Introducing the Novatron, a novel reactor concept

A new magnetic mirror design is described - the Novatron - with the potential to confine fully stable compact mirror-cusp fusion plasmas. The novel design features an axisymmetric magnetic field configuration with concave curvature throughout, as seen from the outside. Moreover, the Novatron is designed to be self-stabilized against the drift cyclotron loss-cone modes (DCLC). This paper describes the fundamental topology of the magnetic field and presents an outline for the design of the magnet system

Sensitivity study of seismic hazard prediction in Finland (SENSEI)

Abstract This report is a summary of earthquake hazard sensitivity assessments for Finnish nuclear power plant sites. In this research project, the impact of the input data parameters and modelling method choices of probabilistic earthquake risk assessments on the earthquake risk of Finnish nuclear power plant sites were studied. The latest hazard assessments of the three current and planned nuclear plant sites in Finland were used as reference data. The purpose was not to re-assess old estimates, but to find out which reasons have caused uncertainty and variation between hazard estimates. There were three parties in the project: The national radiation authority of Finland (STUK), a domestic calculation group responsible for making calculation models and calculations, and a foreign independent expert group. The calculation group had experience in making the previous risk assessments for the licensees and the expert group had experience with the latest calculation methods and an independent perspective on the previous assessments. The calculation team made comparative calculations using new software and attenuation functions also known as ground motion prediction equations (GMPEs). As a rule, the previously used seismic source area zonations were used, but special interest was focused on the seismicity of the rapakivi area near Loviisa. The earthquake catalogue used, was the seismological catalogue maintained by the University of Helsinki. In probabilistic earthquake risk assessments, the Gutenberg-Richter parameters describing seismicity and the applicable GMPE and its fitting to earthquake observations were identified as the most significant parameters causing uncertainties. The reason for this is the absence of strong and even medium-sized earthquakes in Finland, which leads to the parameters being fitted to the very few observations or the use of experience gained elsewhere, which is not necessarily suitable for Finland's hard bedrock conditions. Smaller uncertainties are caused by the maximum and minimum earthquake magnitude values used in the hazard assessment. Topics that can be excluded from assessments in Finland are, for example, soil liquefaction, soil modelling and local soil-induced vibration amplification, since so far, all nuclear facilities are built on bedrock. This assumption may change if small modular reactors (SMR) are built in new plant locations and new foundation conditions. Some expert recommendations for further research in Finland are the creation of a national hazard map to help in the siting of new facilities and the use of the GMPE NGA-East and/or the development of the national GMPE to better reflect local earthquake observations.Tiivistelmä Tämä raportti on yhteenveto maanjäristyshasardiarvion herkkyystarkasteluista suomalaisille ydinvoimalaitospaikoille. Tutkimusprojektissa selvitettiin todennäköisyyspohjaisten maanjäristyshasardiarvioiden lähtötietoparametrien ja mallinnustapavalintojen vaikutusta suomalaisten ydinvoimalaitospaikkojen maanjäristyshasardiin. Lähtötietoina käytettiin kolmen suomalaisen nykyisen ja suunnitellun ydinlaitospaikan viimeisimpiä hasardiarvioita. Tarkoituksena ei ollut arvioida vanhoja arviota vaan selvittää, mitkä syyt ovat aiheuttaneet epävarmuuksia ja vaihtelua hasardiarvioiden välille. Projektissa oli kolme osapuolta: STUK, kotimainen laskentaryhmä mallien ja hasardilaskentojen tekemistä varten ja ulkomainen itsenäinen asiantuntijaryhmä. Laskentaryhmällä oli kokemusta aikaisempien hasardiarvioiden tekemisestä ja asiantuntijaryhmällä oli kokemusta uusimmista laskentamenetelmistä ja aikaisemmista arvioista täysin riippumaton näkökulma. Laskentaryhmä teki vertailevat laskennat käyttäen uusia ohjelmistoja ja vaimennusfunktioita (GMPE). Seismiset lähdealuejaot olivat pääsääntöisesti samoja kuin aikaisemmissa hasardiarvioissa, mutta Loviisan rapakivialueen seismisyyteen kohdistettiin erityistä mielenkiintoa. Käytetty maajäristysluettelo eli seismologinen katalogi on Helsingin yliopiston ylläpitämä. Todennäköisyyspohjaisissa maanjäristyshasardiarvioissa merkittävimmiksi epävarmuuksia aiheuttaviksi parametreiksi tunnistettiin seismisyyttä kuvaavat Gutenberg-Richter parametrit ja käytettävä GMPE ja sen sovittaminen maanjäristyshavaintoihin. Syynä tähän on voimakkaiden ja jopa keskisuurten maanjäristysten puuttuminen Suomesta, joten parametrit on sovitettava vähäisten havaintojen perustella tai käytettävä muualta saatua kokemusta, joka ei välttämättä sovellu sellaisinaan Suomen kovaan kallioperään. Pienempiä epävarmuuksia aiheuttavat hasardiarviossa käytettävät maanjäristysmagnitudien maksimi ja minimi raja-arvot. Suomessa arvioista poisrajattavia asioita ovat mm. maaperän nesteytyminen, maaperän mallintaminen ja paikallinen maaperän aiheuttama värähtelyn voimistuminen, koska toistaiseksi kaikki ydinlaitokset on rakennettu peruskalliolle. Tämä tilanne voi muuttua, jos pieniä modulaarisia (SMR) laitoksia rakennetaan uusille laitospaikoille ja uusiin geologisiin olosuhteisiin. Asiantuntijaryhmän suosituksia jatkotutkimuksille Suomessa ovat kansallisen hasardikartan tekeminen uusien laitosten sijoittamisen avuksi sekä NGA-East GMPE:n käyttäminen ja/tai kansallisen GMPE:n kehittäminen vastaamaan paremmin paikallisia maanjäristyshavaintoja.Sammanfattning Denna rapport sammanfattar känslighetsstudier av seismiska hasardanalyser för finska kärnkraftverk. Forskningsprojektet undersökte effekten av indataparametrarna från probabilistiska jordbävningshasarduppskattningar och valet av modelleringsmetoder på jordbävningsrisken på finska kärnkraftsanläggningsplatser. De senaste hasard-uppskattningarna av de tre nuvarande och planerade kärnkraftsanläggningsplatserna i Finland användes som referenser. Syftet var inte att utvärdera tidigare uppskattningar, utan att ta reda på vilka bedömningar som orsakat osäkerheter och variationer mellan hasarduppskattningar. Projektet hade tre parter: STUK, en inhemsk beräkningsgrupp för modelleringen och hasardberäkningar och en utländsk oberoende expertgrupp. Beräkningsgruppen hade deltagit i de tidigare seismiska hasardanalyserna medan expertgruppen hade erfarenhet av de senaste beräkningsmetoderna och hade ett helt oberoende perspektiv mot tidigare uppskattningar. Beräkningsgruppen gjorde jämförande beräkningar med hjälp av nya program och dämpningsfunktioner (GMPE). Som regel användes tidigare seismiska zonindelningar, men rapakivi-området nära Lovisa var av särskilt intresse i känslighetsstudier. Den av beräkningsgruppen använda jordbävningskatalogen upprätthålls av Helsingfors universitet. Gutenberg-Richter-parametrar som beskriver seismiciteten och den tillämpade GMPE och dess anpassning till jordbävningsdata identifierades som de viktigaste parametrarna som orsakar osäkerheter i sannolikhetsbedömningar av jordbävningsrisk. Anledningen till detta är frånvaron av stora och även medelstora jordbävningar i Finland. Därför måste parametrarna uppskattas på basis av få observationer eller av jordbävningsdata från andra håll i världen, vilket inte nödvändigtvis är lämpligt för den hårda berggrunden i Finland. De högsta och lägsta gränsvärdena för jordbävningsstorlekar som används som parametrar i hasarduppskattningar har mindre betydelse. Saker som kan uteslutas från hasarduppskattningar i Finland är t.ex. jordförvätskning, jordmodellering och lokal markinducerad vibrationsförstärkning, eftersom hittills alla kärnkraftsanläggningar har byggts på berggrund. Denna bedömning stämmer inte nödvändigtvis om småskaliga modulära (SMR) anläggningar byggs på nya områden som kan ha annorlunda geologiska förhållanden. Jordbävningsexperter rekommenderar ytterligare forskning i Finland för att framta en nationell hasardkarta som stödjer placeringar av nya anläggningar och tillämpning av NGA-East GMPE eller utveckling av en finsk GMPE som bättre skulle motsvara lokala jordbävningsdata

Perception of pharmacological prevention and subsequent non-adherence to medication in patients with ischaemic heart disease:a population-based cohort study

OBJECTIVE: A patient-focused approach is advocated to embody risk of non-adherence to medication and subsequent adverse clinical outcomes following ischaemic heart disease (IHD). This study aimed to explore how patient perceived information on pharmacological prevention was associated with subsequent non-adherence to medication (measured by non-initiation, non-implementation and non-persistence) in patients with incident IHD. DESIGN: Cohort study. SETTING: Denmark. PARTICIPANTS: Register-based cohort of 829 patients with incident IHD in 2013. MEASURES: Perception covered whether patients’ experienced being adequately informed about their pharmacological prevention. Information on such was obtained from a survey and divided into ‘Well informed’, ‘Moderately informed’ and ‘Poorly informed’. Information on baseline characteristics, and reimbursed prescriptions of medication (antiplatelets, statins, ACE-inhibitors/angiotensin receptor blockers and β-blockers) during follow-up were obtained by linkage to nationwide public registers. Non-initiation and non-implementation of medication, measured as proportion of days covered, were analysed by Poisson regression. Non-persistence to medication, measured as risk of discontinuation, was analysed by multivariable Cox proportional hazard regression. PRIMARY AND SECONDARY OUTCOME MEASURES: Non-implementation and non-persistence to medication up to 365 days of follow-up were primary outcomes. Secondary outcomes included non-initiation as well as non-implementation and non-persistence to medication at 180 days of follow-up. RESULTS: A dose–response association was in general found between perception of pharmacological prevention and risk of non-implementation and non-persistence. For example, the hazard of non-persistence to antiplatelets was 1.18 (95% CI 0.71 to 1.96) times higher for patients reporting 'Moderately informed' and 1.89 (95% CI 1.10 to 3.25) times higher for patients reporting 'Poorly informed', compared with patients reporting 'Well informed of perception of pharmacological prevention' up to 365 days of follow-up. CONCLUSION: Lower levels of perception of pharmacological prevention were associated with subsequent non-implementation and non-persistence to medication in patients with incident IHD

THE VALIDITY OF MEASURING SKIPPING CADENCE WITH A NOVEL WEARABLE SENSOR - SINTEC SMART PATCH

The aim of this study was to test the validity of running cadence assessed with a novel smart patch designed within a SINTEC Horizon 2020 project. Participants performed 3 consecutive 20-seconds skipping with increasing intensity (slow, medium, fast). Cadence was derived from raw data from a “SINTEC” smart patch, Dytran accelerometers, and HBM bilateral force plates. Data from all devices were compared using Bland-Altman analysis and Wilcoxon signed-rank test. The mean bias between cadence measured with Dytran accelerometer and force plates with ‘’SINTEC’’ smart patch was 0.08 and -0.17 steps/min, respectively. In addition, there were no statistically significant difference between the mean cadence determined with different sensors/devices. Therefore, we can conclude that the measurement of cadence using a novel SINTEC smart patch showed good validity

Immunization and Aging: a Learning Process in the Immune Network

The immune system can be thought as a complex network of different interacting elements. A cellular automaton, defined in shape-space, was recently shown to exhibit self-regulation and complex behavior and is, therefore, a good candidate to model the immune system. Using this model to simulate a real immune system we find good agreement with recent experiments on mice. The model exhibits the experimentally observed refractory behavior of the immune system under multiple antigen presentations as well as loss of its plasticity caused by aging.Comment: 4 latex pages, 3 postscript figures attached. To be published in Physical Review Letters (Tentatively scheduled for 5th Oct. issue

A method for the reconstruction of unknown non-monotonic growth functions in the chemostat

We propose an adaptive control law that allows one to identify unstable steady states of the open-loop system in the single-species chemostat model without the knowledge of the growth function. We then show how one can use this control law to trace out (reconstruct) the whole graph of the growth function. The process of tracing out the graph can be performed either continuously or step-wise. We present and compare both approaches. Even in the case of two species in competition, which is not directly accessible with our approach due to lack of controllability, feedback control improves identifiability of the non-dominant growth rate.Comment: expansion of ideas from proceedings paper (17 pages, 8 figures), proceedings paper is version v