分类： 天文学 >> 天文学 提交时间： 2023-02-19
摘要： The separation of a filament and sigmoid is observed during an X1.4 flare on July 12, 2012 in solar active region 11520, but the corresponding magnetic field change is not clear. We construct a data-constrained magnetohydrodynamic simulation of the filament-sigmoid system with the flux rope insertion method and magnetic flux eruption code, which produces the magnetic field evolution that may explain the separation of the low-lying filament and high-lying hot channel (sigmoid). The initial state of the magnetic model contains a magnetic flux rope with a hyperbolic flux tube, a null point structure and overlying confining magnetic fields. We find that the magnetic reconnections at the null point make the right footpoint of the sigmoid move from one positive magnetic polarity (P1) to another (P3). The tether-cutting reconnection at the hyperbolic flux tube occurs and quickly cuts off the connection of the low-lying filament and high-lying sigmoid. In the end, the high-lying sigmoid erupts and grows into a coronal mass ejection, while the low-lying filament stays stable. The observed double J-shaped flare ribbons, semi-circular ribbon, and brightenings of several loops are reproduced in the simulation, where the eruption of the magnetic flux rope includes the impulsive acceleration and propagation phases.
分类： 天文学 >> 天文学 提交时间： 2023-02-19
摘要： We present the analysis of three kinds of oscillating behavior using multi-wavelength observations of the 10 November 2013 (SOL2013-11-10T05:14) circular-ribbon flare. This event is a typical circular-ribbon flare with an outer spine structure and homologous jets. We found three kinds of oscillations (or perturbations): i) flux oscillation (or QPP) with a dominant period of about 20 seconds in X-ray, EUV, and microwave emissions, ii) periodic jets with an intermittent cadence of around 72 seconds, iii) an outer loop perturbing half a cycle with a duration of about 168 seconds. Similar to the periodic jets that could be produced by a nonthermal process, like repeated magnetic reconnection, the flare QPP detected in the thermal emissions could have the same origin as the oscillation seen in the nonthermal emissions. The outer-loop perturbation is possibly triggered by a blast wave driven by the circular-ribbon flare, or it might be modulated by the sausage wave or the slow magnetoacoustic wave. The results obtained provide data for further numerical studies on the physical origin of the flare oscillations.
分类： 天文学 >> 天文学 提交时间： 2023-02-19
摘要： We present an investigation of partial filament eruption on 2012 June 17 in the active region NOAA 11504. For the first time, we observed the vertical splitting process during the partial eruption with high resolution narrow band images at 10830 . The active filament was rooted in a small sunspot of the active region. Particularly, it underwent the partial eruption in three steps, i.e. the precursor, the first eruption, and the second eruption, while the later two were associated with a C1.0 flare and a C3.9 flare, respectively. During the precursor, slow magnetic reconnection took place between the filament and the adjoining loops that also rooted in the sunspot. The continuous reconnection not only caused the filament to split into three groups of threads vertically but also formed a new filament, which was growing and accompanied brightening took place around the site. Subsequently, the growing filament erupted together with one group splitted threads, resulted in the first eruption. At the beginning of the first eruption, a subsequent magnetic reconnection occurred between the erupting splitted threads and another ambient magnetic loop. After about three minutes, the second eruption occurred as a result of the eruption of two larger unstable filaments induced by the magnetic reconnection. The high-resolution observation provides a direct evidence that magnetic reconnection between filament and its ambient magnetic fields could induce the vertical splitting of the filament, resulting in partial eruption.
分类： 天文学 >> 天文学 提交时间： 2023-02-19
摘要： With high-resolution narrowband He I 10830 \r{A} filtergrams from GST, we give an extensive analysis for 4 granular sized microeruptions which appear as the gentle ejection of material in He I 10830 \r{A} band. The analysis was aided with the EUV data from AIA and line-of-sight magnetograms from HMI on board SDO. The microeruptions are situated on magnetic polarity inversion lines (PILs), and their roots are accurately traced down to intergranular lanes. Their durations are different, two microeruptions are repetitive microjets, lasting ~ 50 and 27 minutes respectively, while the other two events are singular, lasting ~ 5 minutes. For the two microjets, they are continuous and recurrent in He I 10830 \r{A} band, and the recurrence is quasi-periodic with the period of ~ 5 minutes. We found that only transient co-spatial EUV brightenings are observed for the longer duration microjets and EUV brightenings are absent for the two singular microeruptions. What is essential to the longer duration microjets is that granules with the concentration of positive magnetic field persistently transport the magnetic field to the PILs, canceling the opposite magnetic flux and making the base of the two microjets and the underlying granules migrate with the speed of ~ 0.25 and 1.0 km/s. The observations support the scenario of magnetic reconnection for the quasi-periodic microjets and further show that the reconnection continuously generates multi-temperature components, especially the cool component with chromospheric temperature. In addition, the ongoing reconnection is modulated by p-mode oscillations inside the Sun.
分类： 天文学 >> 天文学 提交时间： 2023-02-19
摘要： The separation of a filament and sigmoid is observed during an X1.4 flare on July 12, 2012 in solar active region 11520, but the corresponding magnetic field change is not clear. We construct a data-constrained magnetohydrodynamic simulation of the filament-sigmoid system with the flux rope insertion method and magnetic flux eruption code, which produces the magnetic field evolution that may explain the separation of the low-lying filament and high-lying hot channel (sigmoid). The initial state of the magnetic model contains a magnetic flux rope with a hyperbolic flux tube, a null point structure and overlying confining magnetic fields. We find that the magnetic reconnections at the null point make the right footpoint of the sigmoid move from one positive magnetic polarity (P1) to another (P3). The tether-cutting reconnection at the hyperbolic flux tube occurs and quickly cuts off the connection of the low-lying filament and high-lying sigmoid. In the end, the high-lying sigmoid erupts and grows into a coronal mass ejection, while the low-lying filament stays stable. The observed double J-shaped flare ribbons, semi-circular ribbon, and brightenings of several loops are reproduced in the simulation, where the eruption of the magnetic flux rope includes the impulsive acceleration and propagation phases.
分类： 光学 >> 量子光学 提交时间： 2023-02-19
Mengqi Wang
Haoyu Sun
Xiangyu Ye
Pei Yu
Hangyu Liu
Jingwei Zhou
Pengfei Wang
Fazhan Shi
Ya Wang
Jiangfeng Du
摘要： To efficiently align the creation of defect center with photonics structure in nanoscale precision is one of the outstanding challenges for realizing high-performance photonic devices and the application in quantum technology such as quantum sensing, scalable quantum systems, and quantum computing network. Here, we propose a facile self-aligned patterning technique wholly based on conventional engineering technology, with the doping precision can reach ~15nm. Specifically, we demonstrate this technique by fabricating diamond nanopillar sensor arrays, which show high consistency and near-optimal photon counts, high yield approaching the theoretical limit, and high filtering efficiency for different NV centers. Combined with appropriate crystal orientation, a saturated fluorescence rate of 4.65 Mcps and the best reported fluorescence-dependent detection sensitivity of 1900 cps^(-1/2) are achieved. This technique applicable to all similar solid-state systems should facilitate the development of parallel quantum sensing and scalable information processing.
分类： 心理学 >> 认知心理学 提交时间： 2020-07-27
摘要： Delay discounting (DD) is the phenomenon that individuals prefer to choose an immediate but smaller reward than a delayed but larger reward. Larger DD is considered as an indicator of impulsivity, the increased DD rate is also seen as a behavior indictor of various psychiatric disorders. Episodic future thinking (EFT) is the ability to project oneself into the future to pre-experience the future events, which can be used to reduce DD. The present study provided a meta-analysis on the efficiency of EFT in reducing DD and examined potential moderators. Thirty-seven studies including 48 contrasts were included, results showed that EFT reduced DD significantly. Moderator and meta-regression analyses revealed that positive EFT was more efficient in reducing DD. In addition, several factors related to DD task (e.g., whether the DD money is hypothetical or potential real, whether the delay reward is fixed or variable, and the indexes of DD) were related to the efficiency of EFT in reducing DD. These results have implications for using EFT to reduce DD in the future.
分类： 心理学 >> 医学心理学 提交时间： 2019-11-05
摘要： Individuals with autism spectrum disorders (ASD) have a wide range of cognitive impairments. Mental time travel (MTT) is the ability to mentally re-experience past events and pre-experience possible future events. Studies have shown MTT impairments in individuals with ASD, however, these findings may be confounded by a number of factors including verbal ability to report MTT, factors related to MTT task and demographic factors of participants. The present study provided a meta-analysis on MTT deficits in individuals with ASD and examined the potential moderating variables for these impairments. Twenty-six studies were included, and the participants comprised 667 individuals with ASD and 671 healthy controls. Results showed significant overall MTT impairments (Cohen’s d = −0.95) in individuals with ASD. Moderator and meta-regression analyses revealed that verbal IQ was significantly related to MTT impairments; type of MTT, type of task, measurement indices of MTT, age of participants, gender ratio and full IQ did not explain the MTT impairments. These findings suggest that MTT is severely impaired in individuals with ASD, verbal IQ contributed to MTT impairments, and task characteristics did not affect the degree of impairments.
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