The capability of neurons to discriminate between intensity of external stimulus is measured by its dynamic range.A larger dynamic range indicates a greater probability of neuronal survival.In this study,the potential...The capability of neurons to discriminate between intensity of external stimulus is measured by its dynamic range.A larger dynamic range indicates a greater probability of neuronal survival.In this study,the potential roles of adaptation mechanisms（ion currents） in modulating neuronal dynamic range were numerically investigated.Based on the adaptive exponential integrate-and-fire model,which includes two different adaptation mechanisms,i.e.subthreshold and suprathreshold（spike-triggered） adaptation,our results reveal that the two adaptation mechanisms exhibit rather different roles in regulating neuronal dynamic range.Specifically,subthreshold adaptation acts as a negative factor that observably decreases the neuronal dynamic range,while suprathreshold adaptation has little influence on the neuronal dynamic range.Moreover,when stochastic noise was introduced into the adaptation mechanisms,the dynamic range was apparently enhanced,regardless of what state the neuron was in,e.g.adaptive or non-adaptive.Our model results suggested that the neuronal dynamic range can be differentially modulated by different adaptation mechanisms.Additionally,noise was a non-ignorable factor,which could effectively modulate the neuronal dynamic range.展开更多
研究了一种用作自适应纤维——氨纶的蠕变行为。首先将聚四氢呋喃醚二醇与4,4′-二苯基甲烷-二异氰酸酯按物质的量之比1.0︰1.6反应形成预聚体,再添加溶剂N,N-二甲基乙酰胺,制得浓度为35%的预聚体溶液,然后用乙二胺进行扩链反应,制得纺...研究了一种用作自适应纤维——氨纶的蠕变行为。首先将聚四氢呋喃醚二醇与4,4′-二苯基甲烷-二异氰酸酯按物质的量之比1.0︰1.6反应形成预聚体,再添加溶剂N,N-二甲基乙酰胺,制得浓度为35%的预聚体溶液,然后用乙二胺进行扩链反应,制得纺丝原液,经喷丝板喷出的原液细流在风量为690 m3/h、温度为244℃的热甬道中干燥,以1.00︰1.10的牵伸比纺制出线密度为11.67 tex的干纺氨纶样品。在自适应纤维氨纶的实际使用条件(25℃和小应力)下,使用动态力学分析仪在拉伸蠕变模式下测试了该氨纶样品在不同时间的应变。然后采用2类广义Kelvin模型、分数指数模型和Findley power law模型对上述实验数据进行拟合,结果表明,分数指数模型能很好地反映氨纶的应变随不同应力和不同时间的变化规律,并建立了氨纶拉伸蠕变模型的数学表达式。由表达式计算的不同应力水平时,不同时间的应变值与相应的实测值之间的最大相对误差只有5%。因此,该表达式能较好地预测氨纶材料的蠕变行为。展开更多
基金supported by a grant from Beijing Municipal Commission of Science and Technology of China,No.Z151100000915070
文摘The capability of neurons to discriminate between intensity of external stimulus is measured by its dynamic range.A larger dynamic range indicates a greater probability of neuronal survival.In this study,the potential roles of adaptation mechanisms（ion currents） in modulating neuronal dynamic range were numerically investigated.Based on the adaptive exponential integrate-and-fire model,which includes two different adaptation mechanisms,i.e.subthreshold and suprathreshold（spike-triggered） adaptation,our results reveal that the two adaptation mechanisms exhibit rather different roles in regulating neuronal dynamic range.Specifically,subthreshold adaptation acts as a negative factor that observably decreases the neuronal dynamic range,while suprathreshold adaptation has little influence on the neuronal dynamic range.Moreover,when stochastic noise was introduced into the adaptation mechanisms,the dynamic range was apparently enhanced,regardless of what state the neuron was in,e.g.adaptive or non-adaptive.Our model results suggested that the neuronal dynamic range can be differentially modulated by different adaptation mechanisms.Additionally,noise was a non-ignorable factor,which could effectively modulate the neuronal dynamic range.
文摘研究了一种用作自适应纤维——氨纶的蠕变行为。首先将聚四氢呋喃醚二醇与4,4′-二苯基甲烷-二异氰酸酯按物质的量之比1.0︰1.6反应形成预聚体,再添加溶剂N,N-二甲基乙酰胺,制得浓度为35%的预聚体溶液,然后用乙二胺进行扩链反应,制得纺丝原液,经喷丝板喷出的原液细流在风量为690 m3/h、温度为244℃的热甬道中干燥,以1.00︰1.10的牵伸比纺制出线密度为11.67 tex的干纺氨纶样品。在自适应纤维氨纶的实际使用条件(25℃和小应力)下,使用动态力学分析仪在拉伸蠕变模式下测试了该氨纶样品在不同时间的应变。然后采用2类广义Kelvin模型、分数指数模型和Findley power law模型对上述实验数据进行拟合,结果表明,分数指数模型能很好地反映氨纶的应变随不同应力和不同时间的变化规律,并建立了氨纶拉伸蠕变模型的数学表达式。由表达式计算的不同应力水平时,不同时间的应变值与相应的实测值之间的最大相对误差只有5%。因此,该表达式能较好地预测氨纶材料的蠕变行为。
