Katsaus putkivahvistinta käsittelevään kirjallisuuteen

Tiivistelmä. Työssä perehdytään putkivahvistimia käsittelevään kirjallisuuteen ja muihin lähdemateriaaleihin. Työn tavoitteena on selvittää, mitkä lähteet soveltuvat parhaiten putkivahvistimien perusteiden oppimateriaaliksi. Lisäksi työssä esitellään perusteet putkivahvistimista sekä tutustutetaan lukija pikaisesti yhteen putkivahvistin tyyppiin nimeltään SE/84 Brachycera 2.0 eli Kärpänen. Työtä kirjoittaessa havaittiin, että yhtä hyvää materiaalia aiheen opiskeluun ei liene olemassakaan. Eri aineistot keskittyvät eri näkökulmiin ja erityyppisiin vahvistimiin, joten opiskelumateriaalin valinta määräytyy pitkälti tarpeen perusteella ja siksi on mahdotonta löytää yhtä oikeaa ja hyvää materiaalia.Review of the literature about valve amplifiers. Abstract. The purpose of this document is to explore literature and other kinds of materials that covers information about the valve amplifiers. The goal is to find out convenient materials to study about valve amplifiers. From this document the reader gets also basic knowledge about valve amplifiers and gets a quick introduction to a valve amplifier example called SE/84 Brachycera 2.0. When writing this paper, it was noticed that there is no such material that would be perfect to study everything about valve amplifiers. Different materials concentrate on different point of views and different kinds of amplifiers so choosing the material depends mainly on the purpose and needs. That is why it is impossible to find the source which covers the topic conveniently

Älykkään liikenteen varoitusviestien kvanttiturvallinen allekirjoittaminen

Tiivistelmä. Älykkäässä liikenteessä ajoneuvot viestivät keskenään parantaen näin liikenteen sujuvuutta ja turvallisuutta. Viestinnän luotettavuus taataan digitaalisilla allekirjoituksilla, jotka varmistavat viestien aitouden ja alkuperän. Nykyisten digitaalisten allekirjoitusten luotettavuus on vaarassa kvanttitietokoneiden kehityksen myötä, koska kvanttitietokoneen avulla niiden taustalla olevien matemaattisten ongelmien ratkaisu helpottuu huomattavasti. On kuitenkin olemassa myös kvanttiturvallisia allekirjoitusalgoritmeja, joilla tuotetut allekirjoitukset eivät ole alttiita kvanttitietokoneella toteutetuille hyökkäyksille. Tässä diplomityössä liitettiin älykkään liikenteen varoitusviesteihin kvanttiturvallinen allekirjoitus. Toteutuksen pohjana toimivat älykkään liikenteen viestintää määrittävät eurooppalaiset tekniset spesifikaatiot ja kolmen kvanttiturvallisen allekirjoitusalgoritmin valmiit toteutukset. Näitä yhdistelemällä luotiin ohjelma, jossa älykkään liikenteen varoitusviestit allekirjoitetaan kvanttiturvallisesti. Kunkin kvanttiturvallisen allekirjoitusalgoritmin soveltuvuutta liikennekäyttöön arvioitiin vertaamalla sitä nykyisin käytössä oleviin allekirjoitusalgoritmeihin. Vertailussa huomioitiin allekirjoitukseen ja varmennukseen tarvittava aika sekä syntyneiden viestien koko. Tuloksista nähdään, että vertaillut allekirjoitusalgoritmit eroavat toisistaan sekä suoritusnopeuden että syntyneiden viestien koon puolesta. Tulosten perusteella kvanttiturvallisia allekirjoitusalgoritmeja voitaisiin käyttää älykkäässä liikenteessä ilman, että viestien käsittelynopeus kärsisi kohtuuttomasti.Quantum-safe signing of notification messages sent by intelligent transport systems. Abstract. Intelligent transport systems improve safety and fluency in traffic by utilizing communication between vehicles. Reliability of this communication is ensured by digital signatures which confirm origin and authenticity of the sent messages. Digital signature algorithms used today are at risk since quantum computers are being developed and could be used to solve mathematical problems underlying these algorithms. However, quantum-safe digital signature algorithms which cannot be broken even by attacks of quantum computers do exist. In this master’s thesis, quantum-safe digital signatures are integrated into notification messages used by intelligent transport systems. The program implemented is based on reference implementations of three quantum-safe digital signature algorithms and European technical specifications regarding communication between intelligent transport systems. By integrating these, a new implementation is constructed, where notification messages are signed using quantum-safe digital signature algorithms. Their suitability for this use is evaluated by measuring their speed and the size of the signed messages, and comparing them with the algorithms used today. The results show that these quantum-safe algorithms perform differently with regard to time required to sign and verify the sent messages as well as the size of these messages. Based on these results, quantum-safe digital signature algorithms could be used by intelligent transport systems with only moderate changes to performance

EDA-signaalin automaattinen virheensuodatus

Tiivistelmä. Tässä kandidaatintyössä tutkin ihmiskehosta mitatun sähkönjohtavuussignaalin eli EDA-signaalin automaattista virheensuodatusta. EDA-signaali on kytköksissä ihmisen parasympaattiseen hermostoon, joten sen avulla voidaan tulkita ihmisen tunnetiloja ja vireystilaa. Tavallinen EDA-signaali etenee muutaman sekunnin mittaisissa nousevissa ja laskevissa aalloissa. Tässä tutkielmassa käyttämäni data on kerätty Empatica E4 -rannekkeella, joka mittaa EDA-signaalin lisäksi myös kiihtyvyysdataa. Koska mittalaite asetetaan koehenkilön käteen, se on altis henkilön liikkeiden aiheuttamille virheille. Nämä virheet saattavat näkyä signaalissa sekä nollaan pudonneena signaalina että epätavallisen jyrkkinä piikkeinä. EDA-signaalin keräämistä, sen ongelmia ja virheensuodatusta on käsitelty kirjallisuudessa ja siihen on esitetty erilaisia ratkaisuja. Tässä tutkielmassa käyn läpi aiheeseen liittyviä artikkeleita ja esittelen muutamia ratkaisuehdotuksia virhepiikkien eli niin sanottujen artefaktien automaattiseksi tunnistamiseksi. Esittelen myös oman ratkaisuni, joka perustuu signaalin pätkien luokitteluun normaaleiksi tai todennäköisesti virheellisiksi muodon ja amplitudin perusteella. Leimoja on neljää eri tyyppiä: 0 — normaalia signaalia; 1 — signaali on pudonnut alle minimiamplitudin; 2 — signaalissa on liikkumisesta johtuva jyrkkä piikki; ja 3 — signaalissa on tuntemattomasta syystä johtuva jyrkkä piikki. Luokittelussa käytetään apuna EDA-signaalin kanssa samanaikaisesti kerättyä kiihtyvyysdataa. Analysoitu ja luokiteltu signaali esitetään graafisesti väriä leiman mukaan vaihtavalla viivalla. Esittelen lyhyesti ohjelmani tuottamia tuloksia ja arvioin niiden oikeellisuutta. Lopuksi esitän ehdotuksia siitä, kuinka työtä voisi jatkaa, ja arvioin ratkaisematta jääneitä ongelmia.Automatic error detection in EDA signal. Abstract. This is a bachelor’s thesis on automatic detection of artefacts in EDA signal (Electodermal Activity). EDA measures electrical characteristics of human skin. These characteristics are connected to the parasympathetic nerve system and thus they reflect emotions and arousal of the person being monitored. My data is collected using Empatica E4 wristband and it consists of several hours of EDA and acceleration data from three different days. Wristbands are liable to errors due to rapid movement of the test person, and these errors can be seen in the signal as steep peaks or very low amplitude level. Filtering these errors from EDA signal has been discussed in several articles, many of which also provide solutions to this problem. In this thesis I present some of these articles. I also suggest my own solution, which is a Python program that measures amplitude and derivative of the signal. Concurrently gathered acceleration data is used in determining whether the signal is erroneous due to rapid movements of the test person. Every sample of the signal is being labeled based on these properties. There are four different labels: 0 — normal signal; 1 — amplitude of the signal is too low; 2 — fast change in signal level due to movement of the test person; and 3 — fast change in signal level due to unknown reason. The program creates metadata, which contains information about proportions of the different labels. Lastly, labeled signal is presented as a multicoloured line. After discussing my methodology I present and assess the results yielded by my program. In the last section I discuss unsolved problems and propose possible themes for future work

Accumulation of 99mTc-low-density lipoprotein in human malignant glioma.

Low-density lipoprotein (LDL) uptake in gliomas was studied to find out if LDL has potential as a drug carrier of boron, especially for boron neutron capture therapy. Single photon emission tomography (SPET) was performed 2 h and 20 h after intravenous injection of autologous 99mTc-labelled LDL in four patients with untreated and five patients with recurrent glioma. 99mTc-LDL uptake was compared with the uptake of 99mTc-labelled human serum albumin (HSA), an established blood pool marker. The intra- and peritumoral distributions of radioactivity in the SPET images were not identical for radiolabelled LDL and HSA. The mean LDL tumour to brain ratio, determined from transversal SPET slices at 20 h post injection, was 1.5 in untreated and 2.2 in recurrent gliomas; the corresponding ratios for HSA were 1.6 and 3.4. The brain to blood ratio remained constant at 2 h and 20 h in both types of tumours. These data are not consistent with highly selective, homogeneous uptake of LDL in gliomas. However, the different tumoral distribution and rate of uptake of 99mTc-LDL, as compared with 99mTc-HSA, indicate that the uptake of LDL is different from that of HSA and that further studies on the mechanism of LDL uptake in glioma are warranted

The socio-demographic patterning of sexual risk behaviour: a survey of young men in Finland and Estonia

<p>Abstract</p> <p>Background</p> <p>Sexually transmitted infections (STIs) among the youth are an increasing challenge for public health in Europe. This study provided estimates of men's (18–25 years) sexual risk behaviour and self-reported STIs and their socio-demographic patterning in Finland and Estonia; two countries that are geographically close, but have very different STI epidemics.</p> <p>Method</p> <p>Nationally representative cross-sectional population surveys with comparable survey questions were used. Data from self-administered questionnaires for 1765 men aged 18–25 years in Finland (85% of the age cohort was included in the sampling frame, 95% of the sample responded) and 748 in Estonia, with a response rate of 43% respectively, were analysed. Socio-demographic patterning of multiple partners, condom use and self-reported STIs are presented was studied using multiple logistic regression analysis.</p> <p>Results</p> <p>The main findings focus on associations found within each country. In Finland, higher age, low education and to a lesser extent relationship with a non-steady partner increased the likelihood of reporting multiple lifetime-partners, while in Estonia only higher age and low education revealed this effect. In relation to unprotected intercourse, in Finland, higher age, low education and relationship status with a steady partner increased the likelihood of reporting unprotected intercourse. In Estonia, the same was observed only for relationship status. In Finland the likelihood of self-reported STIs increased by older age and lower education and decreased by being with a non-steady partner, while in Estonia, a non-significant increase in self-reported STIs was observed only in the older age group.</p> <p>Conclusion</p> <p>A clear socio-demographic patterning for sexual behaviour and self-reported STIs was revealed in Finland, but a less consistent trend was seen in Estonia. The findings of this study suggest that prevention strategies should focus in Finland on less educated singles and in Estonia on young men generally.</p

What is the potential for replacing monocultures with mixed-species stands to enhance ecosystem services in boreal forests in Fennoscandia?

The boreal forests of Fennoscandia are largely dominated by Norway spruce and Scots pine. Conifer monocultures have been favoured in forest management during the last decades. Recently, concern has risen that forests consisting of only one tree species could be vulnerable to biotic damage. Additionally, environmental and societal changes are placing new demands on forest utilization, thus shifting the focus to alternative forest management options providing a wider scale of ecosystem services. It has been proposed that mixed forests are better than monocultures with respect to biodiversity, risk management and recreational value. By synthesising research studies, we provide an overview of current knowledge on how to combine wood production and other ecosystem services in mixed boreal forests in Fennoscandia. We addressed the following questions in more detail: what are the effects of mixed forests on soil properties, understorey vegetation, biodiversity, wildlife, resistance to and resilience against damage, forest productivity and the multiple use of forests? Furthermore, what are the silvicultural possibilities for establishing and managing mixed forests?Based on this review, mixed forests appear to provide a higher output of most ecosystem goods and services, including higher biodiversity and improved risk management, soil properties and multiple-use values. The most serious challenge is the browsing by cervids, which damages sapling stands. There is potential to establish single-storied mixed forests with current regeneration methods and material. Further research is particularly needed on the silvicultural practices suited for mixed boreal forests

Palaeoclimatic conditions in the Mediterranean explain genetic diversity of Posidonia oceanica seagrass meadows

Past environmental conditions in the Mediterranean Sea have been proposed as main drivers of the current patterns of distribution of genetic structure of the seagrass Posidonia oceanica, the foundation species of one of the most important ecosystems in the Mediterranean Sea. Yet, the location of cold climate refugia (persistence regions) for this species during the Last Glacial Maximum (LGM) is not clear, precluding the understanding of its biogeographical history. We used Ecological Niche Modelling together with existing phylogeographic data to locate Pleistocene refugia in the Mediterranean Sea and to develop a hypothetical past biogeographical distribution able to explain the genetic diversity presently found in P. oceanica meadows. To do that, we used an ensemble approach of six predictive algorithms and two Ocean General Circulation Models. The minimum SST in winter and the maximum SST in summer allowed us to hindcast the species range during the LGM. We found separate glacial refugia in each Mediterranean basin and in the Central region. Altogether, the results suggest that the Central region of the Mediterranean Sea was the most relevant cold climate refugium, supporting the hypothesis that long-term persistence there allowed the region to develop and retain its presently high proportion of the global genetic diversity of P. oceanica.Fundacao para a Ciencia e a Tecnologia (FCT, Portugal) [SFRH/BPD/85040/2012]; FCT [UID/Multi/04326/2013, FCT-BIODIVERSA/004/2015]; Pew foundation (USA)info:eu-repo/semantics/publishedVersio