Objective To estimate the relationship between migration and HIV risky behavior when controlling for gender, age, and educational levels and to evaluate the gender differences in migration, HIV knowledge, and HIV risk...Objective To estimate the relationship between migration and HIV risky behavior when controlling for gender, age, and educational levels and to evaluate the gender differences in migration, HIV knowledge, and HIV risky behaviors among rural youth in China. Methods A cross-sectional, anonymous, investigative questionnaire for 1710 unmarried, out-of-school rural youth, aged between 15 and 24 years, was handed out in Gongzhuling county of Jilin province, China. Results 58.5% of participants had a history of migration, irrespective of gender. There were gender differences observed in other factors such as drug abuse（4.3% for males and 5.5% for females, P〈0.01）, multiple sexual partners（24.1% for males and 44.1% for females, P〈0.01）, and HIV knowledge rate（35.2% for males and 25.5% for females, P〈0.001）. While controlling for gender, age, and educational levels, the relationships between migration and drug abuse, selling sex, and non usage of condoms during last instance of sexual activity were found to be significant. The cases of premarital sex and multiple sexual partners were both not found to be related to migration. Conclusion Among rural youth, the HIV risky behavior such as drug abuse, selling sex, and lack of condom use, is significantly related to migration, while premarital sex and multiple sexual partners seem unrelated to migration.展开更多
We propose a catalysis-select migration driven evolution model of two-species（A-and B-species） aggregates,where one unit of species A migrates to species B under the catalysts of species C,while under the catalysts ...We propose a catalysis-select migration driven evolution model of two-species（A-and B-species） aggregates,where one unit of species A migrates to species B under the catalysts of species C,while under the catalysts of species D the reaction will become one unit of species B migrating to species A.Meanwhile the catalyst aggregates of species C perform self-coagulation,as do the species D aggregates.We study this catalysis-select migration driven kinetic aggregation phenomena using the generalized Smoluchowski rate equation approach with C species catalysis-select migration rate kernel K（k;i,j） = Kkij and D species catalysis-select migration rate kernel J（k;i,j） = Jkij.The kinetic evolution behaviour is found to be dominated by the competition between the catalysis-select immigration and emigration,in which the competition is between JD0 and KC0（D0 and C0 are the initial numbers of the monomers of species D and C,respectively）.When JD0 KC0 〉 0,the aggregate size distribution of species A satisfies the conventional scaling form and that of species B satisfies a modified scaling form.And in the case of JD0 KC0 〈 0,species A and B exchange their aggregate size distributions as in the above JD0 KC0 〉 0 case.展开更多
Motile cells of the green alga, Ulva fasciata respond to the quantity and quality of irradiance simultaneously. The specific responses of motile cell types (gametes and spores) by irradiance influence migration behavi...Motile cells of the green alga, Ulva fasciata respond to the quantity and quality of irradiance simultaneously. The specific responses of motile cell types (gametes and spores) by irradiance influence migration behavior in coastal water environment. Gametes maximally aggregated at the highest white light intensity (250 μmol·m-2·s-1), while spores maximally aggregated in the dark (0 μmol m-2·s-1) of this study. Gametes maximally aggregated in green irradiance over blue, red and dark while spore maximally aggregated in the dark. The results of quantity are spectral responses are likely to be underline the ecological success and physiological strategies in varied irradiance environments includes: 1) gametes respond to specific quantities and spectral irradiance;2) spores respond negatively to quantity and quality of irradiance to enhance the probability of finding substratum;and 3) populations of adults that come from these motile cells behaviors. The specific quantities and spectral qualities of irradiance responses show specific ecological migration that can be attributed to photosynthesis under limiting irradiance in coastal waters for the motile cells of U. fasciata.展开更多
We study the kinetic behavior of a two-species aggregation-migration model in which an irreversible aggregation occurs between any two clusters of the same species and a reversible migration occurs simultaneously betw...We study the kinetic behavior of a two-species aggregation-migration model in which an irreversible aggregation occurs between any two clusters of the same species and a reversible migration occurs simultaneously between two different species. For a simple model with constant aggregation rates and with the migration rates KA(i;j) =K'A (i;j) ∝ijv1 and KB(i; j) = K'B (i; j) ∝ ijv2, we find that the evolution behavior of the system depends crucially on the values of the indexes v1 and v2. The aggregate size distribution of either species obeys a conventional scaling law for most cases. Moreover, we also generalize the two-species system to the multi-species case and analyze its kinetic behavior under the symmetrical conditions.PACS numbers: 82.20.-w, 05.40.-a, 68.43.Jk, 89.75.展开更多
The fault system of Liaodong Bay developed extensively under the control of the Tanlu Fault. The fault system can be grouped into strike-slip faults of grade Ⅰ, trunk faults of grade Ⅱand branch faults （induced fau...The fault system of Liaodong Bay developed extensively under the control of the Tanlu Fault. The fault system can be grouped into strike-slip faults of grade Ⅰ, trunk faults of grade Ⅱand branch faults （induced faults） of grade Ⅲ respectively based on its developmental scale. The faults of grade Ⅰ and Ⅱwere deep, early and large while the faults of grade Ⅲwere shallow, late and small. The formation, evolution and distribution features played a significant role in controlling the migration of oil and gas in both horizontal and vertical directions. The fluid transfer in the fault system occurred in the process of faulting. The strike-slip and trunk faults moved actively forming predominant pathways for oil and gas migration. The branch faults, with weak activity, generally controlled the development of traps and were beneficial for the accumulation and preservation of oil and gas. The faults of grade Ⅰ and Ⅱ formed the major migration pathways for oil and gas, but their fault activity rates appeared to vary along their strikes. The zones with a relatively low fault activity rate might be favorable for oil and gas accumulation. When the activities of strike-slip, trunk, and branch faults came to a halt, the fault seal behavior had a vitally important effect on the accumulation of oil and gas. The controlling role of the fault over fluid distribution was further analyzed by calculating the fault activity quantitatively.展开更多
Territory and territorial behavior of the Common Coot（Fulica atra） were studied in two breeding sites,Anbanghe Nature Reserve and Daqing Longfeng wetland,in Heilongjiang Province,China from April to October in 2008 ...Territory and territorial behavior of the Common Coot（Fulica atra） were studied in two breeding sites,Anbanghe Nature Reserve and Daqing Longfeng wetland,in Heilongjiang Province,China from April to October in 2008 and 2009.In the breeding season,the breeding pairs occupied an area and protected it throughout the reproduction,and both interspecific and intraspecific conflicts were observed.Territory activities became severe since early May,the peak of territory behaviors appeared at late May,and then declined gradually.The territorial activities level was higher than that in the nest building period than in the laying and incubation periods.The most adopted behavioral model was expelling,which was the least energy cost.The degree of territorial behavior tended to be descended since the development of breeding phase.The territory size differed from 1 333 m2 to above 5 000 m2.Wintering population was observed in Poyang Lake of Jiangxi Province.The coots gathered in the open water;however,there was no territory behavior both in the interspecies and intraspecies in wintering sites.The hypotheses why there was territory behaviors for coots both in the interspecies and intraspecies were also discussed.展开更多
Background: Departure decisions and behaviors of migratory birds at stopover sites are expected to maximize fit?ness by trade?offs among avoiding predators, optimizing refueling(energy) capacity, and matching other li...Background: Departure decisions and behaviors of migratory birds at stopover sites are expected to maximize fit?ness by trade?offs among avoiding predators, optimizing refueling(energy) capacity, and matching other life?history events. We predict that species with different body sizes and migratory destinations will exhibit different behaviors when departing from the same stopover site. We also predict that with strong time constraint at the final pre?breed?ing stopover site, departure decisions may be less sensitive to exogenous factors, such as wind condition, compared to other stopover or nonbreeding sites.Methods: We recorded migratory departures of four shorebird species, i.e. Eurasian Curlew(Numenius arquata), Bar?tailed Godwit(Limosa lapponica), Great Knot(Calidris tenuirostris), and Grey Plover(Pluvialis squatarola), at Yaluji?ang Estuary Wetlands in China, a final pre?breeding stopover site in the northern Yellow Sea, from 2011 to 2014. We compared flock sizes, departure time and departure directions between species, and investigated the effects of tide and weather conditions(rain and ground wind speed and direction) on the departure decision of shorebirds.Results: We found that larger species departed in smaller flocks and were more variable in daily departure time. Departure trajectory of all four species appeared to be influenced by coastal topography. With the east–west coast?line and intertidal mudflat on the south, birds exhibited westward or eastward deflection from the shortest migra?tory routes. Bar?tailed Godwit was the only species that deviated to the southeast and did not climb over the land. Birds avoided departure during precipitation, while their departure was not related to ground wind benefit or tidal condition.Conclusions: Body size among species, which influences their vulnerability to predators, might be important in shaping shorebird departure strategies. Diverse departure directions could be the result of different wind use tac?tics in climbing stage. Narrow optimal time window of breeding might lead to reduced flexibility in departure date at a final pre?breeding site. Both endogenous and exogenous are important in shaping departure behaviors and decisions.展开更多
Cell migration in anisotropic microenvironment plays an important role in the development of normal tissues and organs as well as neoplasm progression,e.g.,osteogenic differentiation of embryonic stem cells was facili...Cell migration in anisotropic microenvironment plays an important role in the development of normal tissues and organs as well as neoplasm progression,e.g.,osteogenic differentiation of embryonic stem cells was facilitated on stiffer substrates,indicating that the mechanical signals greatly affect both early and terminal differentiation of embryonic stem cells.However,the effect of anisotropy on cell migration dynamics,in particular,in terms of acceleration profiles which is important for recognizing dynamics modes of cell migration and analyzing the regulation mechanisms of microenvironment in mechanical signal transmission,has not been systematically investigated.In this work,we firstly rigorously investigate and quantify the differences between persistent random walk and anisotropic persistent random walk models based on the analysis of cell migration trajectories and velocity auto-covariance function,both qualitatively and quantitatively.Secondly,we introduce the concepts of positive and negative anisotropy based on the motility parameters to study the effect of anisotropy on acceleration profiles,especially the nonlinear decrease and non-monotonic behaviors.We particularly elaborate and discuss the mechanisms,and physical insights of non-monotonic behaviors in the case of positive anisotropy,focusing on the force exerted on migrating cells.Finally,we analyze two types of in vitro cell migration experiments and verify the universality of nonlinear decrease and the consistence of non-monotonic behaviors with numerical results.We conclude that the anisotropy of microenvironment is the cause of the non-monotonic and nonlinear dynamics,and the anisotropic persistent random walk can be as a suitable tool to analyze in vitro cell migration with different combinations of motility parameters.Our analysis provides new insights into the dynamics of cell migration in complex microenvironment,which also has implications in tissue engineering and cancer research.展开更多
We propose a two-species monomer migration-annihilation model, in which monomer migration reactions occur between any two aggregates of the same species and monomer annihilation reactions occur between two different s...We propose a two-species monomer migration-annihilation model, in which monomer migration reactions occur between any two aggregates of the same species and monomer annihilation reactions occur between two different species. Based on the mean-field rate equations, we investigate the evolution behaviors of the processes. For the case with an annihilation rate kernel proportional to the sizes of the reactants, the aggregation size distribution of either species approaches the modified scaling form in the symmetrical initial case, while for the asymmetrical initial case the heavy species with a large initial data scales according to the conventional form and the light one does not scale. Moreover,at most one species can survive finally. For the case with aconstant annihilation rate kernel, both species may scale according to the conventional scaling law in the symmetrical case and survive together at the end.展开更多
通过微细观结构分析、低场核磁共振量化研究,科学、准确地描述膏体跨尺度颗粒群存在形态与水分赋存状态,并基于有限元和离散元耦合数值分析方法分析了泵压扰动下膏体颗粒流态演化规律.研究发现,膏体料浆中的吸附水、间隙水和弱自由水存...通过微细观结构分析、低场核磁共振量化研究,科学、准确地描述膏体跨尺度颗粒群存在形态与水分赋存状态,并基于有限元和离散元耦合数值分析方法分析了泵压扰动下膏体颗粒流态演化规律.研究发现,膏体料浆中的吸附水、间隙水和弱自由水存在动态连通与转化行为,并主要以吸附水形式存在,低场核磁共振技术(Low-field nuclear magnetic resonance,LF-NMR)弛豫强度与吸附水峰面积非线性增强,与料浆的流动表现出显著的正相关性.液网结构与絮网结构反映了导水通道的活跃性与力链结构的强度,共同组成了膏体稳定性与流动性的双支撑骨架结构.通过Fluent-EDEM软件耦合模拟,分析了脉冲泵压环境颗粒运动行为,在速度差的影响下高、低流速颗粒冲击扰动加剧,力链接触作用增强,流态均匀性和整体颗粒运动稳定性可有效提高.展开更多
基金supported by the 2006 Chinese National AIDS Prevention Social Mobilization Project 06-I-37
文摘Objective To estimate the relationship between migration and HIV risky behavior when controlling for gender, age, and educational levels and to evaluate the gender differences in migration, HIV knowledge, and HIV risky behaviors among rural youth in China. Methods A cross-sectional, anonymous, investigative questionnaire for 1710 unmarried, out-of-school rural youth, aged between 15 and 24 years, was handed out in Gongzhuling county of Jilin province, China. Results 58.5% of participants had a history of migration, irrespective of gender. There were gender differences observed in other factors such as drug abuse（4.3% for males and 5.5% for females, P〈0.01）, multiple sexual partners（24.1% for males and 44.1% for females, P〈0.01）, and HIV knowledge rate（35.2% for males and 25.5% for females, P〈0.001）. While controlling for gender, age, and educational levels, the relationships between migration and drug abuse, selling sex, and non usage of condoms during last instance of sexual activity were found to be significant. The cases of premarital sex and multiple sexual partners were both not found to be related to migration. Conclusion Among rural youth, the HIV risky behavior such as drug abuse, selling sex, and lack of condom use, is significantly related to migration, while premarital sex and multiple sexual partners seem unrelated to migration.
基金Project supported by the National Natural Science Foundation of China (Grant Nos. 10875086 and 10775104)
文摘We propose a catalysis-select migration driven evolution model of two-species（A-and B-species） aggregates,where one unit of species A migrates to species B under the catalysts of species C,while under the catalysts of species D the reaction will become one unit of species B migrating to species A.Meanwhile the catalyst aggregates of species C perform self-coagulation,as do the species D aggregates.We study this catalysis-select migration driven kinetic aggregation phenomena using the generalized Smoluchowski rate equation approach with C species catalysis-select migration rate kernel K（k;i,j） = Kkij and D species catalysis-select migration rate kernel J（k;i,j） = Jkij.The kinetic evolution behaviour is found to be dominated by the competition between the catalysis-select immigration and emigration,in which the competition is between JD0 and KC0（D0 and C0 are the initial numbers of the monomers of species D and C,respectively）.When JD0 KC0 〉 0,the aggregate size distribution of species A satisfies the conventional scaling form and that of species B satisfies a modified scaling form.And in the case of JD0 KC0 〈 0,species A and B exchange their aggregate size distributions as in the above JD0 KC0 〉 0 case.
文摘Motile cells of the green alga, Ulva fasciata respond to the quantity and quality of irradiance simultaneously. The specific responses of motile cell types (gametes and spores) by irradiance influence migration behavior in coastal water environment. Gametes maximally aggregated at the highest white light intensity (250 μmol·m-2·s-1), while spores maximally aggregated in the dark (0 μmol m-2·s-1) of this study. Gametes maximally aggregated in green irradiance over blue, red and dark while spore maximally aggregated in the dark. The results of quantity are spectral responses are likely to be underline the ecological success and physiological strategies in varied irradiance environments includes: 1) gametes respond to specific quantities and spectral irradiance;2) spores respond negatively to quantity and quality of irradiance to enhance the probability of finding substratum;and 3) populations of adults that come from these motile cells behaviors. The specific quantities and spectral qualities of irradiance responses show specific ecological migration that can be attributed to photosynthesis under limiting irradiance in coastal waters for the motile cells of U. fasciata.
文摘We study the kinetic behavior of a two-species aggregation-migration model in which an irreversible aggregation occurs between any two clusters of the same species and a reversible migration occurs simultaneously between two different species. For a simple model with constant aggregation rates and with the migration rates KA(i;j) =K'A (i;j) ∝ijv1 and KB(i; j) = K'B (i; j) ∝ ijv2, we find that the evolution behavior of the system depends crucially on the values of the indexes v1 and v2. The aggregate size distribution of either species obeys a conventional scaling law for most cases. Moreover, we also generalize the two-species system to the multi-species case and analyze its kinetic behavior under the symmetrical conditions.PACS numbers: 82.20.-w, 05.40.-a, 68.43.Jk, 89.75.
文摘The fault system of Liaodong Bay developed extensively under the control of the Tanlu Fault. The fault system can be grouped into strike-slip faults of grade Ⅰ, trunk faults of grade Ⅱand branch faults （induced faults） of grade Ⅲ respectively based on its developmental scale. The faults of grade Ⅰ and Ⅱwere deep, early and large while the faults of grade Ⅲwere shallow, late and small. The formation, evolution and distribution features played a significant role in controlling the migration of oil and gas in both horizontal and vertical directions. The fluid transfer in the fault system occurred in the process of faulting. The strike-slip and trunk faults moved actively forming predominant pathways for oil and gas migration. The branch faults, with weak activity, generally controlled the development of traps and were beneficial for the accumulation and preservation of oil and gas. The faults of grade Ⅰ and Ⅱ formed the major migration pathways for oil and gas, but their fault activity rates appeared to vary along their strikes. The zones with a relatively low fault activity rate might be favorable for oil and gas accumulation. When the activities of strike-slip, trunk, and branch faults came to a halt, the fault seal behavior had a vitally important effect on the accumulation of oil and gas. The controlling role of the fault over fluid distribution was further analyzed by calculating the fault activity quantitatively.
基金supported by Natural Science Foundation of Heilongjiang Province (C201036)
文摘Territory and territorial behavior of the Common Coot（Fulica atra） were studied in two breeding sites,Anbanghe Nature Reserve and Daqing Longfeng wetland,in Heilongjiang Province,China from April to October in 2008 and 2009.In the breeding season,the breeding pairs occupied an area and protected it throughout the reproduction,and both interspecific and intraspecific conflicts were observed.Territory activities became severe since early May,the peak of territory behaviors appeared at late May,and then declined gradually.The territorial activities level was higher than that in the nest building period than in the laying and incubation periods.The most adopted behavioral model was expelling,which was the least energy cost.The degree of territorial behavior tended to be descended since the development of breeding phase.The territory size differed from 1 333 m2 to above 5 000 m2.Wintering population was observed in Poyang Lake of Jiangxi Province.The coots gathered in the open water;however,there was no territory behavior both in the interspecies and intraspecies in wintering sites.The hypotheses why there was territory behaviors for coots both in the interspecies and intraspecies were also discussed.
基金financially supported by the National Natural Science Foundation of China(31071939,31572280,and 31772467)
文摘Background: Departure decisions and behaviors of migratory birds at stopover sites are expected to maximize fit?ness by trade?offs among avoiding predators, optimizing refueling(energy) capacity, and matching other life?history events. We predict that species with different body sizes and migratory destinations will exhibit different behaviors when departing from the same stopover site. We also predict that with strong time constraint at the final pre?breed?ing stopover site, departure decisions may be less sensitive to exogenous factors, such as wind condition, compared to other stopover or nonbreeding sites.Methods: We recorded migratory departures of four shorebird species, i.e. Eurasian Curlew(Numenius arquata), Bar?tailed Godwit(Limosa lapponica), Great Knot(Calidris tenuirostris), and Grey Plover(Pluvialis squatarola), at Yaluji?ang Estuary Wetlands in China, a final pre?breeding stopover site in the northern Yellow Sea, from 2011 to 2014. We compared flock sizes, departure time and departure directions between species, and investigated the effects of tide and weather conditions(rain and ground wind speed and direction) on the departure decision of shorebirds.Results: We found that larger species departed in smaller flocks and were more variable in daily departure time. Departure trajectory of all four species appeared to be influenced by coastal topography. With the east–west coast?line and intertidal mudflat on the south, birds exhibited westward or eastward deflection from the shortest migra?tory routes. Bar?tailed Godwit was the only species that deviated to the southeast and did not climb over the land. Birds avoided departure during precipitation, while their departure was not related to ground wind benefit or tidal condition.Conclusions: Body size among species, which influences their vulnerability to predators, might be important in shaping shorebird departure strategies. Diverse departure directions could be the result of different wind use tac?tics in climbing stage. Narrow optimal time window of breeding might lead to reduced flexibility in departure date at a final pre?breeding site. Both endogenous and exogenous are important in shaping departure behaviors and decisions.
基金Project supported by the National Natural Science Foundation of China(Grant Nos.11974066,11674043,11675134,and 11874310)the Natural Science Foundation of Chongqing,China(Grant Nos.cstc2019jcyj-msxmX0477 and cstc2018jcyjA3679)the Capital Health Development Research Project,China(Grant No.2020-2-2072).
文摘Cell migration in anisotropic microenvironment plays an important role in the development of normal tissues and organs as well as neoplasm progression,e.g.,osteogenic differentiation of embryonic stem cells was facilitated on stiffer substrates,indicating that the mechanical signals greatly affect both early and terminal differentiation of embryonic stem cells.However,the effect of anisotropy on cell migration dynamics,in particular,in terms of acceleration profiles which is important for recognizing dynamics modes of cell migration and analyzing the regulation mechanisms of microenvironment in mechanical signal transmission,has not been systematically investigated.In this work,we firstly rigorously investigate and quantify the differences between persistent random walk and anisotropic persistent random walk models based on the analysis of cell migration trajectories and velocity auto-covariance function,both qualitatively and quantitatively.Secondly,we introduce the concepts of positive and negative anisotropy based on the motility parameters to study the effect of anisotropy on acceleration profiles,especially the nonlinear decrease and non-monotonic behaviors.We particularly elaborate and discuss the mechanisms,and physical insights of non-monotonic behaviors in the case of positive anisotropy,focusing on the force exerted on migrating cells.Finally,we analyze two types of in vitro cell migration experiments and verify the universality of nonlinear decrease and the consistence of non-monotonic behaviors with numerical results.We conclude that the anisotropy of microenvironment is the cause of the non-monotonic and nonlinear dynamics,and the anisotropic persistent random walk can be as a suitable tool to analyze in vitro cell migration with different combinations of motility parameters.Our analysis provides new insights into the dynamics of cell migration in complex microenvironment,which also has implications in tissue engineering and cancer research.
文摘We propose a two-species monomer migration-annihilation model, in which monomer migration reactions occur between any two aggregates of the same species and monomer annihilation reactions occur between two different species. Based on the mean-field rate equations, we investigate the evolution behaviors of the processes. For the case with an annihilation rate kernel proportional to the sizes of the reactants, the aggregation size distribution of either species approaches the modified scaling form in the symmetrical initial case, while for the asymmetrical initial case the heavy species with a large initial data scales according to the conventional form and the light one does not scale. Moreover,at most one species can survive finally. For the case with aconstant annihilation rate kernel, both species may scale according to the conventional scaling law in the symmetrical case and survive together at the end.
文摘通过微细观结构分析、低场核磁共振量化研究,科学、准确地描述膏体跨尺度颗粒群存在形态与水分赋存状态,并基于有限元和离散元耦合数值分析方法分析了泵压扰动下膏体颗粒流态演化规律.研究发现,膏体料浆中的吸附水、间隙水和弱自由水存在动态连通与转化行为,并主要以吸附水形式存在,低场核磁共振技术(Low-field nuclear magnetic resonance,LF-NMR)弛豫强度与吸附水峰面积非线性增强,与料浆的流动表现出显著的正相关性.液网结构与絮网结构反映了导水通道的活跃性与力链结构的强度,共同组成了膏体稳定性与流动性的双支撑骨架结构.通过Fluent-EDEM软件耦合模拟,分析了脉冲泵压环境颗粒运动行为,在速度差的影响下高、低流速颗粒冲击扰动加剧,力链接触作用增强,流态均匀性和整体颗粒运动稳定性可有效提高.
