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The accurate replication of the mammalian genome is a complex and logistically challenging process. The entirety of the genome must undergo a single duplication with as little error as possible. This must occur in a coordinated fashion and over suitably short time scale so as to allow timely cellular division within a cell cycle that is typically around 24 hours in a human cell. A great wealth of knowledge already exists describing various aspects of the S phase, during which this replication of the genome occurs. This data has been gathered over a variety of model systems, ranging from inferences from the replicative mechanics of SV40 through to direct observations of replication in mammalian cells.In order integrate this data and determine the value of inferences from different data sources, quantitative models of the mammalian cell S phase are required. This study documents the development of several such models and the exploration of the influences that experimentally determined parameters and different mechanistic theories can have on the behaviour of a simulated S phase. Of particular exploratory interest were the modes of activating replication of replicon clusters, with the aim of simulating experimentally observed dynamics. Additionally, the study also aimed to investigate the variation of replication fork rates and the density of origins of replication, along with the relationship that occurs between the two during both replicational stress and during a normal S phase. Through an iterative series of models, relevant parameters and key theories are sequentially explored so as to better understand the S phase. Particularly influential parameters were identified and studied in detail, with experimental determination where necessary in order to more accurately inform the model system. Conclusions concerning the behaviour of the system and the potential impact of the results were drawn upon the completion of each level of modelling and experimental work.To conclude the study, a linear model simulating the genome of the MRC5 cell line was used to estimate the modes activation of DNA replication along chromosomes in order to recreate experimentally observed replication dynamics. Experimentally determined profiles of replication fork rates and the density of origin firing were also determined for the MRC5 cell line, and were used to populate the model with accurate and appropriate data. Using the model to simulate S phase through a variety of behavioural parameters, realistic S phase dynamics were found to occur through a combination of de novo activation of replicon clusters and a specific probability of neighbour activation by completed clusters. These derived mechanics, when performed on a system correctly parameterised with suitable data, can simulate experimentally observed phenomena. The development of the model highlighted the requirements of data fit for purpose, and the study also stresses the need for critical consideration of inferences made between different model systems.

Abstract Management of product development activities has become increasingly important, as cycle times of product development have shortened. Smaller product development projects are often conducted rapidly at companies based on customer or sales requests to answer the need for faster cycle times. However, this is often done without fully realizing the impact of the new projects on the larger project portfolio or organizational effectiveness. The main objective of this dissertation is to increase knowledge on the use of agile development methods in small, rapid product development projects, and on the implementation of a rapid product development model. The dissertation is formulated as a qualitative, inductive study based on the research results of four original publications and a summary combining the results. The results of the dissertation show that it is beneficial to separate a rapid product development process for certain types of customer- or sales-initiated projects. A new rapid development model with principles and guidelines is introduced to help organizations facilitate this separation. The implementation of the model can be supported with agile development practices, of which self-managing teams are studied in more detail. There is significant overlap between case companies’ perceived success factors for rapid development and self-management. The results imply that a functional rapid development model can be utilized as a strategic asset at companies. The results also provide empirical evidence that agile development practices can be utilized in product development. In addition to providing empirical evidence in scientific discussion about combining product development and agile software development practices, the results can be used to create better definitions of product development processes in general. / Tiivistelmä Tuotekehityksen johtamisesta ja hallinnasta on tullut entistä haastavampaa ja tärkeämpää, kun tuotekehitysprojektien läpimenoajat ovat lyhentyneet. Yritykset tekevät kasvamassa määrin lyhyitä tuotekehitysprojekteja asiakaspyyntöjen tai myynnin aloitteesta vastatakseen markkinoiden vaatimuksiin nopeasta kehityksestä. Tällaisten nopeiden tuotekehitysprojektien käynnistäminen ja toteutus tehdään usein ymmärtämättä yksittäisen projektin vaikutusta koko projektiportfolioon tai organisaation tehokkuuteen. Tämän väitöskirjan päätavoitteena on tutkia ohjelmistokehityksestä tunnettujen ketterien kehitysmenetelmien käyttöä nopeissa tuotekehitysprojekteissa ja uudenlaisen nopean tuotekehityksen mallin käyttöönotossa. Tutkimus on tehty laadullisena ja induktiivisena tutkimuksena perustuen neljään itsenäiseen tutkimusartikkeliin ja näiden tulokset kokoavaan kokoelmaosaan. Tutkimus osoittaa, että yrityksille on hyödyllistä erottaa erillinen prosessi tietyntyyppisille nopeille tuotekehitysprojekteille. Tutkimuksen tuloksena esitellään malli, joka tukee tätä erottamista periaatteiden ja ohjeiden avulla. Tätä mallia pystytään tukemaan ketterillä kehitysmenetelmillä, joihin liittyen on erityisesti tutkittu itseohjautuvia kehitystiimejä. Case-yritysten havainnoimilla nopean tuotekehityksen menestystekijöillä ja itseohjautuvien tiimien ominaisuuksilla on havaittavissa suurta päällekkäisyyttä. Tulokset osoittavat, että hyvin käytetty ja määritetty nopean tuotekehityksen malli voi olla strateginen kilpailuetu yrityksille. Tulokset lisäävät myös empiiristä tietoa ketterien menetelmien käytöstä tuotekehityksessä ja hyödyntävät siten ajankohtaista tieteellistä keskustelua. Tuloksia voidaan myös hyödyntää muiden tuotekehitysprosessien käyttötarkoituksen tarkempaan määrittämiseen.