This review begins with a brief commentary on the diversity of placentation mechanisms, and then goes on to examine the extensive alterations which occur in the plasma membrane of uterine epithelial cells during early...This review begins with a brief commentary on the diversity of placentation mechanisms, and then goes on to examine the extensive alterations which occur in the plasma membrane of uterine epithelial cells during early pregnancy across species. Ultrastructural, biochemical and more general morphological data reveal that strikingly common phenomena occur in this plasma membrane during early pregnancy despite the diversity of placental types-from epitheliochorial to hemochorial, which ultimately form in different species. To encapsulate the concept that common morphological and molecular alterations occur across species, that they are found basolaterally as well as apically, and that moreover they are an ongoing process during much of early pregnancy, not just an event at the time attachment, the term 'plasma membrane transformation' is suggested which also emphasises that alterations in this plasma membrane during early pregnancy are key to uterine receptivity.展开更多
In this paper, a new signal separation method mainly for AM-FM components blended in noises is revisited based on the new derived time-varying bandpass filter (TVBF), which can separate the AM-FM components whose freq...In this paper, a new signal separation method mainly for AM-FM components blended in noises is revisited based on the new derived time-varying bandpass filter (TVBF), which can separate the AM-FM components whose frequencies have overlapped regions in Fourier transform domain and even have crossed points in time-frequency distribution (TFD) so that the proposed TVBF seems like a “soft-cutter” that cuts the frequency domain to snaky slices with rational physical sense. First, the Hilbert transform based decomposition is analyzed for the analysis of nonstationary signals. Based on the above analysis, a hypothesis under a certain condition that AM-FM components can be separated successfully based on Hilbert transform and the assisted signal is developed, which is supported by representative experiments and theoretical performance analyses on a error bound that is shown to be proportional to the product of frequency width and noise variance. The assisted signals are derived from the refined time-frequency distributions via image fusion and least squares optimization. Experiments on man-made and real-life data verify the efficiency of the proposed method and demonstrate the advantages over the other main methods.展开更多
In this paper, the following important problem is answered: Under what condition can the Hilbert transform be put in the simple form. Then, using the Hilbert technique, it is demonstrated that, with some relative weak...In this paper, the following important problem is answered: Under what condition can the Hilbert transform be put in the simple form. Then, using the Hilbert technique, it is demonstrated that, with some relative weak restrictions, the particle motion at the sea surface and energy transmission may be obtained from a wave record. The analysis show that for the two-dimensional and narrow-band mo- tion (or a physical phenomena, such as capillary waves breaking, which satisfy the narrow-band approx- imation) the local kinetic energy fluctuates in time as the envelope equared multiplied by a constant factor and can be obtained directly from a wave record. It is pointed that the local fluctuatiom of the potential energy as well as the local fluctuations of the total energy can be separated into a slowly varying part and a more rapid oscillating Part. Both Parts can be evaluated by meaas of the Hilbert transform. Finally, a physical interpretation of the envelope of the two-dimensional capillary waves as well as the method for wave group analysis is presented.展开更多
Aluminum-lithium(Al-Li)alloy is one of the most promising lightweight structural materials in the aeronautic and aerospace industries.The key to achieving their excellent mechanical properties lies in tailoring T1 str...Aluminum-lithium(Al-Li)alloy is one of the most promising lightweight structural materials in the aeronautic and aerospace industries.The key to achieving their excellent mechanical properties lies in tailoring T1 strengthening precipitates;however,the nucleation of such nanoparticles remains unknown.Combining atomic resolution HAADF-STEM with first-principles calculations based on the density functional theory(DFT),here,we report a counterintuitive nucleation mechanism of the T1 that evolves from an Eshelby inclusion with unstable stacking faults.This precursor is accelerated by Ag-Mg clusters to reduce the barrier,forming the structural framework.In addition,these Ag-Mg clusters trap the free Cu and Li to prepare the chemical compositions for T1.Our findings provide a new perspective on the phase transformations of complex precipitates through solute clusters in terms of geometric structure and chemical bonding functions.展开更多
The United Nations’2030 Agenda for Sustainable Development sets seventeen Sustainable Development Goals(SDGs)to be achieved by 2030.Earth observation are needed that can support the development and validation of tran...The United Nations’2030 Agenda for Sustainable Development sets seventeen Sustainable Development Goals(SDGs)to be achieved by 2030.Earth observation are needed that can support the development and validation of transformation policies to make progress towards the SDGs.A participatory and inclusive goal-based approach(GBA)is introduced that links societal goals,targets and indicators to Essential Transformation Variables(ETVs)of the human and non-human environment.The GBA is complementary to the widely used expertbased approach.The GBA is applied to the SDGs at the goal,target and indicator levels.The high-level conceptual model used for the SDGs is humanity embedded in the Earth’s life-support system(ELSS).At the goal level,very few of the SDGs are directly focusing on the ELSS and its physiology.Most of the SDG Targets focus on transformations in society and the built environment.Having targets that explicitly focus on the physiology of the ELSS would be important for sustainability.Most of the current indicator measure the built environment and the embedded social fabric.Sustainable development requires a functioning ELSS,and to ensure this,complementary indicators that bring environmental aspects to the monitoring of SDG targets are needed.展开更多
The phase stability of the Laves phase Cr2Nb in a two-phase Cr-Cr2Nb alloy produced by arc-melting was investigated using X-ray diffraction, transmission electron microscopy and selected area electron diffraction. The...The phase stability of the Laves phase Cr2Nb in a two-phase Cr-Cr2Nb alloy produced by arc-melting was investigated using X-ray diffraction, transmission electron microscopy and selected area electron diffraction. The experimental results indicated that the as-cast ingot was consisted of C15-Cr2Nb and Cr phases; the intermediate C36 and high-temperature C14 modifications of Cr2Nb, reported in literatures, were not detected in this study. These results, combined with a detailed analysis of the actual solidification conditions, revealed that the C14-Cr2Nb was a metastable rather than a stable high-temperature modification. Moreover, a kind of extremely fine lamellar structure was found to be randomly distributed in the eutectic cells, which may be formed by decomposition of the supersaturated C15-Cr2Nb via a discontinuous precipitation reaction.展开更多
The importance of basic hypergeometric series has been widely recognized. For non specialists, it is necessary to have a quick introduction to this classical but flourishing subject. An effort along this direction wil...The importance of basic hypergeometric series has been widely recognized. For non specialists, it is necessary to have a quick introduction to this classical but flourishing subject. An effort along this direction will be made in the present article.展开更多
WITH the increase of heating temperature, phase of pyrophyllite will undergo a series of transformations. Former scholars have done some work in this respect; the temperature spans,however, were normally not more than...WITH the increase of heating temperature, phase of pyrophyllite will undergo a series of transformations. Former scholars have done some work in this respect; the temperature spans,however, were normally not more than 1150℃ and no relatively comprehensive results have been reported. Thus, the features of the phases from indoor temperature to melting point (1710℃±) for pyrophyllite and the entire evolutionary process of the phases are uncertain.展开更多
In shallow water, during the wave propagation the nonlinear and wave breaking effect must be taken into account. In this peper a simplified hybrid method was proposed, in which a combined frequency and time domain ana...In shallow water, during the wave propagation the nonlinear and wave breaking effect must be taken into account. In this peper a simplified hybrid method was proposed, in which a combined frequency and time domain analysis was used. By using authors' method, the process are quite simple and easy to run on a PC computer, but the nonlinear and wave bleaking effect was still been considered. The computed data coincide authors' test results quite well.展开更多
文摘This review begins with a brief commentary on the diversity of placentation mechanisms, and then goes on to examine the extensive alterations which occur in the plasma membrane of uterine epithelial cells during early pregnancy across species. Ultrastructural, biochemical and more general morphological data reveal that strikingly common phenomena occur in this plasma membrane during early pregnancy despite the diversity of placental types-from epitheliochorial to hemochorial, which ultimately form in different species. To encapsulate the concept that common morphological and molecular alterations occur across species, that they are found basolaterally as well as apically, and that moreover they are an ongoing process during much of early pregnancy, not just an event at the time attachment, the term 'plasma membrane transformation' is suggested which also emphasises that alterations in this plasma membrane during early pregnancy are key to uterine receptivity.
文摘In this paper, a new signal separation method mainly for AM-FM components blended in noises is revisited based on the new derived time-varying bandpass filter (TVBF), which can separate the AM-FM components whose frequencies have overlapped regions in Fourier transform domain and even have crossed points in time-frequency distribution (TFD) so that the proposed TVBF seems like a “soft-cutter” that cuts the frequency domain to snaky slices with rational physical sense. First, the Hilbert transform based decomposition is analyzed for the analysis of nonstationary signals. Based on the above analysis, a hypothesis under a certain condition that AM-FM components can be separated successfully based on Hilbert transform and the assisted signal is developed, which is supported by representative experiments and theoretical performance analyses on a error bound that is shown to be proportional to the product of frequency width and noise variance. The assisted signals are derived from the refined time-frequency distributions via image fusion and least squares optimization. Experiments on man-made and real-life data verify the efficiency of the proposed method and demonstrate the advantages over the other main methods.
文摘In this paper, the following important problem is answered: Under what condition can the Hilbert transform be put in the simple form. Then, using the Hilbert technique, it is demonstrated that, with some relative weak restrictions, the particle motion at the sea surface and energy transmission may be obtained from a wave record. The analysis show that for the two-dimensional and narrow-band mo- tion (or a physical phenomena, such as capillary waves breaking, which satisfy the narrow-band approx- imation) the local kinetic energy fluctuates in time as the envelope equared multiplied by a constant factor and can be obtained directly from a wave record. It is pointed that the local fluctuatiom of the potential energy as well as the local fluctuations of the total energy can be separated into a slowly varying part and a more rapid oscillating Part. Both Parts can be evaluated by meaas of the Hilbert transform. Finally, a physical interpretation of the envelope of the two-dimensional capillary waves as well as the method for wave group analysis is presented.
基金supported by the National Natural Science Foundation of China(grant number 52073030)National Natural Science Foundation of China-Guangxi Joint Fund(U20A20276).
文摘Aluminum-lithium(Al-Li)alloy is one of the most promising lightweight structural materials in the aeronautic and aerospace industries.The key to achieving their excellent mechanical properties lies in tailoring T1 strengthening precipitates;however,the nucleation of such nanoparticles remains unknown.Combining atomic resolution HAADF-STEM with first-principles calculations based on the density functional theory(DFT),here,we report a counterintuitive nucleation mechanism of the T1 that evolves from an Eshelby inclusion with unstable stacking faults.This precursor is accelerated by Ag-Mg clusters to reduce the barrier,forming the structural framework.In addition,these Ag-Mg clusters trap the free Cu and Li to prepare the chemical compositions for T1.Our findings provide a new perspective on the phase transformations of complex precipitates through solute clusters in terms of geometric structure and chemical bonding functions.
基金This work was supported by Horizon 2020 Framework Programme[641538]National Aeronautics and Space Administration[80NSSC17K0241].
文摘The United Nations’2030 Agenda for Sustainable Development sets seventeen Sustainable Development Goals(SDGs)to be achieved by 2030.Earth observation are needed that can support the development and validation of transformation policies to make progress towards the SDGs.A participatory and inclusive goal-based approach(GBA)is introduced that links societal goals,targets and indicators to Essential Transformation Variables(ETVs)of the human and non-human environment.The GBA is complementary to the widely used expertbased approach.The GBA is applied to the SDGs at the goal,target and indicator levels.The high-level conceptual model used for the SDGs is humanity embedded in the Earth’s life-support system(ELSS).At the goal level,very few of the SDGs are directly focusing on the ELSS and its physiology.Most of the SDG Targets focus on transformations in society and the built environment.Having targets that explicitly focus on the physiology of the ELSS would be important for sustainability.Most of the current indicator measure the built environment and the embedded social fabric.Sustainable development requires a functioning ELSS,and to ensure this,complementary indicators that bring environmental aspects to the monitoring of SDG targets are needed.
基金financially supported by the National Natural Science Foundation of China(Nos.50971101,51074127 and 51104120)
文摘The phase stability of the Laves phase Cr2Nb in a two-phase Cr-Cr2Nb alloy produced by arc-melting was investigated using X-ray diffraction, transmission electron microscopy and selected area electron diffraction. The experimental results indicated that the as-cast ingot was consisted of C15-Cr2Nb and Cr phases; the intermediate C36 and high-temperature C14 modifications of Cr2Nb, reported in literatures, were not detected in this study. These results, combined with a detailed analysis of the actual solidification conditions, revealed that the C14-Cr2Nb was a metastable rather than a stable high-temperature modification. Moreover, a kind of extremely fine lamellar structure was found to be randomly distributed in the eutectic cells, which may be formed by decomposition of the supersaturated C15-Cr2Nb via a discontinuous precipitation reaction.
文摘The importance of basic hypergeometric series has been widely recognized. For non specialists, it is necessary to have a quick introduction to this classical but flourishing subject. An effort along this direction will be made in the present article.
文摘WITH the increase of heating temperature, phase of pyrophyllite will undergo a series of transformations. Former scholars have done some work in this respect; the temperature spans,however, were normally not more than 1150℃ and no relatively comprehensive results have been reported. Thus, the features of the phases from indoor temperature to melting point (1710℃±) for pyrophyllite and the entire evolutionary process of the phases are uncertain.
文摘In shallow water, during the wave propagation the nonlinear and wave breaking effect must be taken into account. In this peper a simplified hybrid method was proposed, in which a combined frequency and time domain analysis was used. By using authors' method, the process are quite simple and easy to run on a PC computer, but the nonlinear and wave bleaking effect was still been considered. The computed data coincide authors' test results quite well.