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  • Julkunen, Asta-Maija (1985)
  • Grönqvist, Inkeri (1961)
  • Holmberg, Robert (Helsingin yliopisto, 2006)
    Ett sätt att förbättra resultat i informationssökning är frågeutvidgning. Vid frågeutvidgning utökas användarens ursprungliga fråga med termer som berör samma ämne. Frågor som har stort likhetsvärde med ett dokument kan tänkas beskriva dokumentet väl och kan därför fungera som en källa för goda utvidgningstermer. Om tidigare frågor finns lagrade kan termer som hittas med hjälp av dessa användas som kandidater för frågeutvidgningstermer. I avhandlingen presenteras och jämförs tre metoder för användning av tidigare frågor vid frågeutvidgning. För att evaluera metodernas effektivitet, jämförs de med hjälp av sökmaskinen Lucene och en liten samling dokument som berör cancerforskning. Som jämförelseresultat används de omodifierade frågorna och en enkel pseudorelevansåterkopplingsmetod som inte använder sig av tidigare frågor. Ingen av frågeutvidgningsmetoderna klarade sig speciellt bra, vilket beror på att dokumentsamlingen och testfrågorna utgör en svår omgivning för denna typ av metoder.
  • Liljeström, Anna (2010)
    För att driva ett lantbruksföretag framgångsrikt har tillgången till aktuell information stor betydelse. Det är viktigt att det finns bra informationskällor som kan utnyttjas då lantbrukarna t.ex. planerar att göra investeringar på gården som kanske kräver extern finansiering. Olika företag inom finansbranschen bör känna till vilken sorts information som lantbrukarna är i behov av samt vilka olika källor som företagarna använder för att skaffa information om olika finansieringsmöjligheter. Målsättningen med denna undersökning är att studera lantbruksföretagarnas användning av informationskällot. Problemfrågorna är: Vilka informationskällot använder lantbrukarna mest som hjälp för sitt yrkesutövande och inverkar bakgrundsfaktorer på användningen av informationskällor då man gör beslut? Vilken sorts information anser sig lantbrukarna behöva mest då de är i behov av extern finansiering? Forskningsmaterialet består av gårdar i Östra Nyland, Nyland, Åboland och Österbotten. Materialet samlades in via en enkätundersökning som utfördes våren 2009. Enkäten skickades ut åt 500 jordbrukare som var under 65 år. På enkäten svarade 165 jordbrukare dvs svarsprocenten var 33 %. Lantbruksföretagarna använder flere olika informationskällot är bara en för att klara av sin verksamhet på gården. De mest använda informationskällorna är tidningarna Landsbygdens Folk och Maaseudun Tulevaisuus samt övriga tidskrifter, lokaltidningar och kontakt med andra odlare. Internet används också ofta eller mycket ofta av närmare 56 % av lantbruksföretagarna vid yrkesutövande men har mycket mindre betydelse då man är mitt i en beslutsprocess. Internet används oftare av mera yngre personer. Över 80 % av lantbrukarna bedömer att de är i behov av finansieringsrådgivning inom närmaste framtid. I huvudsak vill lantbrukarna ha rådgivning om vanliga banklån men man vill även ha hjälp med investeringsstöd, räntestödslån och frågor kring generationsväxling. Undersökningens resultat visar också att bakgrundsfaktorer såsom ålder, utbildning och företagsstorlek styr valet av vilka informationskällor som lantbruksföretagarna använder sig mest av då de gör beslut på sina gårdar.
  • Knaster, Peter (Helsingin yliopisto, 2015)
    Chronic pain is a long-lasting burdensome condition. Comorbid psychological symptoms are common in chronic pain patients and they tend to worsen the treatment outcome. The aim of this cross-sectional study was to assess the prevalence of psychiatric comorbidity in chronic pain patients and to assess the associations between chronic pain, anxiety, anger, and depression. The study participants in the study were one hundred consecutive chronic pain patients referred to the Meilahti Pain Clinic of Helsinki University Hospital. The subjects were interviewed with the Structured Clinical Interview for DSM-IV for Axis I disorders (SCID-I). In addition self-report questionnaires were used in the assessment. Most (75%) patients had at least one lifetime mental disorder. The prevalence of major depressive disorder (MDD) was 37% and of a specific anxiety disorder 25% over the past 12 months. The psychiatric comorbidity was associated with increased pain intensity, measured by Visual Analogue Scale (VAS). The majority (77%) of the anxiety disorders had their onset before the onset of pain, whereas only 37% of the mood disorders preceded pain onset. The Harm Avoidance (HA) scale of the Temperament and Character Inventory (TCI) of Cloninger was associated with pain-related anxiety measured with Pain Anxiety Symptom Scale-20. The pain intensity influenced the strength of the association between the Harm Avoidance HA4 subscale and pain-related anxiety. Higher pain intensity was associated with stronger association between the variables. Likewise, pain intensity influenced the association between anger management and depression. A tendency to inhibit angry feelings was associated the somatic and physical symptoms of depression, measured by a two-factor model of the Beck Depression Inventory (BDI). The association was stronger in patients with higher pain intensity. Chronic pain patients with current MDD scored higher in both the somatic and cognitive-emotional subscales of the BDI compared with those without MDD. However, the somatic-physical-related items were more strongly associated with the diagnosis of MDD. Psychiatric disorders are common in chronic pain patients. Because of their influence on the chronic pain treatment and outcome, their thorough assessment is important. The linking mechanisms between chronic pain and the psychiatric disorders and symptoms are complicated and there is an overlap between the constructs. Clear boundaries between pain, anxiety and depression can be difficult to draw, which can be a reflection of the common background mechanisms such as common neural circuits and neurotransmitters.
  • Manninen, Kaisa (Helsingfors universitet, 2013)
    Anxiety disorders are a group of psychiatric disorders characterized by excessive fear and anxiety that disrupts normal life. They are very common, having an estimated life-time prevalence of 16.6 %, and they start often at an early age. Anxiety disorders have a clear genetic component, but the onset is also largely affected by the environment. Although several brain regions and neurotransmitter systems have been shown to take part in the regulation of anxiety, the exact pathophysiological mechanisms behind anxiety disorders are largely unknown. Mouse models are a good tool when studying the genetic component behind anxiety disorders. Different behavioral tests measuring the anxiety-like behavior of mice exist, and these tests can be used to model certain aspects of pathological anxiety. Individual gene effects on anxiety can be studied by using transgenic mouse models, which was done in this study, where a knockout mouse model lacking the functional version of glutathione reductase (Gsr) was used to study the effect of Gsr in anxiety. Because of the reduced viability of the homozygotic knockout mice, our study was done using heterozygotic knockout mice, which have 64 % of normal glutathione reductase activity. Glutathione is one of the most important endogenous antioxidants, which protects cells from oxidative stress by getting oxidized by reactive oxygen species. Glutathione reductase takes part in this process by transforming glutathione back to its functional reduced form. Gsr expression in amygdala and cingulate cortex has been previously shown to correlate with anxiety-like behavior in mice such that mice with upregulated Gsr expression were more anxious. This and other results obtained from mice and human studies suggest that oxidative stress may be involved in the pathogenesis of anxiety. In this study we wanted to investigate, whether the heterozygous Gsr knockout mice have lower anxiety-like behavior than the wild-type mice and whether there is more oxidative damage present in the brain of heterozygous Gsr knockout mice compared to the wild-type mice. To assess the first question, we set up and validated two behavioral tests (novelty-induced hypophagia and marble burying) and tested the Gsr mice using these tests. To assess the second question, we used nitrotyrosine as a marker for oxidative damage and measured the amount of this marker from brain tissue samples of Gsr mice by a nitrotyrosine immunoblotting assay. We discovered that both our novelty-induced hypophagia and marble burying test settings were able to detect some behavioral differences between inbred mouse strains, but were not optimal in distinguishing highly anxious strains from less anxious strains. When testing the Gsr mice, no behavioral difference between the heterozygous knockout and wild-type mice was observed, but a significant difference in the behavior between sexes was detected. We obtained preliminary results showing that the nitrotyrosine levels are slightly increased in the cortex of male heterozygous Gsr knockout mice. Whether this is the case also in other brain regions and in female mice still needs to be tested. These results and previous results obtained by our group suggest that heterozygous Gsr knockout mice do not have a striking anxiety phenotype under baseline conditions, but might have slightly reduced anxiety-like behavior and slightly increased brain oxidative stress status when compared to the wild-type mice.
  • Kangasharju, Jaakko (Helsingin yliopisto, 2006)
    In recent years, XML has been accepted as the format of messages for several applications. Prominent examples include SOAP for Web services, XMPP for instant messaging, and RSS and Atom for content syndication. This XML usage is understandable, as the format itself is a well-accepted standard for structured data, and it has excellent support for many popular programming languages, so inventing an application-specific format no longer seems worth the effort. Simultaneously with this XML's rise to prominence there has been an upsurge in the number and capabilities of various mobile devices. These devices are connected through various wireless technologies to larger networks, and a goal of current research is to integrate them seamlessly into these networks. These two developments seem to be at odds with each other. XML as a fully text-based format takes up more processing power and network bandwidth than binary formats would, whereas the battery-powered nature of mobile devices dictates that energy, both in processing and transmitting, be utilized efficiently. This thesis presents the work we have performed to reconcile these two worlds. We present a message transfer service that we have developed to address what we have identified as the three key issues: XML processing at the application level, a more efficient XML serialization format, and the protocol used to transfer messages. Our presentation includes both a high-level architectural view of the whole message transfer service, as well as detailed descriptions of the three new components. These components consist of an API, and an associated data model, for XML processing designed for messaging applications, a binary serialization format for the data model of the API, and a message transfer protocol providing two-way messaging capability with support for client mobility. We also present relevant performance measurements for the service and its components. As a result of this work, we do not consider XML to be inherently incompatible with mobile devices. As the fixed networking world moves toward XML for interoperable data representation, so should the wireless world also do to provide a better-integrated networking infrastructure. However, the problems that XML adoption has touch all of the higher layers of application programming, so instead of concentrating simply on the serialization format we conclude that improvements need to be made in an integrated fashion in all of these layers.
  • Somero, Marika Katariina (2014)
    Globalisation has reconfigured the territoriality and sovereignty, which has traditionally been associated with states. Economic actors, such as transnational corporations, have become powerful actors within the world’s economy and they are increasingly using their economic power to influence the actions of states. Transnational corporations business operations also directly affect the enjoyment of human rights by individuals, especially women. One such case which is considered in this thesis involves a textile manufacturing plant in Jordan called Classic, which produces clothes for some of America’s biggest retailers. The case involves allegations of sexual and physical abuse by the factory’s management against the factory’s female workers. As the case will demonstrate, transnational corporations are increasingly escaping liability for abuses which happen within their corporate structures and supply chains. Due to the power shift which has taken place in the last few decades, states are finding it increasingly more difficult to control the acts of non-state actors. Especially developing nations are often unable to regulate against the powerful transnational conglomerates, due to their economical dependence on the corporations presence in the country. Although international law is directly applicable to states, and most states sign up to international human rights conventions, international human rights law, as it currently stands, does not impose direct human rights obligations on corporations. Also, there are only limited circumstances when states can be held liable for the acts of non-state actors. As a result, the current human rights paradigm suffers from severe governance gap, which is rooted in the statist nature of international law. To address this shift in power dynamics, the thesis examines how the duty to protect individual’s human rights and the responsibility to respect human rights is distributed between states and transnational corporations. This thesis addresses this problem from two fronts: firstly, the thesis examines the current position of non-state actors within the international human rights structure and explores how states can be held liable for human rights violations which are committed by non-state actors, including transnational corporations. States duty to take positive steps to protect individuals within their jurisdictions are examined. International law has adopted a due “diligence” doctrine to address state responsibility in this context. To this end, the thesis reviews the development of the due diligence principle under international law and more specifically under women specific human rights instruments such as Convention on the Elimination of all Forms of Discrimination against Women. Jurisprudence of the European and Americas human rights courts as well as treaty bodies’ deliberations which interpret the due diligence concept are examined. Secondly, international law typically leaves states to regulate corporations via domestic law provisions and international law permits states to enforce international human rights norms against corporations under domestic law. Thus, states can hold corporations criminally and civilly liable for human rights violations under domestic laws, however, corporations do not currently have general obligations under international human rights law. To address this, the thesis examines recent attempts to establish direct human rights responsibilities on corporations within the international human rights system. The UN Draft Norms and John Ruggie’s “Protect, Respect and Remedy” Framework are explored in this context. Both frameworks highlight that corporations have specific duties to respect human rights and the “Protect, Respect and Remedy” Framework provides practical guidance for corporations in discharging this responsibility. The thesis concludes that recent decent developments domestically and internationally are increasingly contributing towards a paradigm shift within the international human rights law system, which is beginning to recognise that states as well as corporations have their distinctive roles to play in protecting human rights.
  • Granholm, Kaj (2002)
    Viimeaikaiset ehdotukset muuttaa Euroopan komissio Euroopan unionin hallitukseksi ovat kohdanneet monenlaisia reaktioita. Laajalle osalle tutkimuksesta on yhteistä se, että tämänsuuntaiset ehdotukset on kumottu vedoten yhtenäisen kansan kehittymättömyyteen, mikä estäisi hallituksen oikeutuksen. Tämä tutkimus ei pyri kiistämään aikaisempia väitteitä, vaan vain erottamaan hallituksen problematiikan laajemmasta kokonaisuudesta. Tutkimuksen aiheena on tulkita parlamentaarisen vastuunalaisuuden luonnetta Euroopan komissiossa. Tutkimus pyrkii ensiksi arvioimaan, miltä osin komission poliittinen vastuunalaisuus Euroopan parlamentille vastaa parlamentarismin periaatteita. Toiseksi, se hyödyntää vertailukohtana Kanadan hallituksen tilannetta ja asemaa liittovaltion toimeenpanevana elimenä. Vastuunalaisuuden katsotaan tässä tarkoittavan alttiutta parlamentaarisille kontrollimekanismeille. Tutkimuksen menetelmät ja olettamukset nojaavat institutionalistisen teorian atomistiseen lähestymistapaan sekä vertailevaan politiikan tutkimukseen. Tutkimus on normatiivinen, koska teoreettisena viitekehyksenä toimii parlamentarismin periaatteet. Vertailevan politiikan menetelmät tuodaan mukaan tutkimuksen varsinaisessa analyysissä rinnastettaessa Euroopan komission ja Kanadan hallituksen asema asianomaisiin edustuslaitoksiin nähden. Vertailevan tutkimuksen mahdollistamiseksi tutkimus tekee tiettyjä olettamuksia Euroopan unionin federalistisista olemuksista aikaisempien tutkimuksien perusteella sekä rinnastaa komission enemmistöhallitukseen. Teoreettisen viitekehyksen avulla esiin nostetut tulkinnat komission poliittisesta vastuunalaisuudesta rinnastetaan Kanada hallituksen asemasta tehtyihin tulkintoihin. Näin pyritään selvittämään, miten paljon paremmin hallituksen poliittisen vastuunalaisuuden voidaan olettaa toteutuvan täysin demokraattisessa federaatiossa. Tutkimuksen tuloksena havaittiin, että enemmistöhallituksen perinteen omaavassa federaatiossa parlamentaarinen vastuullisuus toteutuu heikommin. Tämä vahvisti tietyt aikaisemmat väitteet. Kuitenkin, myös parlamentaariset periaatteet keskenään toimivat osin toisiaan vastaan johtuen vastakkaisista voimista, joilla toisaalta pyritään mahdollistamaan parlamentin harjoittama kontrolli ja toisaalta takaamaan hallituksen työrauha. Näin ollen komission vastuullisuuden toteutuminen tietyiltä osin ei ole ratkaisevasti heikompi kuin esimerkkitapauksessa. Toisaalta tutkimuksen mahdollisuudet analysoida kaikkia vaikuttavia seikkoja oli puutteellinen, mistä johtuen kysymyksiä jäi avoimiksi lähinnä Euroopan parlamentin osalta.
  • Granholm, Kaj (2002)
    This study derives its motive from the recent proposals to transform the European Commission into the formal government of the European Union. It assumes political accountability to the parliament the executive to be a central element of any government, and therefore goes on to assess the degree to which the Commission is currently politically accountable to the European Parliament. Political accountability is regarded as susceptibility to parliamentary control mechanisms on the basis of political, rather than legal or financial matters. The study follows the atomistic approach to the institutionalist logic and a comparative method of political science, as it relates the Commission situation to that of the federal government of Canada. Comparativeness necessitates certain presumptions, which will be built on the nature of federalism in the EU, and consequently to the notion, that the European Commission can be regarded as a majority government. The central findings, on the one hand confirm previous arguments about the difficulty to fully realize parliamentary accountability in a federal setting. On the other hand, they add to the discussion an argument, by which certain parliamentarian principles also hinder the functioning of political accountability as they appear to outweight one another. Overall, however, albeit some outlying questions, this study finds that political accountability in Canada, a full parliamentary democracy, and the political accountability of the European Commission share certain common deficiencies.
  • Kallinen, Helena (2007)
    Eristetään Etelä-Afrikka –kampanja (EELAK) niminen kansalaisjärjestö toimi apartheidin vastaisen toiminnan kattojärjestönä Suomessa 1983-1992. Auto- ja Kuljetusalan Työntekijäliitto AKT oli EELAK:n merkittävin jäsenjärjestö, joka aloitti vuonna 1985 käytännössä Suomen ja Etelä-Afrikan välisen kaupan lopettaneen kuljetusboikotin. Tutkimuksessa selvitetään EELAK:n ja AKT:n roolijakoa boikotin ja siihen liittyneen painostustoiminnan aikana sekä EELAK:n merkitystä Suomen Etelä-Afrikkaan kohdistuneessa ulkopolitiikassa tapahtuneeseen muutokseen. Lisäksi tutkitaan EELAK:n ja apartheidin vastaisen toiminnan sopivuutta uuden politiikan teorioiden sekä liiketutkimuksen tarjoamaan viitekehykseen. Tutkimuksessa pääasiallisina lähteinä olivat Kansan Arkistossa sijaitsevat EELAK:n jälkeensä jättämät asiakirjat, lehtileikkeet, tiedotteet ja julkaistu kirjallisuus, Ulkoasiainministeriön Ulkopoliittisia lausuntoja ja asiakirjoja –julkaisut vuosilta 1985-1991 ja valtiopäivien pöytä- ja asiakirjat vuosilta 1985-1992. Näiden lisäksi tärkeimmät kirjallisuuslähteet olivat Tapio Bergholmin Kovaa peliä kuljetusalalla III, Timo-Erkki Heinon Politics on Paper -Finland’s South Africa Policy 1945-91, Pekka Peltolan ja Iina Soirin Finland and National Liberation in South Africa sekä Jari Luodon Ulkopolitiikka ja Ihmisoikeudet –Suomen kansainvälisen ihmisoikeuspolitiikan murroskausi 1985-1995. Tutkimus osoitti EELAK:n protestitoiminnan olleen tiivistä yhteistyötä AKT:n kanssa. EELAK levittyi laajalle yhteiskuntaan ja sillä oli kannattajia sekä kansaliaisjärjestöissä, ammattiyhdistysliitoissa, luterilaisessa kirkossa että eduskunnassa ja sen toiminta sisälsi sekä uuden politiikan että uusien liikkeiden muodot. EELAK ajoi samanaikaisesti esimerkiksi sekä Etelä-Afrikan vastaisten lakien säätämistä Suomen eduskuntaa ja hallitusta painostamalla että järjesti mielenosoituksia ja keräyksiä vapausliikkeiden ja apartheidin uhrien tukemiseksi. Tutkimuksen aikana selvisi, että uudet poliittisen vaikuttamisen muodot ja uusien liikkeiden vaikuttamisen muodot ovat lähes täysin yhteneväiset vaikka uudesta politiikasta ja uusista liikkeistä puhuttaessa tarkoitetaan täysin eri aikakausia. Tutkimuksen myötä esitetään, että oikeudenmukaisempaa olisi puhua vaihtoehtoisista vaikuttamisen muodoista, jotka kattaisivat alleen uuden politiikan ja uusien liikkeiden toimintarepertuaarin. EELAK:n voidaan esittää olevan yhteiskunnallinen liike, joka oli 1960-luvulla heränneen apartheidin vastaisen liikkeen toinen herääminen. Boikotoinnin ymmärtäminen sen laajan käsitteen mukaisesti kattaa alleen myös kuluttajaboikotoinnista eroavat boikotoinnin muodot ja samalla siihen voi ymmärtää liittyvän muitakin painostuskeinoja. AKT:n kuljetusboikotin lisäksi Etelä-Afrikan boikotin nimellä on hyväksyttävää puhua kaikesta Etelä-Afrikan eristystä ajavasta toiminnasta.
  • Uski, Jaana (2013)
    Tässä työssä esitellään Apollonioksen ongelma. Alkuperäinen Apollonioksen ongelma oli löytää euklidisessa tasossa ympyrä, joka sivuaa kolmea annettua ympyrää. Yleensä kuitenkin sallitaan ympyröiden degeneroituminen pisteeksi tai suoraksi (ympyrä, jonka säde on nolla tai "ääretön"). Tämän takia ongelma usein laajennetaan ongelmaksi löytää ympyrä, joka sivuaa kolmea kuviota, joista kukin voi olla piste, suora tai ympyrä. Ongelmassa on näin yhteensä kymmenen eri tapausta. Apollonios Pergalainen (n. 240-190 eaa) julkaisi ja ratkaisi ongelman teoksessaan Sivuamisista lukuunottamatta vaikeinta kolmen ympyrän tapausta. Ratkaisut eivät ole säilyneet, mutta ne on voitu rekonstruoida Pappos Aleksandrialaisen kuvausten perusteella. 1500-1600-luvulla monet matemaatikot yrittivät ratkaista Apollonioksen ongelman vaikeinta tapausta euklidisen geometrian hengessä harpilla ja viivottimella. Tässä työssä perehdytään yleisimpiin menetelmiin, joilla Apollonioksen ongelma saadaan ratkaistua. Erityisesti työssä perehdytään vaikeimpaan, kolmen ympyrän, tapaukseen. Tälle esitetään algebrallinen ratkaisumenetelmä sekä inversioon eli ympyräpeilaukseen ja hyperbeleihin perustuvat ratkaisumenetelmät. Lisäksi esitellään vielä Joseph Diaz Gergonnen keksimä konstruktio.
  • Viheriäranta, Anni (Helsingin yliopisto, 2014)
    Escaping apoptosis is an important, acquired capability of tumor cells and is considered a hallmark of cancer. Furthermore, tumor suppressors and apoptotic proteins function as natural barriers for excessive proliferation induced by oncogenes and can be often found as mutated or lost in cancer. Understanding how tumor cell specific apoptotic pathways are working, may guide development of future therapeutic strategies inducing apoptosis specifically in tumor cells. One of the highly overexpressed oncogene in cancers is Myc that is a global transcription factor regulating variety of cellular functions such as proliferation and apoptosis. One of the major aims in this study was to elucidate mechanisms for Myc-induced sensitization of cells to cell death. Herein, the results presented here provide evidence that Myc-induced apoptosis is strictly mitochondria-dependent. Furthermore, our findings expose new evidence for Bcl-2 family member mediated control of Myc-induced apoptosis showing that Myc expression results in activation of Bak. Interestingly, our data suggest a novel Bak activation step, where Myc induces Bak to undergo conformational change and expose its N-termini, however, without further homo-oligomerization or apoptosis. Hence, we open new ideas for the current Bak/Bax activation models suggested earlier. In addition, our data indicate that Myc expression results in phosphorylation and accumulations of mitochondrial p53 that is priming the mitochondria for death stimuli. Herein, these results indicate that cytoplasmic p53 has a crucial role in Myc-induced stress responses. The data presented here also suggest that BH3 mimetic drugs can sensitize tumor cells to Myc-apoptosis in vivo, which also highlights the role of Bcl-xL as a key controller of Myc-dependent apoptosis in epithelial tumors. Thereby, our results point new therapeutic possibilities that could be used in combination to treat breast cancer. Finally, in this study we found an interesting connection between the Myc-induced metabolic transformation and the apoptotic signaling of Myc. We suggest that Myc expression induces activation of metabolic pathways specific for cancer cell such as activating the glutaminolytic pathway and promoting a catabolic mode of metabolism through increasing fatty acid oxidation. Furthermore, our results indicate that Myc-induced decline in the ATP contents of the cell is leading to an activation of a cellular energy sensor AMPK. Consequently, AMPK is able to induce Bak activation and apoptotic sensitivity via phosphorylation and stabilization of p53. Importantly, our results bring new insight into oncogenic stress and apoptotic sensitivity by Myc highlighting the role of metabolism. All together, it will be future challenge to understand how that knowledge of coupled metabolic stress and apoptotic sensitivity can be used for therapeutic interventions in cancer.
  • Bandyopadhyay, Payel (2015)
    The way the users interact with Information Retrieval (IR) systems is an interesting topic of interest in the field of Human Computer Interaction (HCI) and IR. With the ever increasing information in the web, users are often lost in the vast information space. Navigating in the complex information space to find the required information, is often an abstruse task by users. One of the reasons is the difficulty in designing systems that would present the user with an optimal set of navigation options to support varying information needs. As a solution to the navigation problem, in this thesis we propose a method referred as interaction portfolio theory, based on Markowitz’s "Modern Portfolio theory", a theory of finance. It provides the users with N optimal interaction options in each iteration, by taking into account user’s goal expressed via interaction during the task, but also the risk related to a potentially suboptimal choice made by the user. In each iteration, the proposed method learns the relevant interaction options from user behaviour interactively and optimizes relevance and diversity to allow the user to accomplish the task in a shorter interaction sequence. This theory can be applied to any IR system to help users to retrieve the required information efficiently.