High-Resolution Measurements of e+ + H2O Total Cross Section

Using a purely positron beam, the total cross section of positrons scattering from H2O has been measured for the first time with a high angular discrimination (≃1°) against forward scattered projectiles. Results are presented in the energy range (10-300) eV. Significant deviations from previous measurements are found which are, if ascribed entirely to the angular acceptances of various experimental systems, in quantitative accord with ab initio theoretical predictions of the differential elastic scattering cross section

Occurrence Distribution of Polar Cap Patches: Dependences on UT, Season and Hemisphere

Polar cap patches are islands of enhanced electron density in the polar cap F region ionosphere, which sometimes affect the propagation of trans-ionospheric radio waves. Considering the intake of daytime sunlit plasma by the high-latitude convection as the primary cause of patches, the spatial overlap between the convection and the daytime sunlit plasma should be one of the critical factors controlling the generation of patches. To confirm this hypothesis, we statistically investigated the UT and seasonal distributions of patch occurrence frequency in both the hemispheres by using in situ plasma density data from the Swarm satellite. As a result, it was found that the occurrence distribution of patches is a complex function of UT, season and hemisphere, but it can be mostly interpreted by the spatial overlap between the high-latitude convection and the solar terminator. This suggests that polar cap patches are not necessarily phenomena that occur only during winter months. That is, patches can often be observed even in periods away from the winter solstice if the location of solar terminator in the magnetic coordinate system is appropriate for the generation of patches. For example, in the southern hemisphere, where the offset between the geographic and magnetic poles is larger than that in the northern hemisphere, the highest patch occurrence rate is obtained around the equinoctial periods. These results indicate that it is needed to take these dependences into account when we discuss and predict the space weather impacts of patches on the trans-ionospheric radio propagation

Pi pulsation signatures at substorm onset: An analysis of the 30 September 2011 substorm event using induction magnetometer records and all-sky images obtained at the conjugate stations, Syowa in Antarctica and Husafell, Tjornes in Iceland

第3回極域科学シンポジウム/第36回極域宙空圏シンポジウム 11月27日（火） 国立極地研究所 2階大会議

Simultaneous ground-based and satellite observations of natural VLF waves in Antarctica: A case study of downward ionospheric penetration of whistler-mode waves

AbstractTo investigate downward ionospheric-penetration characteristics of VLF (several hundred Hz to 17.8 kHz) whistler-mode waves, we conducted simultaneous observations (in 2006) of natural VLF waves using both ground stations in Antarctica and the Japanese Akebono satellite. The ground-based and satellite observations included an interesting event for which both observed similar VLF waves. In this study, we theoretically calculate down-going whistler-mode wave propagation based on ground-satellite observations using the full-wave analysis. In a case study, the observed wave-normal angles were approximately 140–160 degrees for a dayside chorus event on 15 March 2006. The theoretical calculation showed that the wave-normal angles for ionospheric penetration should be around 155.6 degrees, with its angular width of approximately 2 degrees. Moreover, the wave-energy loss due to ionospheric penetration is estimated at 20.4 dB based on our theoretical calculation, in accordance with the observed 17–19 dB

Application of generalized aurora computed tomography to the EISCAT_3D project

EISCAT_3D is a project to build a multi-site phased-array incoherent scatter radar system in northern Fenno-Scandinavia. We demonstrate via numerical simulation how useful monochromatic images taken by a multi-point imager network are for auroral research in the EISCAT_3D project. We apply the generalized aurora computed tomography (G-ACT) method to modelled observational data from real instruments, such as the Auroral Large Imaging System (ALIS) and the EISCAT_3D radar. G-ACT is a method for reconstructing the three-dimensional (3D) distribution of auroral emissions and ionospheric electron density (corresponding to the horizontal two-dimensional (2D) distribution of energy spectra of precipitating electrons) from multi-instrument data. It is assumed that the EISCAT_3D radar scans an area of 0.8° in geographic latitude and 3° in longitude at an altitude of 130 km with 10 × 10 beams from the radar core site at Skibotn (69.35° N, 20.37° E). Two neighboring discrete arcs are assumed to appear in the observation region of the EISCAT_3D radar. The reconstruction results from G-ACT are compared with those from the normal ACT as well as the ionospheric electron density from the radar. It is found that G-ACT can interpolate the ionospheric electron density at a much higher spatial resolution than that observed by the EISCAT_3D radar. Furthermore, the multiple arcs reconstructed by G-ACT are more precise than those by ACT. In particular, underestimation of the ionospheric electron density and precipitating electrons' energy fluxes inside the arcs is significantly improved by G-ACT including the EISCAT_3D data. Even when the ACT reconstruction is difficult due to the unsuitable locations of the imager sites relative to the discrete arcs and/or a small number of available images, G-ACT allows us to obtain better reconstruction results.</p

Pi pulsations at substorm onset site

第3回極域科学シンポジウム/第36回極域宙空圏シンポジウム 11月27日（火） 国立極地研究所 2階大会議

Study on spatiotemporal variations of ionospheric trough in auroral/subauroral region

第3回極域科学シンポジウム/第36回極域宙空圏シンポジウム 11月26日（月）、27日（火） 国立極地研究所 2階ラウン

Factors influencing completion of multi-dose vaccine schedules in adolescents: a systematic review

Background: Completion of multiple dose vaccine schedules is crucial to ensure a protective immune response, and maximise vaccine cost-effectiveness. While barriers and facilitators to vaccine uptake have recently been reviewed, there is no comprehensive review of factors influencing subsequent adherence or completion, which is key to achieving vaccine effectiveness. This study identifies and summarises the literature on factors affecting completion of multi-dose vaccine schedules by adolescents. Methods: Ten online databases and four websites were searched (February 2014). Studies with analysis of factors predicting completion of multi-dose vaccines were included. Study participants within 9-19 years of age were included in the review. The defined outcome was completion of the vaccine series within 1 year among those who received the first dose. Results: Overall, 6159 abstracts were screened, and 502 full texts were reviewed. Sixty one studies were eligible for this review. All except two were set in high-income countries. Included studies evaluated human papillomavirus vaccine, hepatitis A, hepatitis B, and varicella vaccines. Reported vaccine completion rates, among those who initiated vaccination, ranged from 27 % to over 90 %. Minority racial or ethnic groups and inadequate health insurance coverage were risk factors for low completion, irrespective of initiation rates. Parental healthcare seeking behaviour was positively associated with completion. Vaccine delivery in schools was associated with higher completion than delivery in the community or health facilities. Gender, prior healthcare use and socio-economic status rarely remained significant risks or protective factors in multivariate analysis. Conclusions: Almost all studies investigating factors affecting completion have been carried out in developed countries and investigate a limited range of variables. Increased understanding of barriers to completion in adolescents will be invaluable to future new vaccine introductions and the further development of an adolescent health platform

All-sky imager observations at South Pole Station: Recent advances and future challenges

第3回極域科学シンポジウム/第36回極域宙空圏シンポジウム 11月26日（月）、27日（火） 国立極地研究所 2階ラウン