Developing Peer-To-Peer Web Applications

As the virtual world grows more complex, finding a standard way for storing data becomes increasingly important. Ideally, each data item would be brought into the computer system only once. References for data items need to be cryptographically verifiable, so the data can maintain its identity while being passed around. This way there will be only one copy of the users family photo album, while the user can use multiple tools to show or manipulate the album. Copies of users data could be stored on some of his family members computer, some of his computers, but also at some online services which he uses. When all actors operate over one replicated copy of the data, the system automatically avoids a single point of failure. Thus the data will not disappear with one computer breaking, or one service provider going out of business. One shared copy also makes it possible to delete a piece of data from all systems at once, on users request. In our research we tried to find a model that would make data manageable to users, and make it possible to have the same data stored at various locations. We studied three systems, Persona, Freenet, and GNUnet, that suggest different models for protecting user data. The main application areas of the systems studied include securing online social networks, providing anonymous web, and preventing censorship in file-sharing. Each of the systems studied store user data on machines belonging to third parties. The systems differ in measures they take to protect their users from data loss, forged information, censorship, and being monitored. All of the systems use cryptography to secure names used for the content, and to protect the data from outsiders. Based on the gained knowledge, we built a prototype platform called Peerscape, which stores user data in a synchronized, protected database. Data items themselves are protected with cryptography against forgery, but not encrypted as the focus has been disseminating the data directly among family and friends instead of letting third parties store the information. We turned the synchronizing database into peer-to-peer web by revealing its contents through an integrated http server. The REST-like http API supports development of applications in javascript. To evaluate the platform’s suitability for application development we wrote some simple applications, including a public chat room, bittorrent site, and a flower growing game. During our early tests we came to the conclusion that using the platform for simple applications works well. As web standards develop further, writing applications for the platform should become easier. Any system this complex will have its problems, and we are not expecting our platform to replace the existing web, but are fairly impressed with the results and consider our work important from the perspective of managing user data.

Developing Peer-To-Peer Web Applications

As the virtual world grows more complex, finding a standard way for storing data becomes increasingly important. Ideally, each data item would be brought into the computer system only once. References for data items need to be cryptographically verifiable, so the data can maintain its identity while being passed around. This way there will be only one copy of the users family photo album, while the user can use multiple tools to show or manipulate the album. Copies of users data could be stored on some of his family members computer, some of his computers, but also at some online services which he uses. When all actors operate over one replicated copy of the data, the system automatically avoids a single point of failure. Thus the data will not disappear with one computer breaking, or one service provider going out of business. One shared copy also makes it possible to delete a piece of data from all systems at once, on users request. In our research we tried to find a model that would make data manageable to users, and make it possible to have the same data stored at various locations. We studied three systems, Persona, Freenet, and GNUnet, that suggest different models for protecting user data. The main application areas of the systems studied include securing online social networks, providing anonymous web, and preventing censorship in file-sharing. Each of the systems studied store user data on machines belonging to third parties. The systems differ in measures they take to protect their users from data loss, forged information, censorship, and being monitored. All of the systems use cryptography to secure names used for the content, and to protect the data from outsiders. Based on the gained knowledge, we built a prototype platform called Peerscape, which stores user data in a synchronized, protected database. Data items themselves are protected with cryptography against forgery, but not encrypted as the focus has been disseminating the data directly among family and friends instead of letting third parties store the information. We turned the synchronizing database into peer-to-peer web by revealing its contents through an integrated http server. The REST-like http API supports development of applications in javascript. To evaluate the platform s suitability for application development we wrote some simple applications, including a public chat room, bittorrent site, and a flower growing game. During our early tests we came to the conclusion that using the platform for simple applications works well. As web standards develop further, writing applications for the platform should become easier. Any system this complex will have its problems, and we are not expecting our platform to replace the existing web, but are fairly impressed with the results and consider our work important from the perspective of managing user data.

World Wide Web korpuksena kielitieteellisen tutkimusaineiston haku verkkosivuilta

Tämä tutkielma käsittelee World Wide Webin sisältämien verkkosivujen sisältöjen käyttöä korpusmaisesti kielitieteellisenä tutkimusaineistona. World Wide Web sisältää moninkertaisesti enemmän tekstiä kuin suurimmat olemassa olevat perinteiset tekstikorpukset, joten verkkosivuilta voi todennäköisesti löytää paljon esiintymiä sellaisista sanoista ja rakenteista, jotka ovat perinteisissä korpuksissa harvinaisia. Verkkosivuja voidaan käyttää aineistona kahdella eri tavalla: voidaan kerätä satunnainen otos verkkosivuista ja luoda itsenäinen korpus niiden sisällöistä, tai käyttää koko World Wide Webiä korpuksena verkkohakukoneiden kautta. Verkkosivuja on käytetty tutkimusaineistona monilla eri kielitieteen aloilla, kuten leksikograafisessa tutkimuksessa, syntaktisten rakenteiden tutkimuksessa, pedagogisena materiaalina ja vähemmistökielten tutkimuksessa. Verkkosivuilla on perinteisiin korpuksiin verrattuna useita haitallisia ominaisuuksia, jotka pitää ottaa huomioon, kun niitä käytetään aineistona. Kaikki sivut eivät sisällä kelvollista tekstiä, ja sivut ovat usein esimerkiksi HTML-muotoisia, jolloin ne pitää muuttaa helpommin käsiteltävissä olevaan muotoon. Verkkosivut sisältävät enemmän kielellisiä virheitä kuin perinteiset korpukset, ja niiden tekstityypit ja aihepiirit ovat runsaslukuisempia kuin perinteisten korpusten. Aineiston keräämiseen verkkosivuilta tarvitaan tehokkaita ohjelmatyökaluja. Näistä yleisimpiä ovat kaupalliset verkkohakukoneet, joiden kautta on mahdollista päästä nopeasti käsiksi suureen määrään erilaisia sivuja. Näiden lisäksi voidaan käyttää erityisesti kielitieteellisiin tarpeisiin kehitettyjä työkaluja. Tässä tutkielmassa esitellään ohjelmatyökalut WebCorp, WebAsCorpus.org, BootCaT ja Web as Corpus Toolkit, joiden avulla voi hakea aineistoa verkkosivuilta nimenomaan kielitieteellisiin tarkoituksiin.

Verkko-oppimateriaalin multimodaalisuus : kohteena YLEn Kansalaisen ABC -verkko-oppimateriaalit

Today information and communication technology allows us to use multimedia more than ever before in e-learning materials. Multimedia though can increase cognitive load in learning process. Because of that it cannot be taken granted what kind of learning materials should be produced. This paper intended to study the diversity of e-learning materials and the factors related cognitive load. The main purpose was to study the multimodality of the multimedia learning materials. The subject of this study is the learning materials on the web site Kansalaisen ABC published by YLE. Learning materials in the web site were approached from three different perspectives. The specific questions were: (1) What kind of form features are used in the representations of the learning material? Are certain form features preferred over others? (2) How do the cognitive load factors take shape in learning materials and between the forms? (3) How does the multimodality phenomenon appear in the learning materials and in what ways are form features and cognitive load factors related to multimodality? In this case study a qualitative approach was used. Analysis of the form features and the cognitive load factors in learning materials were based on content analysis. Form features included the specification of a format, the structure, the interactivity type and the type of learning material. The results showed that the web sites include various representations of both verbal and visual forms. Cognitive load factors were related mostly to visual than verbal material. Material presented according to the principles of cognitive multimedia theory multimedia representations did not cause cognitive overload in the informants. Cognitive load was increased in the case of students needing to split their attention between the multimedia forms in time and place. The results indicated how different individual characteristics are reflected by the cognitive load factors.

Sense of Community in Web Environment

The study of social phenomena in the World Wide Web has been rather fragmentary, andthere is no coherent, reseach-based theory about sense of community in Web environment. Sense of community means part of one's self-concept that has to do with perceiving oneself belonging to, and feeling affinity to a certain social grouping. The present study aimed to find evidence for sense of community in Web environment, and specifically find out what the most critical psychological factors of sense of community would be. Based on known characteristics of real life communities and sense of community, and few occational studies of Web-communities, it was hypothesized that the following factors would be the most critical ones and that they could be grouped as prerequisites, facilitators and consequences of sense of community: awareness and social presence (prerequisites), criteria for membership and borders, common purpose, social interaction and reciprocity, norms and conformity, common history (facilitators), trust and accountability (consequences). In addition to critical factors, the present study aimed to find out if this kind of grouping would be valid. Furthermore, the effect of Web-community members' background variables to sense of community was of interest. In order to answer the questions, an online-questionnaire was created and tested. It included propositions that reflect factors that precede, facilitate and follow the sense of community in Web environment. A factor analysis was calculated to find out the critical factors and analyses of variance were calculated to see if the grouping to prerequisites, facilitators and consequences was right and how the background variables would affect the sense of community in Web environment. The results indicated that the psychological structure of sense of community in Web environment could not be presented with critical variables grouped as prerequisites, facilitators and consequences. Most factors did facilitate the sense of community, but based on this data it could not be argued that some of the factors chronologically precedesense of community and some follow it. Instead, the factor analysis revealed that the most critical factors in sense of community in Web environment are 1) reciprocal involvement, 2) basic trust for others, 3) similarity and common purpose of members, and 4) shared history of members. The most influencing background variables were the member's own participation activity (indicated with reading and writing messages) and the phase in membership lifecycle (from visitor to leader). The more the member participated and the further in membership life cycle he was, the more he felt sense of community. There are many descreptions of sense of community, but the present study was one of the first to actually measure the phenomenon in Web environment, and that gained well documented, valid results based on large data, proving that sense of community in Web environment is possible, and clarifying its psychological structure, thus enhancing the understanding of sense of community in Web environment. Keywords: sense of community, Web-community, psychology of the Internet

Ongelmana yhteistyökyvyttömyys? : Teoreettisen ymmärryksen etsintää web-avusteiselle tiedontuottamisyhteistyölle

Tutkimuksessa analysoidaan teoriatasolla web-avusteisen tiedontuottamisyhteistyön kokeilutoiminnassa esiin tulleita ongelmia ja kootaan niiden viitoittamana teoriaperustaa tulevaisuuden työskentelytavalle, tietämyksen web-avusteiselle ryhmäprosessoinnille. Keskiössä on ihminen kognitiivisena tiedonkäsittelijänä ja elinikäisenä oppijana. Organisaatiossa vallitsevat toimintastrategiat, ryhmätyöskentelyn organisointi ja ryhmässä toteutuvat käytännöt muodostavat yksilön toimintaa ohjaavan sosiaalisen toimintaympäristön, joka säätelee yhteistyöprosessin onnistumista. Yhteistyötä tarkastellaan sosiaalisen tiedonkäsittelyn ryhmäilmiönä, jossa käsite yhteistyökyky kyseenalaistuu. Tuotetussa teoriaperustassa ihminen nähdään monitasoisten oppimishaasteiden ristitulessa. Koulutuksessa vallitseva absoluuttinen tietokäsitys on pystyttävä muuttamaan konstruktivistiseksi tietokäsitykseksi: yhteistä tietämystä ryhmänä tuotettaessa yksilöiden tietämys on rakennusaineena. Koulussa saatu sosiaalisen tiedonkäsittelyn malli, itsekeskeisen tiedonkäsittelyn malli, ei sovellu tietämyksen ryhmäprosessointiin. Malliin liittyviä oppeja on poisopittava samalla kun ryhmäjäsenenä on suunniteltava ja yhdessä opeteltava ryhmäkeskeisiä ja web-avusteisia tiedonkäsittelymalleja. Näin yhteistyöprosessissa toteutuu rinnakkain asiaoppimista ja toimintaoppimista. Näitä molempia on tarpeen tukea kehitettäessä uudenlaisia web-avusteisia työskentelymenetelmiä. Osassa I esitellään tutkimuksen kokemusperäisiä virikkeitä. Suhteellisen tietokäsityksen mukaisesti tämä tutkimus on kiinteästi kytkeytynyt tutkijan elinikäiseen oppimiseen ja tutkimus kuvataan tutkijan yksilöllisen tietämyksen prosessointina. Tutkimusaiheen löytymiseen johtaneet käytännön havainnot aloittavat sen takia raportoinnin. Erityisesti koulun sosiaalisen tiedonkäsittelyn organisointi on tarkastelun kohteena. Osassa II hahmotetaan tutkimusnäkökulmaa. Tutkimuskysymykset ovat lähinnä viitoittamassa tietämyksen etsintää. Tutkimusmenetelmä, kokeilutoiminnan analysointi, on saanut vahvasti vaikutteita toimintatutkimuksesta. Tutkimusasetelman perustana on toimintaan kytkeytyvä ihmiskäsitys. Kirjallisuuden avulla etsitään mahdollisia kytkeytymiä ihmisen käyttäytymisen ja sosiaalisen toiminnan organisoinnin välillä. Osa III kuvailee tutkimusaihetta koskevan ymmärryksen prosessointia. Esiymmärrys yhteistyöstä ja yhteistyökäsitteen määrittely mahdollistavat kokeilutoimintaan ryhtymisen. Uusi viestintämahdollisuus (www) nähdään yhteisessä tiedonkäsittelyssä apuvälineenä. Käytännön kokeilujaksot tarjoavat aineksia kognitiivisen tiedonkäsittelyn syvällisten periaatteiden löytymiselle. Inhimillinen toiminta ja sosiaalinen tiedonkäsittely saavat teoriatason analysoinnissa oppimiseen perustuvia tulkintoja. Osassa IV esitellään tutkimuksen tavoitteena ollutta teoriaperustaa tietämyksen web-avusteiselle ryhmäprosessoinnille. Teoriatiivistelmässä keskiöön nousee ihmisen kognitiivinen tiedonkäsittely sekä konstruktivistisen asiaoppimisen että selviytymispainotteisen toimintaoppimisen muodossa. Sosiaalinen toimintaympäristö nähdään osallisena kognitiivisessa tiedonkäsittelyssä ja selityksenä sille, että yhteinen tiedonkäsittely ei onnistu pelkästään tietoverkkoympäristössä vaan tarvitaan myös sosiaalisia tapaamisia. Kokeilutoiminnan opetuksia tuodaan esille yhteistyöprosessin keskeisten tapahtumien tarkastelussa. Tuotettua teoriaperustaa koetellaan tieteen kentällä vertailemalla sitä muiden tutkijoiden julkaisemiin käsityksiin. Tietoverkkoteknologian suhdetta inhimilliseen tiedonkäsittelyyn verrataan muualla saatuihin ja julkaistuihin käsityksiin. Avainsanat: tietointensiivinen yhteistyö, tiedontuottamisyhteistyö, yhteistyöprosessi, yhteistyökyky, yhteistyökyvyttömyys, virtuaalinen yhteistyöorganisaatio, yksilöllinen tietämys, yhteisen ymmärryksen etsintä, yhteinen tietämys, kognitiivinen tiedonkäsittely, asiaoppiminen, toimintaoppiminen, sosiaalinen tiedonkäsittely, sosiaalinen toimintaympäristö, automatisoitunut toimintamalli, yksilökeskeinen toimintamalli, itsekeskeinen toimintamalli, ryhmäkeskeinen toimintamalli, sosiaalisen tiedonkäsittelyn toimintastrategia, työympäristössä oppiminen.

Characterization of the mitochondrial active-site serine protein LACTB: filaments in the mitochondrial intermembrane space

Mitochondria have evolved from endosymbiotic alpha-proteobacteria. During the endosymbiotic process early eukaryotes dumped the major component of the bacterial cell wall, the peptidoglycan layer. Peptidoglycan is synthesized and maintained by active-site serine enzymes belonging to the penicillin-binding protein and the β-lactamase superfamily. Mammals harbor a protein named LACTB that shares sequence similarity with bacterial penicillin-binding proteins and β-lactamases. Since eukaryotes lack the synthesis machinery for peptidoglycan, the physiological role of LACTB is intriguing. Recently, LACTB has been validated in vivo to be causative for obesity, suggesting that LACTB is implicated in metabolic processes. The aim of this study was to investigate the phylogeny, structure, biochemistry and cell biology of LACTB in order to elucidate its physiological function. Phylogenetic analysis revealed that LACTB has evolved from penicillin binding-proteins present in the bacterial periplasmic space. A structural model of LACTB indicates that LACTB shares characteristic features common to all penicillin-binding proteins and β-lactamases. Recombinat LACTB protein expressed in E. coli was recovered in significant quantities. Biochemical and cell biology studies showed that LACTB is a soluble protein localized in the mitochondrial intermembrane space. Further analysis showed that LACTB preprotein underwent proteolytic processing disclosing an N-terminal tetrapeptide motif also found in a set of cell death-inducing proteins. Electron microscopy structural studies revealed that LACTB can polymerize to form stable filaments with lengths ranging from twenty to several hundred nanometers. These data suggest that LACTB filaments define a distinct microdomain in the intermembrane space. A possible role of LACTB filaments is proposed in the intramitochondrial membrane organization and microcompartmentation. The implications of these findings offer novel insight into the evolution of mitochondria. Further studies of the LACTB function might provide a tool to treat mitochondria-related metabolic diseases.

Soil hydrological properties and conditions, site preparation, and the long-term performance of planted Scots pine (Pinus sylvestris L.) on upland forest sites in Finnish Lapland

Scots pine (Pinus sylvestris L.) and Norway spruce (Picea abies (L.) Karst.) forests dominate in Finnish Lapland. The need to study the effect of both soil factors and site preparation on the performance of planted Scots pine has increased due to the problems encountered in reforestation, especially on mesic and moist, formerly spruce-dominated sites. The present thesis examines soil hydrological properties and conditions, and effect of site preparation on them on 10 pine- and 10 spruce-dominated upland forest sites. Finally, the effects of both the site preparation and reforestation methods, and soil hydrology on the long-term performance of planted Scots pine are summarized. The results showed that pine and spruce sites differ significantly in their soil physical properties. Under field capacity or wetter soil moisture conditions, planted pines presumably suffer from excessive soil water and poor soil aeration on most of the originally spruce sites, but not on the pine sites. The results also suggested that site preparation affects the soil-water regime and thus prerequisites for forest growth over two decades after site preparation. High variation in the survival and mean height of planted pine was found. The study suggested that on spruce sites, pine survival is the lowest on sites that dry out slowly after rainfall events, and that height growth is the fastest on soils that reach favourable aeration conditions for root growth soon after saturation, and/or where the average air-filled porosity near field capacity is large enough for good root growth. Survival, but not mean height can be enhanced by employing intensive site preparation methods on spruce sites. On coarser-textured pine sites, site preparation methods don t affect survival, but methods affecting soil fertility, such as prescribed burning and ploughing, seem to enhance the height growth of planted Scots pines over several decades. The use of soil water content in situ as the sole criterion for sites suitable for pine reforestation was tested and found to be a relatively uncertain parameter. The thesis identified new potential soil variables, which should be tested using other data in the future.