Topography and space are two important factors determining plant species assemblages in forest communities.Quantification of the contribution of these two factors in determining species distribution helps us to evalua...Topography and space are two important factors determining plant species assemblages in forest communities.Quantification of the contribution of these two factors in determining species distribution helps us to evaluate their relative importance in determining species assemblages.This study aims to disentangle the effect of topography and space on the distributions of 14 dominant species in a subtropical mixed forest.Spearman correlation analysis and the torustranslation test were used to test the species–habitat associations.Variation partitioning was used to quantify the relative contributions of topography and space at three sampling scales and three life stages.Correlation analyses and torus-translation tests showed species abundance was mostly correlated with topographic wetness index,vertical distance from the channel network and convexity.Variation partitioning showed that pure topography,pure space and spatially structured topography explained about 2.1 %,41.2 % and 13.8 %of the variation in species distributions,respectively.For nine species,total topography fractions peaked in 20 m quadrats.For ten species,the pure space fractions peaked in 50 m quadrats.For many species,the total topography fraction andthe pure space fraction were larger for the most abundant life stages,which reflected the importance of sampling effect.However,some cases did not follow this trend suggesting that the effects of ecological processes such as habitat filtering,density dependence or dispersal limitation may exceed the sampling effects.In conclusion,we found that spatially structured topography and pure space primarily shaped the distribution of dominant tree species.Furthermore,their effects were both scale- and life stage-dependent.展开更多
Aims seedlings are vulnerable to many kinds of fatal abiotic and biotic agents,and examining the causes of seedling dynamics can help understand mechanisms of species coexistence.To disentangle the relative importance...Aims seedlings are vulnerable to many kinds of fatal abiotic and biotic agents,and examining the causes of seedling dynamics can help understand mechanisms of species coexistence.To disentangle the relative importance of neighborhood densities,habitat factors and phylogenetic relatedness on focal seedling survival,we monitored the survival of 5306 seedlings of 104 species>15 months.We address the following questions:(i)How do neighborhood densities,habitat variables and phylogenetic relatedness affect seedling survival?What is the relative importance of conspecific densities,habitat variables and phylogenetic relatedness to seedling survival?(ii)Does the importance of the neighborhood densities,habitat variables and phylogenetic relatedness vary among growth forms,leaf habits or dispersal modes?specially,does the conspecific negative density dependence inhibit tree and decidu-ous seedlings more compared with shrub and evergreen species?Does density dependence affect the wind and animal-dispersed species equally?Methods We established 135 census stations to monitor seedling dynamics in a 25-ha subtropical forest plot in central China.Conspecific and heterospecific seedling density in the 1-m2 seedling plot and adult basal area within a 20-m radius provided neighborhood density var-iables.mean elevation,convexity and aspect of every 5-×5-m grid with seedling plots were used to quantify habitat characteristics.We calculated the relative average phylodiversity between focal seed-ling and heterospecific neighbors to quantify the species related-ness in the neighborhood.Eight candidate generalized linear mixed models with binominal error distribution were used to compare the relative importance of these variables to seedling survival.akaike’s information criteria were used to identify the most parsimonious models.Important Findingsat the community level,both the neighborhood densities and phylogenetic relatedness were important to seedling survival.We found negative effects of increasing conspecific seedlings,which 展开更多
To determine whether repetitive transcranial magnetic stimulation(rTMS)of the visual cortex(VC)provides effective and welltolerated treatment and whether magnetic resonance imaging(MRI)measures functional change of th...To determine whether repetitive transcranial magnetic stimulation(rTMS)of the visual cortex(VC)provides effective and welltolerated treatment and whether magnetic resonance imaging(MRI)measures functional change of the VC as a biomarker of therapeutic effect in major depressive disorder(MDD),we performed a sham-controlled,double-blind,randomized,three-arm VC rTMS treatment study in 74 MDD patients.Neuronavigated rTMS(10 Hz,90%of resting motor threshold,1,600 pulses over20 min twice per day)was performed over the VC for five days.Clinical outcome was measured by Hamilton Depression Rating Scale(HAMD-24)at days 0,1,3,5 and after terminating rTMS,with follow-up at four weeks.MRI was measured at days 0 and5.The individualized group exhibited the greatest change in HAMD-24 scores after VC rTMS for 5 days(F=5.53,P=0.005),which were maintained during follow-up period(F=4.22,P=0.016).All patients reported good tolerance.Changes in VC taskrelated functional MRI correlated with symptomatic reduction in the individualized group.Treatment reduced the initially abnormal increase in resting state functional connectivity from the VC to the pre/subgenual anterior cingulate cortex at day 5,especially in the individualized group.We demonstrated therapeutic potential and good tolerance of VC rTMS in MDD patients,indicated by biomarkers of f MRI measurement.展开更多
For the abnormal ice condition in 2009-2010 winter, sea ice samples were collected in a tide ditch outside a port in the east coast of Liaodong Bay, and ice specimens were prepared. Experimental study was carried out ...For the abnormal ice condition in 2009-2010 winter, sea ice samples were collected in a tide ditch outside a port in the east coast of Liaodong Bay, and ice specimens were prepared. Experimental study was carried out with a temperature-control precision of 0.1℃, and 117 columnar-grained ice specimens were loaded along the direction parallel to ice surface under different test temperatures （-4, -7, -10, -13, -16℃） and strain rates ranging from 10^-6 to 10^-2 s^-1 within which the ductile region, duetile-brittle transition and brittle region are contained. The uniaxial compressive strengths, density and salinity of the ice specmens were measured. The results support the curved-surface relationship between the uniaxial compressive strength and porosity within a wide range of strain rate. The curved-surface relationship gives a quantitative description about the variations of the mechanical behavior transition point with ice porosity, and supplies a uniform mathematical representation of uniaxial compressive strength under different failure modes. Besides, it is deduced that abnormal ice condition in 2009-2010 winter will not result in a change of the uniaxial compressive strength of sea ice in Bohai Sea.展开更多
基金supported by the National Natural Science Foundation of China(31270562 and 31200329)the Chinese Forest Biodiversity Monitoring Network(29200931131101919)
文摘Topography and space are two important factors determining plant species assemblages in forest communities.Quantification of the contribution of these two factors in determining species distribution helps us to evaluate their relative importance in determining species assemblages.This study aims to disentangle the effect of topography and space on the distributions of 14 dominant species in a subtropical mixed forest.Spearman correlation analysis and the torustranslation test were used to test the species–habitat associations.Variation partitioning was used to quantify the relative contributions of topography and space at three sampling scales and three life stages.Correlation analyses and torus-translation tests showed species abundance was mostly correlated with topographic wetness index,vertical distance from the channel network and convexity.Variation partitioning showed that pure topography,pure space and spatially structured topography explained about 2.1 %,41.2 % and 13.8 %of the variation in species distributions,respectively.For nine species,total topography fractions peaked in 20 m quadrats.For ten species,the pure space fractions peaked in 50 m quadrats.For many species,the total topography fraction andthe pure space fraction were larger for the most abundant life stages,which reflected the importance of sampling effect.However,some cases did not follow this trend suggesting that the effects of ecological processes such as habitat filtering,density dependence or dispersal limitation may exceed the sampling effects.In conclusion,we found that spatially structured topography and pure space primarily shaped the distribution of dominant tree species.Furthermore,their effects were both scale- and life stage-dependent.
基金National Natural Science Foundation of China(31070465 and 31200329)Chinese Forest Biodiversity Monitoring Network(29200931131101919).
文摘Aims seedlings are vulnerable to many kinds of fatal abiotic and biotic agents,and examining the causes of seedling dynamics can help understand mechanisms of species coexistence.To disentangle the relative importance of neighborhood densities,habitat factors and phylogenetic relatedness on focal seedling survival,we monitored the survival of 5306 seedlings of 104 species>15 months.We address the following questions:(i)How do neighborhood densities,habitat variables and phylogenetic relatedness affect seedling survival?What is the relative importance of conspecific densities,habitat variables and phylogenetic relatedness to seedling survival?(ii)Does the importance of the neighborhood densities,habitat variables and phylogenetic relatedness vary among growth forms,leaf habits or dispersal modes?specially,does the conspecific negative density dependence inhibit tree and decidu-ous seedlings more compared with shrub and evergreen species?Does density dependence affect the wind and animal-dispersed species equally?Methods We established 135 census stations to monitor seedling dynamics in a 25-ha subtropical forest plot in central China.Conspecific and heterospecific seedling density in the 1-m2 seedling plot and adult basal area within a 20-m radius provided neighborhood density var-iables.mean elevation,convexity and aspect of every 5-×5-m grid with seedling plots were used to quantify habitat characteristics.We calculated the relative average phylodiversity between focal seed-ling and heterospecific neighbors to quantify the species related-ness in the neighborhood.Eight candidate generalized linear mixed models with binominal error distribution were used to compare the relative importance of these variables to seedling survival.akaike’s information criteria were used to identify the most parsimonious models.Important Findingsat the community level,both the neighborhood densities and phylogenetic relatedness were important to seedling survival.We found negative effects of increasing conspecific seedlings,which
基金supported by grants from the National Key Research and Development Program of China(2016YFC1306700 to ZJZ,2016YFC1306704 to HXZ)the National Natural Science Key Foundation of China(81830040 to ZJZ)+2 种基金Science and Technology Program of Guangdong(2018B030334001 to ZJZ)Program of Excellent Talents in Medical Science of Jiangsu Province(JCRCA2016006 to ZJZ)the Program for Innovative Research Team in Science and Technology in University of Henan Province(18IRTSTHN025 to HXZ)。
文摘To determine whether repetitive transcranial magnetic stimulation(rTMS)of the visual cortex(VC)provides effective and welltolerated treatment and whether magnetic resonance imaging(MRI)measures functional change of the VC as a biomarker of therapeutic effect in major depressive disorder(MDD),we performed a sham-controlled,double-blind,randomized,three-arm VC rTMS treatment study in 74 MDD patients.Neuronavigated rTMS(10 Hz,90%of resting motor threshold,1,600 pulses over20 min twice per day)was performed over the VC for five days.Clinical outcome was measured by Hamilton Depression Rating Scale(HAMD-24)at days 0,1,3,5 and after terminating rTMS,with follow-up at four weeks.MRI was measured at days 0 and5.The individualized group exhibited the greatest change in HAMD-24 scores after VC rTMS for 5 days(F=5.53,P=0.005),which were maintained during follow-up period(F=4.22,P=0.016).All patients reported good tolerance.Changes in VC taskrelated functional MRI correlated with symptomatic reduction in the individualized group.Treatment reduced the initially abnormal increase in resting state functional connectivity from the VC to the pre/subgenual anterior cingulate cortex at day 5,especially in the individualized group.We demonstrated therapeutic potential and good tolerance of VC rTMS in MDD patients,indicated by biomarkers of f MRI measurement.
基金supported by the National Natural Science Foundation of China(Grant Nos.50921001,50879008)State Key Laboratory of Fro-zen Soil Engineering(Grant No.SKLFSE200904)+1 种基金Vilho,Yrj and Kalle Visl Fund of the Finnish Academy of Sciences and Lettersthe Norwegian Research Council Project AMORA(Grant No.193592/S30)
文摘For the abnormal ice condition in 2009-2010 winter, sea ice samples were collected in a tide ditch outside a port in the east coast of Liaodong Bay, and ice specimens were prepared. Experimental study was carried out with a temperature-control precision of 0.1℃, and 117 columnar-grained ice specimens were loaded along the direction parallel to ice surface under different test temperatures （-4, -7, -10, -13, -16℃） and strain rates ranging from 10^-6 to 10^-2 s^-1 within which the ductile region, duetile-brittle transition and brittle region are contained. The uniaxial compressive strengths, density and salinity of the ice specmens were measured. The results support the curved-surface relationship between the uniaxial compressive strength and porosity within a wide range of strain rate. The curved-surface relationship gives a quantitative description about the variations of the mechanical behavior transition point with ice porosity, and supplies a uniform mathematical representation of uniaxial compressive strength under different failure modes. Besides, it is deduced that abnormal ice condition in 2009-2010 winter will not result in a change of the uniaxial compressive strength of sea ice in Bohai Sea.
