offers a new thought to stabilize perovskite nanocrystals as down-conversion phosphor in quantum dots liquid crystal display.展开更多
Distance effect has been regarded as the best established marker of basic numerical magnitude processes and is related to individual mathematical abilities. A larger behavioral distance effect is suggested to be conco...Distance effect has been regarded as the best established marker of basic numerical magnitude processes and is related to individual mathematical abilities. A larger behavioral distance effect is suggested to be concomitant with lower mathematical achievement in children. However, the relationship between distance effect and superior mathematical abilities is unclear. One could get superior mathematical abilities by acquiring the skill of abacus-based mental calculation （AMC）, which can be used to solve calculation problems with exceptional speed and high accuracy. In the current study, we explore the relationship between distance effect and superior mathematical abilities by examining whether and how the AMC training modifies numerical magnitude processing. Thus, mathematical competencies were tested in 18 abacus-trained children （who accepted the AMC training） and 18 non-trained children. Electroencephalography （EEG） waveforms were recorded when these children executed numerical comparison tasks in both Arabic digit and dot array forms. We found that： （a） the abacus-trained group had superior mathematical abilities than their peers; （b） distance effects were found both in behavioral results and on EEG wave- forms; （c） the distance effect size of the average amplitude on the late negative-going component was different between groups in the digit task, with a larger effect size for abacus-trained children; （d） both the behavioral and EEG distance effects were modulated by the notation. These results revealed that the neural substrates of magnitude processing were modified by AMC training, and suggested that the mechanism of the representation of numerical magnitude for children with superior mathematical abilities was different from their peers. In addition, the results provide evidence for a view of non-abstract numerical representation.展开更多
文摘Broadband wireless channels are often time dispersive and become strongly frequency selective in delay spread domain. Commonly, these channels are composed of a few dominant coefficients and a large part of coefficients are approximately zero or under noise floor. To exploit sparsity of multi-path channels (MPCs), there are various methods have been proposed. They are, namely, greedy algorithms, iterative algorithms, and convex program. The former two algorithms are easy to be implemented but not stable;on the other hand, the last method is stable but difficult to be implemented as practical channel estimation problems be-cause of computational complexity. In this paper, we introduce a novel channel estimation strategy using smooth L0 (SL0) algorithm which combines stable and low complexity. Computer simulations confirm the effectiveness of the introduced algorithm. We also give various simulations to verify the sensing training signal method.
基金supported by the National Natural Science Foundation of China under Grant No.61172140‘985’ Key Projects for Excellent Teaching Team Supporting (postgraduate) under Grant No.A1098522-02
文摘--This paper presents a novel time delay estimation （TDE） method using the concept of entropy. The relative delay is estimated by minimizing the estimated joint entropy of multiple sensor output signals. When estimating the entropy, the information about the prior distribution of the source signal is not required. Instead, the Parzen window estimator is employed to estimate the density function of the source signal from multiple sensor output signals. Meanwhile, based on the Parzen window estimator, the Renyi＇s quadratic entropy （RQE） is incorporated to effectively and efficiently estimate the high-dimensional joint entropy of the multichannel outputs. Furthermore, a modified form of the joint entropy for embedding information about reverberation （multipath reflections） for speech signals is introduced to enhance the estimator＇s robustness against reverberation.
基金supported in part by the National Natural Science Foundation of China (nos.32172448 and 3177219)the Jiangsu Agricultural Science and Technology Innovation Fund (CX (21)2002)the National Key Research and Development Program (2021YFD1700803),and the USDA (HAW05032R).
文摘Neonicotinoids(NEOs),a large class of organic compounds,are a type of commonly used pesticide for crop protection.Their uptake and accumulation in plants are prerequisites for their intra-and intercellular move-ments,transformation,and function.Understanding the molecular mechanisms that underpin NEO uptake by plants is crucial for effective application,which remains elusive.Here,we demonstrate that NEOs enter plant cells primarily through the transmembrane symplastic pathway and accumulate mainly in the cytosol.Two plasma membrane intrinsic proteins discovered in Brassica rapa,BraPIP1;1 and BraPIP2;1,were found to encode aquaporins(AQPs)that are highly permeable to NEOs in different plant species and facilitate NEO subcellular diffusion and accumulation.Their conserved transport function was further demonstrated in Xenopus laevis oocyte and yeast assays.BraPIP1;1 and BraPIP2;1 gene knockouts and interaction as-says suggested that their proteins can form functional heterotetramers.Assessment of the potential of mean force indicated a negative correlation between NEO uptake and the energy barrier of BraPIP1;1 chan-nels.This study shows that AQPs transport organic compounds with greater osmolarity than previously thought,providing new insight into the molecular mechanisms of organic compound uptake and facilitating innovations in systemic pesticides.
基金the Major National Science and Technology Special Project of Water Pollution Control and Remediation (No.2017ZX07202)the National Natural Science Foundation of China (No.21773155)Shanghai Sailing Program (No.19YF1422200).
文摘After nanocrystals synthesis,the purification process with anti-solvents is an essential step to get clean nanocrystals,which could get rid of the by-products of the synthesis.It is generally recognized that this process could bring a positive effect for the afterward optoelectronic applications.Unfortunately,we found that the optical properties and photostability of perovskite CsPbBr3 nanocrystals were unavoidably deteriorated after they were washed with anti-solvents,and this deterioration is strongly related to the decreasing of surface ligands density.Therefore,in this paper,we tried to purposely not wash the CsPbBr3 nanocrystals solution after adding didodecyl dimethylammonium bromide (DDAB),and found the existing of DDAB in solution could result in a dramatically enhanced photostability.Inspired by these results,we proposed a new strategy to stabilize perovskite nanocrystals from the view of packaging process:adding protective ligands into the perovskite nanocrystals resin directly,then encapsulating them on blue light-emitting diodes (LED) chips.Surprisingly,stable LED devices (20 mA,2.7V) were achieved by this way,which can keep 80% of the initial photoluminescence (PL) intensity for more than 50 h,while the devices with CsPbBr3 nanocrystals without adding protective ligands into resin dropped to 50% of their initial PL intensity within 6 h.This approach offers a new thought to stabilize perovskite nanocrystals as down-conversion phosphor in quantum dots liquid crystal display.
基金supported by the National High-Tech R&D Program(863)of China(Nos.2012AA011603 and 2012AA011602)the National Natural Science Foundation of China(Nos.30900389 and 31270026)
文摘Distance effect has been regarded as the best established marker of basic numerical magnitude processes and is related to individual mathematical abilities. A larger behavioral distance effect is suggested to be concomitant with lower mathematical achievement in children. However, the relationship between distance effect and superior mathematical abilities is unclear. One could get superior mathematical abilities by acquiring the skill of abacus-based mental calculation （AMC）, which can be used to solve calculation problems with exceptional speed and high accuracy. In the current study, we explore the relationship between distance effect and superior mathematical abilities by examining whether and how the AMC training modifies numerical magnitude processing. Thus, mathematical competencies were tested in 18 abacus-trained children （who accepted the AMC training） and 18 non-trained children. Electroencephalography （EEG） waveforms were recorded when these children executed numerical comparison tasks in both Arabic digit and dot array forms. We found that： （a） the abacus-trained group had superior mathematical abilities than their peers; （b） distance effects were found both in behavioral results and on EEG wave- forms; （c） the distance effect size of the average amplitude on the late negative-going component was different between groups in the digit task, with a larger effect size for abacus-trained children; （d） both the behavioral and EEG distance effects were modulated by the notation. These results revealed that the neural substrates of magnitude processing were modified by AMC training, and suggested that the mechanism of the representation of numerical magnitude for children with superior mathematical abilities was different from their peers. In addition, the results provide evidence for a view of non-abstract numerical representation.
