In this paper the authors generalize the classic random bipartite graph model, and define a model of the random bipartite multigraphs as follows：let m = m（n） be a positive integer-valued function on n and ζ（n,m;{...In this paper the authors generalize the classic random bipartite graph model, and define a model of the random bipartite multigraphs as follows：let m = m（n） be a positive integer-valued function on n and ζ（n,m;{pk}） the probability space consisting of all the labeled bipartite multigraphs with two vertex sets A ={a_1,a_2,...,a_n} and B = {b_1,b_2,...,b_m}, in which the numbers t_（ai）,b_j of the edges between any two vertices a_i∈A and b_j∈ B are identically distributed independent random variables with distribution P{t_（ai）,b_j=k}=pk,k=0,1,2,...,where pk ≥0 and ∞Σk=0 pk=1. They obtain that X_（c,d,A）, the number of vertices in A with degree between c and d of G_（n,m）∈ζ（n, m;{pk}） has asymptotically Poisson distribution, and answer the following two questions about the space ζ（n,m;{pk}） with {pk} having geometric distribution, binomial distribution and Poisson distribution, respectively. Under which condition for {pk} can there be a function D（n） such that almost every random multigraph G_（n,m）∈ζ（n,m;{pk}） has maximum degree D（n）in A？ under which condition for {pk} has almost every multigraph G（n,m）∈ζ（n,m;{pk}） a unique vertex of maximum degree in A？展开更多
Recent progress in technology has allowed an extraordinary refinement of our knowledge of transcriptomes, revealing their unexpected complexity. In addition to the large number of siRNAs and miRNAs, many noncoding RNA...Recent progress in technology has allowed an extraordinary refinement of our knowledge of transcriptomes, revealing their unexpected complexity. In addition to the large number of siRNAs and miRNAs, many noncoding RNA species are now known to be transcribed by RNA polymerase II （RNAPII）, in proximity or overlapping to known transcription units in both sense and antisense orientations, as well as from DNA regions previously thought to be transcriptionally inert or silent.展开更多
Amorphous Si_(1-x)Sn_x alloys have been prepared by co-evaporation onto substrates maintained at liquid nitrogen temperature. Their atomic structure is investigated using density measurements, scanning high-energy ele...Amorphous Si_(1-x)Sn_x alloys have been prepared by co-evaporation onto substrates maintained at liquid nitrogen temperature. Their atomic structure is investigated using density measurements, scanning high-energy electron diffraction and Mossbauer spectroscopy. The optical and electrical properties are reported. Then, a method to hydrogenate the films during the evaporation process is described and applied to the preparation of amorphous semiconductors from pure silicon to pure tin. Finally, multilayers of type Si / Si:H / ... or Si:H / Si:D / ... are studied. The modulation of hydrogen is shown by low-angle neutron scattering and measurements of hydrogen diffusivity are presented.展开更多
Electronic and magnetic structures of zinc blende ZnO doped with V impurities are studied by first-principles calculations based on the Korringa-Kohn-Rostoker （KKR） method combined with the coherent potential approx...Electronic and magnetic structures of zinc blende ZnO doped with V impurities are studied by first-principles calculations based on the Korringa-Kohn-Rostoker （KKR） method combined with the coherent potential approximation （CPA）. Calculations for the substitution of O by N or P are performed and the magnetic moment is found to be sensitive to the N or P content. Furthermore, the system exhibits a half-metallic band structure accompanied by the broadening of vanadium bands. The mechanism responsible for ferromagnetism is also discussed and the stability of the ferromagnetic state compared with that of the paramagnetic state is systematically investigated by calculating the total energy difference between them by using supercell method.展开更多
Some peaks have been observed in plot of conductivity versus temperature for amorphous ionic conductor in Li_(2)O-SiO_(2)-V_(2)O_(5) system.It has been shown from X-ray and DTA data that the amorphous ionic conductors...Some peaks have been observed in plot of conductivity versus temperature for amorphous ionic conductor in Li_(2)O-SiO_(2)-V_(2)O_(5) system.It has been shown from X-ray and DTA data that the amorphous ionic conductors crystallize in steps.Every conductivity peak or conductivity enhancement was caused by a crystallization step.展开更多
This note is a research announcement on[18]for the deformation limit of Moishezon manifolds and most all of the further details can be found there.1 Main Results The deformation limit problem is central in deformation...This note is a research announcement on[18]for the deformation limit of Moishezon manifolds and most all of the further details can be found there.1 Main Results The deformation limit problem is central in deformation theory,with which the following longstanding conjecture is concerned.展开更多
The objective of this work is to verify the validity of the Spink's model at the lower shelf of the transition curve CVN-T.Knowing that in this field of temperatures,previous results have shown that CVN is sensiti...The objective of this work is to verify the validity of the Spink's model at the lower shelf of the transition curve CVN-T.Knowing that in this field of temperatures,previous results have shown that CVN is sensitive to the steel micro-structure of the steel,heat treatments and the existence of defects such as those caused by internal hydrogen.Mild steel,with and without internal hydrogen and a metastable austenitic 2404 alloyed steel transformed at-196℃to about 90%martensite are studied.Standard charpy specimens with different notch root radii varying from 0 to 1 mm are used to measure fracture toughness by applying j-integral and also to measure the impact energy CVN.For all,bending tests were performed and the tests temperature was-196℃.For mild steel without internal hydrogen,the changes in both fracture toughness and impact toughness as a function of notch acuity coincide perfectly and are,also,in good agreement with those obtained at the upper shelf by Ritchie et al in AISI 4340 steel in two different heat treatments.However;in the case of mild steel severely charged with internal hydrogen and containing more than 10 ppm H2,which promotes high density of defects in the grain boundaries,the two linear relations are not similar but for the two cases of zero notch radii are the same and equal to 0 mm.The bi-phases 2404 alloyed steel shows that the slopes and the critical notch root radii of the linear relations are also different.The strain induced martensite from the residual austenite,/during the fracture toughness measurements at-196℃,with low strain rate is assumed to be inhibited.Only the strain rate sensitivity is responsible for this difference.However;for all three cases studied at-196℃and for the results obtained at the upper shelf by Rithie et al,the effective notch root radii whether measured by fracture toughness or by impact energy tests are the same.The fracture type in mild steel free from internal hydrogen is by macro-cleavage,while in the presence of internal hydrogen,macro-cleavage and inter-granular feature,with large cracks are observed.After fracture toughness tests,the fracture surface of the aged martensite 2404 alloyed steel is by fine dimples"ductile-fragile"feature.The main conclusion is that by applying the Spink's model described above,large dimension specimens satisfying the standard LFEM criterion(AS TM E23-01,2001)are not necessary.展开更多
Intracontinental deformation is one of the most interesting problems in tectonics. But so far little attention has been paid to rock deformation, metamorphism and magmatism related with large-scale displacement and ro...Intracontinental deformation is one of the most interesting problems in tectonics. But so far little attention has been paid to rock deformation, metamorphism and magmatism related with large-scale displacement and rotation of these blocks. In this note, we take the Ailaoshan-Red River fault (ARF)zone in western Yunnan as an example and discuss the kinematics and dynamics of the fault With its neighbouring blocks in the Tertiary.展开更多
Exploring and interpreting the mode of cognition and behavioral patterns of prehistoric hunter-gatherers is always one of the main goals of current Paleolithic research. In the 1940s, French prehistorians proposed the...Exploring and interpreting the mode of cognition and behavioral patterns of prehistoric hunter-gatherers is always one of the main goals of current Paleolithic research. In the 1940s, French prehistorians proposed the technological method for studying lithic assemblages which opened a brand-new perspective on the prehistoric domain. In the 1960s, French ethnographer and anthropologist André Leroi-Gourhan proposed the concept "chane opératoire" and established the theory of lithic technological study. After the 1980s, the concept "chane opératoire" was substituted for two different but complementary concepts: techno-cognition and techno-economy, which contributed not only to revealing the technical knowledge and know-how applied during lithic production but also to interpreting the technical behavior of prehistoric hunter-gatherers from social and economic viewpoints. The lithic technological study of the Guanyindong site, presented in this paper, was carried out for the first time by applying lithic technological method developed by French prehistorians to the Chinese materials. Our analytical results demonstrated that the débitage system of Guanyindong is quite distinct from the concept Levallois largely used in Europe, Near-East and Africa. The differentiation between these two débitage modes may contribute to exploring and interpreting the relationship in Middle Paleolithic between China and Europe, Near-East and Africa.展开更多
Redonda is a small volcanic Caribbean island that is home to at least 4 endemic lizard species,including the Critically Endangered ground lizard(Pholidoscelis atratus).Black rats(Rattus rattus)and domestic goats(Capra...Redonda is a small volcanic Caribbean island that is home to at least 4 endemic lizard species,including the Critically Endangered ground lizard(Pholidoscelis atratus).Black rats(Rattus rattus)and domestic goats(Capra hircus)were introduced to the island at some time after its discovery by Europeans in the late 1500s.They had a devastating effect on the island,resulting in the loss of nearly all trees and most of the ground vegetation.Point count surveys of P.atratus in 2012 indicated low densities,and the invasive rats were observed hunting and preying on the lizards.Both populations of rats and goats were successfully removed in 2017 as part of an ecological restoration program,and native vegetation and invertebrate populations have increased rapidly since.Population surveys in 2017,2018,and 2019 show the lizard population has increased by more than sixfold.In 2017,as rats and goats were being removed,we evaluated the morphology and escape behavior of this species and repeated these measurements 1 year later.We observed that P.atratus had become bolder,with a reduced flight distance.We also detected changes in limb morphology related to locomotion and suggest possible explanations that will need to be further investigated in the future.These results show how the removal of invasive species can rapidly affect lizard population recovery and behavior,potentially restoring island ecosystems to their pre-human interference dynamics.展开更多
We report a non-destructive characterization of planar two-dimensional （2D） photonic crystals （PhCs） made in silicon on insulator （SOI） wafers using ellipsometric or Fourier transformed infrared （FTIR） spectro...We report a non-destructive characterization of planar two-dimensional （2D） photonic crystals （PhCs） made in silicon on insulator （SOI） wafers using ellipsometric or Fourier transformed infrared （FTIR） spectroscope. At large wavelengths, devices behave as homogeneous isotropic materials defined by an effective filling factor. The experimental results related to the PhC limited dimensions confirm this characterization.展开更多
This paper presents a statement of the works performed in L.E.M.T.A by the members of the thermal and mechanical heterogeneous media research group during the last six years concerning the solving of coupled conductiv...This paper presents a statement of the works performed in L.E.M.T.A by the members of the thermal and mechanical heterogeneous media research group during the last six years concerning the solving of coupled conductive and radiative heat transfers within a multilayer and semi-transparent“wall”.Out of the authors,this paper allows to take inspiration from the works of D.Maillet,M.Lazard and V.Manias[19,20,21].The aim of these works is to represent in a macroscopic way,with the minimum number of thermophysical parameters,the heat transfers in a plane system composed of semi-transparent media.The approach we propose is semi-analytic(Kernel substitution technique,Laplace transformation)and allow to obtain in the Laplace domain an analytical solution that can be easily used.This method can be applied in two main scopes of applications:the estimation of thermophysical properties(phononic conductivity,optical thickness,Planck number for instance)of semi-transparent materials(glasses,crystals,glass wool,semi-conductors,synthetic diamonds,vitroceramics and so on)and the modelling of processes with semitransparent walls(for instance bottles forming,flat glass production,drying of paper).The method will be first presented and validated and two examples of applications will be then given.This method can be applied to semitransparent walls that emit,absorb and scatter the radiant energy(participating medium).It appears from the principle of a Kernel substitution technique applied to the radiative flux expression and initially introduced by Lick[1]that allows to change the character of the governing heat equation from the integro-differential form to a purely differential one.In the case of limiting cases of purely scattering and purely absorbing media,the solution of the radiative transfer equation is exact.In the general case,we make a two-flux approximation.In all cases,we assume a linear transfer and use the Laplace transform.The method can be applied to grey or grey by bands media,with isotropic or anisotropic scattering.The advantage of the method is fast computational times for good precision.展开更多
文摘In this paper the authors generalize the classic random bipartite graph model, and define a model of the random bipartite multigraphs as follows：let m = m（n） be a positive integer-valued function on n and ζ（n,m;{pk}） the probability space consisting of all the labeled bipartite multigraphs with two vertex sets A ={a_1,a_2,...,a_n} and B = {b_1,b_2,...,b_m}, in which the numbers t_（ai）,b_j of the edges between any two vertices a_i∈A and b_j∈ B are identically distributed independent random variables with distribution P{t_（ai）,b_j=k}=pk,k=0,1,2,...,where pk ≥0 and ∞Σk=0 pk=1. They obtain that X_（c,d,A）, the number of vertices in A with degree between c and d of G_（n,m）∈ζ（n, m;{pk}） has asymptotically Poisson distribution, and answer the following two questions about the space ζ（n,m;{pk}） with {pk} having geometric distribution, binomial distribution and Poisson distribution, respectively. Under which condition for {pk} can there be a function D（n） such that almost every random multigraph G_（n,m）∈ζ（n,m;{pk}） has maximum degree D（n）in A？ under which condition for {pk} has almost every multigraph G（n,m）∈ζ（n,m;{pk}） a unique vertex of maximum degree in A？
文摘Recent progress in technology has allowed an extraordinary refinement of our knowledge of transcriptomes, revealing their unexpected complexity. In addition to the large number of siRNAs and miRNAs, many noncoding RNA species are now known to be transcribed by RNA polymerase II （RNAPII）, in proximity or overlapping to known transcription units in both sense and antisense orientations, as well as from DNA regions previously thought to be transcriptionally inert or silent.
文摘Amorphous Si_(1-x)Sn_x alloys have been prepared by co-evaporation onto substrates maintained at liquid nitrogen temperature. Their atomic structure is investigated using density measurements, scanning high-energy electron diffraction and Mossbauer spectroscopy. The optical and electrical properties are reported. Then, a method to hydrogenate the films during the evaporation process is described and applied to the preparation of amorphous semiconductors from pure silicon to pure tin. Finally, multilayers of type Si / Si:H / ... or Si:H / Si:D / ... are studied. The modulation of hydrogen is shown by low-angle neutron scattering and measurements of hydrogen diffusivity are presented.
文摘Electronic and magnetic structures of zinc blende ZnO doped with V impurities are studied by first-principles calculations based on the Korringa-Kohn-Rostoker （KKR） method combined with the coherent potential approximation （CPA）. Calculations for the substitution of O by N or P are performed and the magnetic moment is found to be sensitive to the N or P content. Furthermore, the system exhibits a half-metallic band structure accompanied by the broadening of vanadium bands. The mechanism responsible for ferromagnetism is also discussed and the stability of the ferromagnetic state compared with that of the paramagnetic state is systematically investigated by calculating the total energy difference between them by using supercell method.
基金This work is supported by Natural Science Foundation of China.
文摘Some peaks have been observed in plot of conductivity versus temperature for amorphous ionic conductor in Li_(2)O-SiO_(2)-V_(2)O_(5) system.It has been shown from X-ray and DTA data that the amorphous ionic conductors crystallize in steps.Every conductivity peak or conductivity enhancement was caused by a crystallization step.
基金partially supported by National Natural Science Foundation of China(11671305,11771339,11922115)。
文摘This note is a research announcement on[18]for the deformation limit of Moishezon manifolds and most all of the further details can be found there.1 Main Results The deformation limit problem is central in deformation theory,with which the following longstanding conjecture is concerned.
文摘The objective of this work is to verify the validity of the Spink's model at the lower shelf of the transition curve CVN-T.Knowing that in this field of temperatures,previous results have shown that CVN is sensitive to the steel micro-structure of the steel,heat treatments and the existence of defects such as those caused by internal hydrogen.Mild steel,with and without internal hydrogen and a metastable austenitic 2404 alloyed steel transformed at-196℃to about 90%martensite are studied.Standard charpy specimens with different notch root radii varying from 0 to 1 mm are used to measure fracture toughness by applying j-integral and also to measure the impact energy CVN.For all,bending tests were performed and the tests temperature was-196℃.For mild steel without internal hydrogen,the changes in both fracture toughness and impact toughness as a function of notch acuity coincide perfectly and are,also,in good agreement with those obtained at the upper shelf by Ritchie et al in AISI 4340 steel in two different heat treatments.However;in the case of mild steel severely charged with internal hydrogen and containing more than 10 ppm H2,which promotes high density of defects in the grain boundaries,the two linear relations are not similar but for the two cases of zero notch radii are the same and equal to 0 mm.The bi-phases 2404 alloyed steel shows that the slopes and the critical notch root radii of the linear relations are also different.The strain induced martensite from the residual austenite,/during the fracture toughness measurements at-196℃,with low strain rate is assumed to be inhibited.Only the strain rate sensitivity is responsible for this difference.However;for all three cases studied at-196℃and for the results obtained at the upper shelf by Rithie et al,the effective notch root radii whether measured by fracture toughness or by impact energy tests are the same.The fracture type in mild steel free from internal hydrogen is by macro-cleavage,while in the presence of internal hydrogen,macro-cleavage and inter-granular feature,with large cracks are observed.After fracture toughness tests,the fracture surface of the aged martensite 2404 alloyed steel is by fine dimples"ductile-fragile"feature.The main conclusion is that by applying the Spink's model described above,large dimension specimens satisfying the standard LFEM criterion(AS TM E23-01,2001)are not necessary.
基金Project supported by the National Natural Science Foundation of China and C. N. R. S., France.
文摘Intracontinental deformation is one of the most interesting problems in tectonics. But so far little attention has been paid to rock deformation, metamorphism and magmatism related with large-scale displacement and rotation of these blocks. In this note, we take the Ailaoshan-Red River fault (ARF)zone in western Yunnan as an example and discuss the kinematics and dynamics of the fault With its neighbouring blocks in the Tertiary.
基金Supported by the National Basic Research Program of China (Grant No. 2006 CB806400)National Natural Science Foundation of China (Grant Nos. 40872023 and J0630965)Knowledge Innovation Program of the Chinese Academy of Sciences
文摘Exploring and interpreting the mode of cognition and behavioral patterns of prehistoric hunter-gatherers is always one of the main goals of current Paleolithic research. In the 1940s, French prehistorians proposed the technological method for studying lithic assemblages which opened a brand-new perspective on the prehistoric domain. In the 1960s, French ethnographer and anthropologist André Leroi-Gourhan proposed the concept "chane opératoire" and established the theory of lithic technological study. After the 1980s, the concept "chane opératoire" was substituted for two different but complementary concepts: techno-cognition and techno-economy, which contributed not only to revealing the technical knowledge and know-how applied during lithic production but also to interpreting the technical behavior of prehistoric hunter-gatherers from social and economic viewpoints. The lithic technological study of the Guanyindong site, presented in this paper, was carried out for the first time by applying lithic technological method developed by French prehistorians to the Chinese materials. Our analytical results demonstrated that the débitage system of Guanyindong is quite distinct from the concept Levallois largely used in Europe, Near-East and Africa. The differentiation between these two débitage modes may contribute to exploring and interpreting the relationship in Middle Paleolithic between China and Europe, Near-East and Africa.
基金This research was carried out under the auspices of the Redonda Restoration Programme,a collaborative program of the Government of Antigua and Barbuda,Environmental Awareness Group,British Mountaineering Council,Fauna&Flora International,Island Conservation and Wildlife Management International Ltd.Fieldwork between 2012 and 2019 was funded by grants from Darwin Initiative through UK Government funding(grant#23-003)Betty Liebert Trust,Disney Conservation Fund,Global Wildlife Conservation,National Fish&Wildlife Foundation(#51228)+2 种基金Taurus Foundation,and U.S.Fish andWildlife Service’s Neotropical Migratory Birds Conservation Act(grants#F10AP00785 and F17AP00667)with additional technical and material support from Caribbean Helicopters Ltd.and Syngenta Crop Protection AGSupport for field work for A.H.and C.M.D.was provided through the U.S.N.S.F.IOS-1354620 to J.LososA.H.A.H.and C.M.D.thank Ms.Nneka Nicholas(Department of Environment)for her assistance in procuring permits to conduct fieldwork.
文摘Redonda is a small volcanic Caribbean island that is home to at least 4 endemic lizard species,including the Critically Endangered ground lizard(Pholidoscelis atratus).Black rats(Rattus rattus)and domestic goats(Capra hircus)were introduced to the island at some time after its discovery by Europeans in the late 1500s.They had a devastating effect on the island,resulting in the loss of nearly all trees and most of the ground vegetation.Point count surveys of P.atratus in 2012 indicated low densities,and the invasive rats were observed hunting and preying on the lizards.Both populations of rats and goats were successfully removed in 2017 as part of an ecological restoration program,and native vegetation and invertebrate populations have increased rapidly since.Population surveys in 2017,2018,and 2019 show the lizard population has increased by more than sixfold.In 2017,as rats and goats were being removed,we evaluated the morphology and escape behavior of this species and repeated these measurements 1 year later.We observed that P.atratus had become bolder,with a reduced flight distance.We also detected changes in limb morphology related to locomotion and suggest possible explanations that will need to be further investigated in the future.These results show how the removal of invasive species can rapidly affect lizard population recovery and behavior,potentially restoring island ecosystems to their pre-human interference dynamics.
文摘We report a non-destructive characterization of planar two-dimensional （2D） photonic crystals （PhCs） made in silicon on insulator （SOI） wafers using ellipsometric or Fourier transformed infrared （FTIR） spectroscope. At large wavelengths, devices behave as homogeneous isotropic materials defined by an effective filling factor. The experimental results related to the PhC limited dimensions confirm this characterization.
文摘This paper presents a statement of the works performed in L.E.M.T.A by the members of the thermal and mechanical heterogeneous media research group during the last six years concerning the solving of coupled conductive and radiative heat transfers within a multilayer and semi-transparent“wall”.Out of the authors,this paper allows to take inspiration from the works of D.Maillet,M.Lazard and V.Manias[19,20,21].The aim of these works is to represent in a macroscopic way,with the minimum number of thermophysical parameters,the heat transfers in a plane system composed of semi-transparent media.The approach we propose is semi-analytic(Kernel substitution technique,Laplace transformation)and allow to obtain in the Laplace domain an analytical solution that can be easily used.This method can be applied in two main scopes of applications:the estimation of thermophysical properties(phononic conductivity,optical thickness,Planck number for instance)of semi-transparent materials(glasses,crystals,glass wool,semi-conductors,synthetic diamonds,vitroceramics and so on)and the modelling of processes with semitransparent walls(for instance bottles forming,flat glass production,drying of paper).The method will be first presented and validated and two examples of applications will be then given.This method can be applied to semitransparent walls that emit,absorb and scatter the radiant energy(participating medium).It appears from the principle of a Kernel substitution technique applied to the radiative flux expression and initially introduced by Lick[1]that allows to change the character of the governing heat equation from the integro-differential form to a purely differential one.In the case of limiting cases of purely scattering and purely absorbing media,the solution of the radiative transfer equation is exact.In the general case,we make a two-flux approximation.In all cases,we assume a linear transfer and use the Laplace transform.The method can be applied to grey or grey by bands media,with isotropic or anisotropic scattering.The advantage of the method is fast computational times for good precision.
