The miniaturization and high integration of devices demand significant thermal management materials.Current technologies for the thermal management of electronics show some limitations in the case of multiple chip arr...The miniaturization and high integration of devices demand significant thermal management materials.Current technologies for the thermal management of electronics show some limitations in the case of multiple chip arrays.A device in multiple chip array is affected by heat from adjacent devices,along with thermal conductive composite.To address this problem,we present a nano composite of aligned boron nitride(BN)nanosheet islands with porous polydimethylsiloxane(PDMS)foam to have mechanical stability and non-thermal interference.The islands of tetrahedrally-structured BN in the composite have a high thermal conductivity of 1.219 W·m^(-1)·K^(-1) in the through-plane direction(11.234W·m^(-1)·K^(-1)in the in-plane direction)with 16 wt.%loading of BN.On the other hand,porous PDMS foam has a low thermal conductivity of 0.0328W·m^(-1)·K^(-1) in the through-plane direction at 70%porosity.Heat pathways are then formed only in the structured BN islands of the composite.The porous PDMS foam can be applied as a thermal barrier between structured BN islands to inhibit thermal interference in multiple device arrays.Furthermore,this composite can maintain selective thermal dissipation performance with 70%tensile strain.Another beauty of the work is that it could have guided heat dissipation by assembling of multiple layers which have high vertical thermal conductive islands,while inhibiting thermal interference.The selective heat dissipating composite can be applied as a heatsink for multiple chip arrays electronics.展开更多
In doubly-selective fading wireless channel, the conventional orthogonal frequency division multi-plexing （OFDM） receivers for inter-cartier interference （ICI） compensation require extensive computations. To obtai...In doubly-selective fading wireless channel, the conventional orthogonal frequency division multi-plexing （OFDM） receivers for inter-cartier interference （ICI） compensation require extensive computations. To obtain an effective balance between performance and complexity, the whole channel response matrix was decomposed into a sequence of submatrix, and then a novel equalizer based on minimum mean square error （MMSE） criterion was presented to combat the ICI. Furthermore, a simple ordering-based decision-feedback equalizer （DFE） Was derived to exploit the temperal diversity gain offered by mobile channels. Numerical studies illustrate that although the MMSE equalizer still suffers from error floor, whereas the DICE equalizer exhibits significant performance improvement. The advantage of the proposed scheme indicates its potential applications in the future broadband wireless systems.展开更多
Selective attention has been viewed as a dual- process mechanism, that is, exciting targets and inhibiting distractors. Most early studies concentrated mainly on the target-excitation, whereas recent investigations be...Selective attention has been viewed as a dual- process mechanism, that is, exciting targets and inhibiting distractors. Most early studies concentrated mainly on the target-excitation, whereas recent investigations began to pay more attention to the inhibitory selective attention mecha-nism. A measure named negative priming (NP) was exten-sively employed to probe into the inhibitory processes. The Houghton and Tipper Model put forward a notion: the inhi-bition that feeds back to the distractor is reactive. That means, the level of inhibition is determined by the activation state of the distractor. Distractors that are more salient and intrude into the control of action receive greater inhibitory feedbacks than less salient distractors. Because increasing attention to an object would enhance the early processing of this object, we thus hypothesized that augmenting the level of attention to a distractor might lead to a higher level of inhi-bition, revealed as a corresponding augmentation in the magnitude of NP effect. To test this assumption, an object- based identification task was then applied, and participants were asked to make the animate/inanimate categorization. Attention level was manipulated by varying the relative spa-tial locations of target and distractor (overlapped or sepa-rated). A reliable greater NP effect was found in the over-lapped than separated condition, indicating that distractors under the high-level attention condition (overlapped) got greater initial excitation, and then evoked greater subsequent inhibitory feedbacks, therefore resulting in a larger NP effect. These results provide direct evidence for the reactive inhibi-tion suggested by the Houghton and Tipper model. Mean-while a coincident greater positive priming (PP) effect was obtained under the overlapped than separated condition, which could be attributed to the higher level of target activa-tion in the overlapped condition. The covariation of NP and PP effects further confirmed that the way of our manipula-tion on attention level展开更多
Authors conducted pollination experiments and genetic analyses using microsatellite loci for a natural population of a shrub species,Magnolia salicifolia,in a secondary Japanese beech forest in Hakkoda mountains,north...Authors conducted pollination experiments and genetic analyses using microsatellite loci for a natural population of a shrub species,Magnolia salicifolia,in a secondary Japanese beech forest in Hakkoda mountains,northern Japan,to analyze inbreeding and inbreeding depression that involve sexual reproduction and population genetic structure of the species.The pollination experiments revealed that self-fertilization through geitonogamy is possible and that the magnitude of inbreeding depression(δ)at the embryonic stage is substantial(δ=0.42),suggesting that the inbreeding depression due to self-fertilization decreases seed production of the natural population.The genetic analyses showed discrepancy in the level of inbreeding between life history stages:the inbreeding coefficient for the juvenile and adult stage was 0.17 and 0.01,respectively,implying that most of inbred progenies cannot grow to the adult stage in the population,since the cumulative inbreeding depression is severe.These results are consistent with the hypothesis that explains mechanisms causing stable maintenance of severe inbreeding depression in partially inbred populations by focusing on the selective interference among deleterious mutations.It is suggested that some reproductive traits facilitating outcrossing in the species would be attributed to the severe cumulative inbreeding depression.展开更多
基金supported by a National Research Foundation of Korea(NRF)grant,funded by the Korean government(MSIT)(NRF-2020M3H4A1A02084898 and NRF-2019M3C7A1032076)the Technology Innovation Program(20013794,Center for Composite Materials and Concurrent Design)funded by the Ministry of Trade,Industry&Energy(MOTIE,Korea).
文摘The miniaturization and high integration of devices demand significant thermal management materials.Current technologies for the thermal management of electronics show some limitations in the case of multiple chip arrays.A device in multiple chip array is affected by heat from adjacent devices,along with thermal conductive composite.To address this problem,we present a nano composite of aligned boron nitride(BN)nanosheet islands with porous polydimethylsiloxane(PDMS)foam to have mechanical stability and non-thermal interference.The islands of tetrahedrally-structured BN in the composite have a high thermal conductivity of 1.219 W·m^(-1)·K^(-1) in the through-plane direction(11.234W·m^(-1)·K^(-1)in the in-plane direction)with 16 wt.%loading of BN.On the other hand,porous PDMS foam has a low thermal conductivity of 0.0328W·m^(-1)·K^(-1) in the through-plane direction at 70%porosity.Heat pathways are then formed only in the structured BN islands of the composite.The porous PDMS foam can be applied as a thermal barrier between structured BN islands to inhibit thermal interference in multiple device arrays.Furthermore,this composite can maintain selective thermal dissipation performance with 70%tensile strain.Another beauty of the work is that it could have guided heat dissipation by assembling of multiple layers which have high vertical thermal conductive islands,while inhibiting thermal interference.The selective heat dissipating composite can be applied as a heatsink for multiple chip arrays electronics.
基金Supported by the National Natural Science Foundation of China (No. 60573112)
文摘In doubly-selective fading wireless channel, the conventional orthogonal frequency division multi-plexing （OFDM） receivers for inter-cartier interference （ICI） compensation require extensive computations. To obtain an effective balance between performance and complexity, the whole channel response matrix was decomposed into a sequence of submatrix, and then a novel equalizer based on minimum mean square error （MMSE） criterion was presented to combat the ICI. Furthermore, a simple ordering-based decision-feedback equalizer （DFE） Was derived to exploit the temperal diversity gain offered by mobile channels. Numerical studies illustrate that although the MMSE equalizer still suffers from error floor, whereas the DICE equalizer exhibits significant performance improvement. The advantage of the proposed scheme indicates its potential applications in the future broadband wireless systems.
基金This work was supported by the National Natural Science Foundation of China (Grant Nos. 30100053 & 30470570).
文摘Selective attention has been viewed as a dual- process mechanism, that is, exciting targets and inhibiting distractors. Most early studies concentrated mainly on the target-excitation, whereas recent investigations began to pay more attention to the inhibitory selective attention mecha-nism. A measure named negative priming (NP) was exten-sively employed to probe into the inhibitory processes. The Houghton and Tipper Model put forward a notion: the inhi-bition that feeds back to the distractor is reactive. That means, the level of inhibition is determined by the activation state of the distractor. Distractors that are more salient and intrude into the control of action receive greater inhibitory feedbacks than less salient distractors. Because increasing attention to an object would enhance the early processing of this object, we thus hypothesized that augmenting the level of attention to a distractor might lead to a higher level of inhi-bition, revealed as a corresponding augmentation in the magnitude of NP effect. To test this assumption, an object- based identification task was then applied, and participants were asked to make the animate/inanimate categorization. Attention level was manipulated by varying the relative spa-tial locations of target and distractor (overlapped or sepa-rated). A reliable greater NP effect was found in the over-lapped than separated condition, indicating that distractors under the high-level attention condition (overlapped) got greater initial excitation, and then evoked greater subsequent inhibitory feedbacks, therefore resulting in a larger NP effect. These results provide direct evidence for the reactive inhibi-tion suggested by the Houghton and Tipper model. Mean-while a coincident greater positive priming (PP) effect was obtained under the overlapped than separated condition, which could be attributed to the higher level of target activa-tion in the overlapped condition. The covariation of NP and PP effects further confirmed that the way of our manipula-tion on attention level
基金supported by JSPS KAKENHI(Grant number 18380099).
文摘Authors conducted pollination experiments and genetic analyses using microsatellite loci for a natural population of a shrub species,Magnolia salicifolia,in a secondary Japanese beech forest in Hakkoda mountains,northern Japan,to analyze inbreeding and inbreeding depression that involve sexual reproduction and population genetic structure of the species.The pollination experiments revealed that self-fertilization through geitonogamy is possible and that the magnitude of inbreeding depression(δ)at the embryonic stage is substantial(δ=0.42),suggesting that the inbreeding depression due to self-fertilization decreases seed production of the natural population.The genetic analyses showed discrepancy in the level of inbreeding between life history stages:the inbreeding coefficient for the juvenile and adult stage was 0.17 and 0.01,respectively,implying that most of inbred progenies cannot grow to the adult stage in the population,since the cumulative inbreeding depression is severe.These results are consistent with the hypothesis that explains mechanisms causing stable maintenance of severe inbreeding depression in partially inbred populations by focusing on the selective interference among deleterious mutations.It is suggested that some reproductive traits facilitating outcrossing in the species would be attributed to the severe cumulative inbreeding depression.
