Statistical properties of solar energetic proton events

The Sun is the source of several different kinds of high-energy particles that are most prominently released in sudden large eruptions, known as solar energetic particle events. These particles, which escape the Sun and are accelerated in the coronal plasma, contribute substantially to the radiation environment in near-Earth and interplanetary space and therefore constitute an important consideration in mitigating the risks of space missions and other space-related human activities. Although the basic mechanisms related to energetic particle release and acceleration are fairly well known in principle, electrically charged particles are subjected to multiple complicated physical processes between their point of origin and an observer in interplanetary space. This fact, together with the changing conditions at the particle source, causes the observed particle event characteristics to vary a great deal, seriously complicating any attempt to understand, model, and predict their fluxes in near-Earth space. In the work forming the basis for this dissertation, we examined three large selections of solar energetic particle events through various statistical methods. Relying on data mainly collected by spacecraft, we identified particle events that fulfilled certain criteria, determined their likely association with other solar phenomena (such as solar flares and coronal mass ejections), and characterised the events by calculating estimates for their intensity rise times, the differences between the particle injection times derived using different methods, the magnetic connectivity between the particle source and the observer, and various other quantities. These observables were studied for statistically significant dependencies in order to uncover information about particle release and transport. The event listing compiled for the first of the three articles included herein was additionally made available as an electronic online catalogue that has been thereafter regularly updated by the author. We found that the features of solar energetic particle events do not exhibit any general, straightforward dependence on the longitudinal distance or the magnetic connectivity between the particle source and the observer, especially in their initial phase. The studied event populations appear highly variable in this respect, and they might include several different classes of events that are not readily distinguishable based on the available information. However, the intensity rise times, the delays between the event-related X-ray flare and the modelled event onset, as well as the relative durations of events, would seem to be at least somewhat dependent on the magnetic connectivity and the iron abundance of the event: a strong modelled magnetic connection and iron-rich composition tend to imply a proton event that rises more quickly and lasts for a shorter period of time than does an event with the opposite characteristics. The longitudinal spread of energetic particles in large events is not strongly dependent on particle energy, but might depend on the general solar cycle-specific conditions in interplanetary space. Overall, our results underscore the desirability of combining good observational statistics with reasonably comprehensive numerical modelling of particle transport effects in efforts to gain a better understanding of the processes involved in solar particle events and to develop applications for predicting these events

Catalogue of 55-80 MeV solar proton events extending through solar cycles 23 and 24

We present a new catalogue of solar energetic particle events near the Earth, covering solar cycle 23 and the majority of solar cycle 24 (1996-2016), based on the 55-80 MeV proton intensity data gathered by the SOHO/ERNE experiment. In addition to ERNE proton and heavy ion observations, data from the ACE/EPAM (near-relativistic electrons), SOHO/EPHIN (relativistic electrons), SOHO/LASCO (coronal mass ejections, CMEs), and GOES soft X-ray experiments are also considered and the associations between the particle and CME/X-ray events deduced to obtain a better understanding of each event. A total of 176 SEP events have been identified as having occurred during the time period of interest; their onset and solar release times have been estimated using both velocity dispersion analysis (VDA) and time-shifting analysis (TSA) for protons, as well as TSA for near-relativistic electrons. Additionally, a brief statistical analysis has been performed on the VDA and TSA results, as well as the X-rays and CMEs associated with the proton/electron events, both to test the viability of the VDA and to investigate possible differences between the two solar cycles. We find, in confirmation of a number of previous studies, that VDA results for protons that yield an apparent path length of 1 AU < s <~ 3 AU seem to be useful, but those outside this range are probably unreliable, as evidenced by the anticorrelation between apparent path length and release time estimated from the X-ray activity. It also appears that even the first-arriving energetic protons apparently undergo significant pitch angle scattering in the interplanetary medium, with the resulting apparent path length being on average about twice the length of the spiral magnetic field. The analysis indicates an increase in high-energy SEP events originating from the far eastern solar hemisphere; e.g., such an event...Comment: 33 pages, 12 figures (2 with multiple image files), 1 appendix as an external PDF file. Article is in the accepted manuscript/referee (single column) forma

Evaluation of asthma risk index application in treating early childhood asthma

Abstract Finnish current care guidelines recommend that the treatment of asthma in young children should be based on the number of wheezing episodes and on the assessment of asthma risk profile consisting of two major and three minor criteria, constructed on the basis of the international asthma predictive index. The aim of the present study was to assess whether the current guidelines and risk profile determination are applied in the treatment of asthma in children aged less than three years. In all, 179 children aged 1-35 months were admitted for wheezing during four winter-months from 1 st Nov, 2006 to 28 th Feb. 2007. The data on treatment decisions, and major and minor asthma risk factors were retrospectively collected from patient records. Recorded data sufficient for the retrospective determination of the asthma risk profile were found for 112/179(63 %) children. Data on minor criteria were missing in almost all cases. Most of the children with data not available were first-time wheezers. Twenty-one children (19%) were on maintenance medication at admission. The decision whether or not to start maintenance medication was in line with the current care guidelines in 76/91(84 %) children. In conclusion, the treatment of asthma in young children mostly took place according to the national current care guidelines, though the application of the asthma risk profile was insufficient. The minor criteria of the asthma risk profile are not sufficiently sensible for clinical practice, and therefore need to be up-to-dated

Outcome of oral immunotherapy for persistent cow's milk allergy from 11 years of experience in Finland

Background: The safety and efficacy of long-term milk oral immunotherapy (OIT) in Finnish children with persistent cow's milk allergy (CMA) were evaluated in an open-label, non-randomized study. Methods: During the 11-year study, 296 children aged 5 years or older with immunoglobulin E (IgE)-mediated CMA started milk OIT. Follow-up data were collected at three time points: the post-buildup phase, 1 year thereafter, and at the cross-sectional long-term follow-up between January 2016 and December 2017. Patients were divided according to baseline milk-specific IgE (sIgE) level and by the amount of milk consumption at the long-term follow-up. The high-dose group consumed >= 2 dL of milk daily, while the failure group consumed Results: Out of the initial study group, 244/296 (83%) patients participated in the long-term follow-up. Among these patients, 136/244 (56%) consumed >= 2 dL of milk daily. The median follow-up time was 6.5 years. Of the recorded markers and clinical factors, the baseline milk sIgE level was most associated with maintaining milk OIT (P <0.001). Respiratory symptoms in the post-buildup phase increased the risk of treatment failure (OR 3.5, 95% CI: 1.5-8.1, P = 0.003) and anaphylaxis (OR 14.3, 95% CI: 1.8-114, P = 0.01). Conclusion: More than half of the patients were able to maintain the targeted milk dose in their daily diet. Baseline milk sIgE level and reactivity during the early treatment stage strongly predicted the long-term outcome and safety of milk OIT.Peer reviewe

Cardiorespiratory Coupling in Asthmatic Children

The relationship between cardiac and respiratory autonomic control has been suggested to be altered in several respiratory disorders. However, and despite the increasing prevalence of asthma, there are not studies assessing the cardiorespiratory coupling (CRC) with respect to the asthmatic status. Since altered autonomic control has been suggested to play a major role in asthma, in this work overnight CRC was assessed in a group of 67 children who underwent a three-month inhaled corticosteroids treatment. After treatment completion, CRC was reduced (p < 0.005) in the subjects without or with a low risk of asthma, whereas it kept unchanged in those with a worse prognosis, suggesting that an altered interaction between cardiac and respiratory activity might be related with an increased risk of asthma

Noninvasive cardiorespiratory signals analysis for asthma evolution monitoring in preschool children

Despite its increasing prevalence, diagnosis of asthma in children remains problematic due to their difficulties in producing repeatable spirometric maneuvers. Moreover, low adherence to inhaled corticosteroids (ICS) treatment could result in permanent airway remodeling. The growing interest in a noninvasive and objective way for monitoring asthma, together with the apparent role of autonomic nervous system (ANS) in its pathogenesis, have attracted interest towards heart rate variability (HRV) and cardiorespiratory coupling (CRC) analyses. In this work, HRV and CRC were analyzed in 70 children who were prescribed ICS treatment due to obstructive bronchitis. They underwent three different electrocardiogram and respiratory signals recordings, during and after treatment period. After treatment completion, they were followed up during 6 months and classified attending to their current asthma status. Vagal activity, as measured from HRV, and CRC, were reduced after treatment in those children at lower risk of asthma, whereas it kept unchanged in those with a worse prognosis. Results suggest that HRV analysis could be useful for the continuous monitoring of ANS anomalies present in asthma, thus contributing to evaluate the evolution of the disease, which is especially challenging in young children

Noninvasive Cardiorespiratory Signals Analysis for Asthma Evolution Monitoring in Preschool Children

OBJECTIVE: Despite its increasing prevalence, diagnosis of asthma in children remains problematic due to their difficulties in producing repeatable spirometric maneuvers. Moreover, low adherence to inhaled corticosteroids (ICS) treatment could result in permanent airway remodeling. The growing interest in a noninvasive and objective way for monitoring asthma, together with the apparent role of autonomic nervous system (ANS) in its pathogenesis, have attracted interest towards heart rate variability (HRV) and cardiorespiratory coupling (CRC) analyses. METHODS: HRV and CRC were analyzed in 70 children who were prescribed ICS treatment due to recurrent obstructive bronchitis. They underwent three different electrocardiogram and respiratory signals recordings, during and after treatment period. After treatment completion, they were followed up during 6 months and classified attending to their current asthma status. RESULTS: Vagal activity, as measured from HRV, and CRC, were reduced after treatment in those children at lower risk of asthma, whereas it kept unchanged in those with a worse prognosis. CONCLUSION: Results suggest that HRV analysis could be useful for the continuous monitoring of ANS anomalies present in asthma, thus contributing to evaluate the evolution of the disease, which is especially challenging in young children. SIGNIFICANCE: Noninvasive ANS assessment using HRV analysis could be useful in the continuous monitoring of asthma in children