Phase-coded pulse aperiodic transmitter coding

Both ionospheric and weather radar communities have already adopted the method of transmitting radar pulses in an aperiodic manner when measuring moderately overspread targets. Among the users of the ionospheric radars, this method is called Aperiodic Transmitter Coding (ATC), whereas the weather radar users have adopted the term Simultaneous Multiple Pulse-Repetition Frequency (SMPRF). When probing the ionosphere at the carrier frequencies of the EISCAT Incoherent Scatter Radar facilities, the range extent of the detectable target is typically of the order of one thousand kilometers – about seven milliseconds – whereas the characteristic correlation time of the scattered signal varies from a few milliseconds in the D-region to only tens of microseconds in the F-region. If one is interested in estimating the scattering autocorrelation function (ACF) at time lags shorter than the F-region correlation time, the D-region must be considered as a moderately overspread target, whereas the F-region is a severely overspread one. Given the technical restrictions of the radar hardware, a combination of ATC and phase-coded long pulses is advantageous for this kind of target. We evaluate such an experiment under infinitely low signal-to-noise ratio (SNR) conditions using lag profile inversion. In addition, a qualitative evaluation under high-SNR conditions is performed by analysing simulated data. The results show that an acceptable estimation accuracy and a very good lag resolution in the D-region can be achieved with a pulse length long enough for simultaneous E- and F-region measurements with a reasonable lag extent. The new experiment design is tested with the EISCAT Tromsø VHF (224 MHz) radar. An example of a full D/E/F-region ACF from the test run is shown at the end of the paper

The F-region trough: seasonal morphology and relation to interplanetary magnetic field

We present here the results of a statistical study of the ionospheric trough observed in 2003 by means of satellite tomography. We focus on the seasonal morphology of the trough occurrence and investigate the trough latitude, width and the horizontal gradients at the edges, at different magnetic local times, as well as their relations to geomagnetic activity and the interplanetary magnetic field. A seasonal effect is noticed in the diurnal variation of the trough latitude, indicating that summer clearly differs from the other seasons. In winter the troughs seem to follow the solar terminator. The width of the trough has a diurnal variation and it depends on the season, as well. The broadest troughs are observed in winter and the narrowest ones in summer. A discontinuity in the diurnal variation of the trough latitude is observed before noon. It is suggested that this is an indication of a difference between the generation mechanisms of morningside and eveningside troughs. The density gradients at the edges have a complex dependence on the latitude of the trough and on geomagnetic activity. The photoionization and the auroral precipitation are competing in the formation of the trough walls at different magnetic local times. An important finding is that the interplanetary magnetic field plays a role in the occurrence of the trough at different levels of geomagnetic activity. This is probably associated with the topology of the polar cap convection pattern, which depends on the directions of the IMF components <i>B<sub>y</sub></i> and <i>B<sub>z</sub></i>

Älyn, järjen ja toiminnan kemia: Sir Kenelm Digbyn ja George Starkeyn itsemuotoilu alkemisteina 1600-luvun Englannissa

Tiivistelmä. Tutkielma käsittelee alkemistin persoonan räätälöintiä, niin kutsuttua itsemuotoilua, 1600-luvun puolivälin Englannissa. Se lähestyy aihetta kahden Lontoossa vaikuttaneen esimerkkihenkilön, amerikkalaissyntyisen George Starkeyn sekä englantilaisen aatelisen Sir Kenelm Digbyn kautta. Sen tarkoitus on avata, millaisia ihanteita alkemistin persoonalle aikanaan asetettiin, ja millä tavoin nämä kaksi henkilöä pyrkivät representoimaan itsensä alkemisteina sekä suhteessa alkemiaan. Lisäksi se käsittelee filosofian ja alkemian suhdetta sekä näihin kuuluvien persoonien suhdetta. Työ hyödyntää alkuperäislähteinään sen käsittelemien henkilöiden alkemiaa, filosofiaa ja teologiaa käsitteleviä teoksia. Lähteet ovat EEBO-tietokannasta löytyviä digitoituja aineistoja, joista keskeisimmät ovat Starkeyn Pyrotechny Asserted and Illustrated ja Nature’s Explication and Helmont’s Vindication sekä Digbyn Two Treatises, A Late Assembly ja A Discourse Concerning the Infallibility of Religion. Tutkielma lähestyy aihetta aineistoanalyysin ja retorisen analyysin metodien kautta. Tutkielma osoittaa alkemian moninaisen ja monitulkintaisen aseman aikansa yhteiskunnassa. Samalla se valottaa loogisen järjen ja intuitiivisen älyn merkitystä alkemistin ja filosofin persoonille sekä näihin liittyvien aristoteelisten ja uusplatonisten vaikutteiden merkitystä ja asemaa edellä mainituille kentillä. Hyödyntäen alkuperäislähteitä tutkimus demonstroi, miten Starkey pyrki luomaan itselleen persoonan intuitiivisena ja älyllisenä adeptina, kun taas Digby tavoitteli Aristoteleeseen sekä uuteen, ennen kaikkea kartesiolaiseen, filosofiaan nojaavaa järjellisen filosofin persoonaa. Lisäksi se valottaa protestanttisen ja katolisen uskon luomia sävyeroja alkemistin ja luonnonfilosofin persoonissa sekä yhteiskunnallisen aseman tuomia eroja tieteellisessä ja filosofisessa toiminnassa. Tulosten pohjalta on mahdollista havaita, miten kokeellisen tiedontuotannon metodit saattoivat erota toisistaan voimakkaallakin tavalla varhaismodernin alkemian kontekstissa. Lisäksi niiden kautta on nähtävissä, miten erilaiset olosuhteet ja vaikutteet loivat erilaisia suhtautumistapoja ja käsityksiä esimerkiksi totuuden ja tiedon luonteesta. Näiden kohdalla ennen kaikkea erottelu ainoastaan henkilökohtaisen kokemuksen kautta saavutettavissa olevan ja kielellisesti jaettavan tiedon välillä tulee esiin

Reconstructing solar magnetic fields from historical observations : IV. Testing the reconstruction method.

Abstract Aims. The evolution of the photospheric magnetic field has only been regularly observed since the 1970s. The absence of earlier observations severely limits our ability to understand the long-term evolution of solar magnetic fields, especially the polar fields that are important drivers of space weather. Here, we test the possibility to reconstruct the large-scale solar magnetic fields from Ca II K line observations and sunspot magnetic field observations, and to create synoptic maps of the photospheric magnetic field for times before modern-time magnetographic observations. Methods. We reconstructed active regions from Ca II K line synoptic maps and assigned them magnetic polarities using sunspot magnetic field observations. We used the reconstructed active regions as input in a surface flux transport simulation to produce synoptic maps of the photospheric magnetic field. We compared the simulated field with the observed field in 1975−1985 in order to test and validate our method. Results. The reconstruction very accurately reproduces the long-term evolution of the large-scale field, including the poleward flux surges and the strength of polar fields. The reconstruction has slightly less emerging flux because a few weak active regions are missing, but it includes the large active regions that are the most important for the large-scale evolution of the field. Although our reconstruction method is very robust, individual reconstructed active regions may be slightly inaccurate in terms of area, total flux, or polarity, which leads to some uncertainty in the simulation. However, due to the randomness of these inaccuracies and the lack of long-term memory in the simulation, these problems do not significantly affect the long-term evolution of the large-scale field

Long-term effects of smoking on tooth loss after cessation among middle-aged Finnish adults: the Northern Finland Birth Cohort 1966 Study

Abstract Background Despite smoking cessation efforts, cigarette smoking remains a serious general and oral health problem. We aimed to investigate the putative benefits of smoking cessation on dentition and to analyse whether the time elapsed since smoking cessation associated positively with the remaining number of teeth. Methods This cross-sectional study analyses data from the 46-year follow-up of the Northern Finland Birth Cohort Study 1966 (NFBC1966). A total of 5 540 subjects participated in this cross-sectional study, which utilises both clinical dental examinations and mailed questionnaires. We used the following information on smoking: status (current, former, never), years of smoking (current, former) and years elapsed since smoking cessation (former). Self-reported and clinically measured number of teeth (including third molars) served as alternative outcomes. We used binary logistic regression models to analyse the dichotomised number of teeth (‘0–27’, ’28–32’) and then calculated unadjusted and adjusted odds ratios (OR) with 95 % confidence intervals (CI) for the smoking variables (never smoker as the reference). Gender, education, tooth brushing frequency, diabetes and alcohol use served as confounders for the adjusted models. Results Ten years or more of smoking associated with tooth loss; this effect was the strongest among men who reported having an ongoing smoking habit (self-reported outcome: adjusted OR = 1.74, CI = 1.40–2.16) and the weakest among women classified as former smokers (self-reported outcome: adjusted OR = 1.27, CI = 1.00–1.62). Conclusions This study shows that smoking has long-term effects on tooth loss even after cessation. The findings support smoking cessation efforts to reduce oral health risks

Frequent consumption of sugar-sweetened beverages and sweets starts at early age

Objectives: We aimed to investigate the habitual consumption of sugar-sweetened beverages (SSBs) and sweets in relation to mothers' behaviours and practices with their infants. Methods: We targeted mothers with children 1-24 months (N=200) visiting Public Child Health clinics in Finland. During routine visits mothers (N=179) volunteered to complete a self-administered anonymous questionnaire about their child's health-related behaviours (consumption of sweets and SSBs, tooth brushing frequency). The questionnaires also included questions about the mothers' background (age, education) and health-related behaviours (consumption of sweets, tooth brushing frequency and smoking habits). The children were categorised by age, and Chi-squared tests, Fischer's exact test, ANOVA and correlation coefficient served for the statistical analyses. Results: Of those under 6 months, almost half (44%) received SSBs, and 45% of them more than once a week. Their use gradually increased by age such that by 19-24 months, all received SSBs at least sometimes, and 56%, frequently. Fewer than half of the mothers (33-43%) gave sweets to their children between the ages of 10-15 months, but 92% by the age of 2 years. Children's twice-a-day tooth brushing increased from 14% to 33%. The child's age and tooth brushing frequency correlated with the consumption of sugar-sweetened products (r=0.458). Conclusions: Infants frequent consumption of sugar-sweetened products begins early in childhood. Thus, tackling these common risk factors in the first years of life is essential and calls for health-promoting actions in multiple areas that target primarily the parents of infants.Peer reviewe