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To explore the influence of the lightning detection station layout on lightning location accuracy, the magnetic field waveform observation data from the natural lightning observation test base at Jiuxian Mountain in Fujian Province were used and ten return strokes of cloud-to-ground flashes from different orientations and distances both inside and outside of the detection network were selected. Using the time of arrival (TOA) method and the positioning results by 10 (or 9) stations as the references, we compared and analyzed the discrepancies of location results under different combinations of 5 to 8 stations. The possible reasons for the discrepancies in the location results were also explored. The results show that lightning location is closely related to the number of stations and the layout of the stations. For the same number of stations, large differences in the location results can be found for different station layouts, but with the increase in the number of stations, the differences caused by different station layouts gradually decrease. For the location with the same number and layout of stations, there are also significant differences in the localization deviations for lightning from different orientations and distances. The deviation of lightning localization outside of the network is significantly larger than that inside the network. The positions of lightning outside the network often show a "band-like distribution", and the farther the lightning is away from the network, the more obvious the deviation of this "band-like distribution" is. This is due to the narrow spatial region formed by the intersection of hyperbolas.

Abstract Background A few previous cross-sectional studies investigated correlated factors of suicidal ideation or suicide attempts among suicide prevention hotline callers; however, scarcely any evidence was from a longitudinal study. In addition, it is still unclear whether improvements in some suicide risk factors could reduce the occurrence of subsequent suicidal acts. This longitudinal study focusing on the risk factors for subsequent suicidal acts among adolescent and young adult callers with high suicide risk aims to fill this gap. Methods This study recruited 12–25-year-old high-risk callers to a China nationwide suicide prevention hotline. Potential risk factors, including hopefulness, psychological distress, depression, history of suicide attempts, alcohol or substance misuse, and acute life events, were examined during the index calls, and improvements in hopefulness, psychological distress, and suicide intent were assessed before ending the index calls. The recruited callers were followed up 12 months after their index calls. The primary outcome was the occurrence of suicidal acts (suicide attempts or suicide death) during follow-up. Kaplan–Meier survival curves, log-rank tests, and Cox proportional hazards model were used. Results During the follow-up period, 271 of 1656 high-risk adolescent and young adult callers attempted suicide, and seven callers died by suicide. After adjusting for demographic variables, low hopefulness (Hazard Ratio [HR] = 2.03, 95% Confidence Interval [CI]=[1.47, 2.80]) at the beginning of the index call was associated with a higher risk for subsequent suicidal acts, whereas improvements in psychological distress (HR = 0.61, 95%CI [0.41, 0.89]) and suicidal intent (HR = 0.56, 95%CI [0.38, 0.84]) during the index call reduced the risk of subsequent suicidal acts. In addition, alcohol or substance misuse (Model 2, HR = 1.65, 95%CI [1.11, 2.46]) and suicide attempt history(Model 1: one episode, HR = 1.96, 95%CI=[1.05, 3.66]; two or more episodes, HR = 2.81, 95%CI [1.59, 4.96]. Model 2: one episode, HR = 2.26, 95%CI [1.06, 4.82]; two or more episodes: HR = 3.28, 95%CI [1.63, 6.60]) were risk factors for subsequent suicidal acts. Conclusions While suicide prevention hotline operators deliver brief psychological interventions to high-risk adolescent and young adult callers, priority should be given to callers with low hopefulness and to the alleviation of callers’ high psychological distress and suicide intent.

Relationships between terrorists are amorphous, invisible, distributed, and dispersed. The information on these networks is often incomplete and even erroneous. The key to disrupting the terrorists' network is to find the critical nodes whose removal will lead to network collapse, and however, most of the previous studies are based directly on the observed networks while neglecting an important fact that the observed networks may be incomplete. In this paper, we address the terrorist network disintegration problem based on link prediction. An effective method is proposed to find the critical nodes by the assistance of a link prediction algorithm. We make a case study of September 11th hijackers to illustrate our method. Five different disintegration strategies are applied to validate our method. The result shows that, with no more than 40% magnitude of missing information, by using the link prediction method to recover partial missing relationships information, our method can improve the network disintegration performance remarkably. Besides, we find that when the size of missing information is not too much, our method even outperforms than the results based on complete information. We refer to this phenomenon as the “comic effect” of link prediction, which means that the original network has been reshaped through the addition of some links by link prediction. As a result, the reshaped network is like an exaggerated but characteristic comic of the original one, where the important parts are emphasized.