Covariation judgment underlies a diversity of psychological theories and influences various everyday decisions.Information about covariation can be learned from either a summary description of frequencies(i.e.,conting...Covariation judgment underlies a diversity of psychological theories and influences various everyday decisions.Information about covariation can be learned from either a summary description of frequencies(i.e.,contingency tables)or trial-by-trial experience(i.e.,sampling individual instances).Two studies were conducted to investigate the impact of information learning mode(i.e.,description vs.self-truncated sampling)on covariation judgment and related decision.In each trial under the description condition,participants were presented with a contingency table with explicit cell frequencies,whereas in each trial under the self-truncated sampling condition,participants were allowed to determine when to stop sampling instances and thus the actual sample size.To eliminate sampling error,an other-yoked(i.e.,between-subject)design was used in this research so that cell frequencies shown in a trial under the description condition were matched with those experienced in a trial under the self-truncated sampling condition.Experiment 1 showed that the selftruncated sampling condition led to more moderate covariation judgments than the description condition(i.e.,a description-experience gap).Experiment 2 demonstrated further that the same gap extended to covariation-related decisions in terms of relative contingent preference(RCP).Regressive frequency estimation under self-truncated sampling appeared to underlie the consistent gaps found in the two studies,whereas the impact of regressive diagnosticity(i.e.,the same sample of instances was viewed as less diagnostic under description than under self-truncated sampling)or simultaneous overestimation and underweighting of rare instances under experience was not supported by the observed data.Future research might examine alternative accounts of the observed gaps,such as the impacts of belief updating and stopping rule under self-truncated sampling.展开更多
Ionization-induced electron injection in laser wakefield accelerators, which was recently proposed to lower the laser intensity threshold for electron trapping into the wake wave, has the drawback of generating electr...Ionization-induced electron injection in laser wakefield accelerators, which was recently proposed to lower the laser intensity threshold for electron trapping into the wake wave, has the drawback of generating electron beams with large and continuous energy spreads, severely limiting their future applications. Complex target designs based on separating the electron trapping and acceleration stages were proposed as the only way for getting small energy-spread electron beams. Here, based on the self-truncated ionization-injection concept which requires the use of unmatched laser–plasma parameters and by using tens of TW laser pulses focused onto a gas jet of helium mixed with low concentrations of nitrogen, we demonstrate single-stage laser wakefield acceleration of multi-hundred MeV electron bunches with energy spreads of a few percent. The experimental results are verified by PIC simulations.展开更多
基金National Natural Science Foundation of China,Grant/Award Number:31872780。
文摘Covariation judgment underlies a diversity of psychological theories and influences various everyday decisions.Information about covariation can be learned from either a summary description of frequencies(i.e.,contingency tables)or trial-by-trial experience(i.e.,sampling individual instances).Two studies were conducted to investigate the impact of information learning mode(i.e.,description vs.self-truncated sampling)on covariation judgment and related decision.In each trial under the description condition,participants were presented with a contingency table with explicit cell frequencies,whereas in each trial under the self-truncated sampling condition,participants were allowed to determine when to stop sampling instances and thus the actual sample size.To eliminate sampling error,an other-yoked(i.e.,between-subject)design was used in this research so that cell frequencies shown in a trial under the description condition were matched with those experienced in a trial under the self-truncated sampling condition.Experiment 1 showed that the selftruncated sampling condition led to more moderate covariation judgments than the description condition(i.e.,a description-experience gap).Experiment 2 demonstrated further that the same gap extended to covariation-related decisions in terms of relative contingent preference(RCP).Regressive frequency estimation under self-truncated sampling appeared to underlie the consistent gaps found in the two studies,whereas the impact of regressive diagnosticity(i.e.,the same sample of instances was viewed as less diagnostic under description than under self-truncated sampling)or simultaneous overestimation and underweighting of rare instances under experience was not supported by the observed data.Future research might examine alternative accounts of the observed gaps,such as the impacts of belief updating and stopping rule under self-truncated sampling.
基金supported by the National ‘973’ Program of China under Grant No.2013CBA01504supported by Shanghai Supercomputer Center and the center for high performance computing at Shanghai Jiao Tong University
文摘Ionization-induced electron injection in laser wakefield accelerators, which was recently proposed to lower the laser intensity threshold for electron trapping into the wake wave, has the drawback of generating electron beams with large and continuous energy spreads, severely limiting their future applications. Complex target designs based on separating the electron trapping and acceleration stages were proposed as the only way for getting small energy-spread electron beams. Here, based on the self-truncated ionization-injection concept which requires the use of unmatched laser–plasma parameters and by using tens of TW laser pulses focused onto a gas jet of helium mixed with low concentrations of nitrogen, we demonstrate single-stage laser wakefield acceleration of multi-hundred MeV electron bunches with energy spreads of a few percent. The experimental results are verified by PIC simulations.
