Efficient estimation of blocking probabilities in non-stationary loss networks

This paper considers estimation of blocking probabilities in a nonstationary loss network. Invoking the so called MOL (Modified Offered Load) approximation, the problem is transformed into one requiring the solution of blocking probabilities in a sequence of stationary loss networks with time varying loads. To estimate the blocking probabilities Monte Carlo simulation is used and to increase the efficiency of the simulation, we develop a likelihood ratio method that enables samples drawn at a one time point to be used at later time points. This reduces the need to draw new samples every time independently as a new time point is considered, thus giving substantial savings in the computational effort of evaluating time dependent blocking probabilities. The accuracy of the method is analyzed by using Taylor series approximations of the variance indicating the direct dependence of the accuracy on the rate of change of the actual load. Finally, three practical applications of the method are provided along with numerical examples to demonstrate the efficiency of the method

Reduced formulation of a steady fluid-structure interaction problem with parametric coupling

We propose a two-fold approach to model reduction of fluid-structure interaction. The state equations for the fluid are solved with reduced basis methods. These are model reduction methods for parametric partial differential equations using well-chosen snapshot solutions in order to build a set of global basis functions. The other reduction is in terms of the geometric complexity of the moving fluid-structure interface. We use free-form deformations to parameterize the perturbation of the flow channel at rest configuration. As a computational example we consider a steady fluid-structure interaction problem: an incmpressible Stokes flow in a channel that has a flexible wall.Comment: 10 pages, 3 figure

Population ageing and fiscal sustainability in Finland: a stochastic analysis

This study analyses the fiscal sustainability of the Finnish public sector using stochastic projections to describe uncertain future demographic trends and asset yields. While current tax rates are unlikely to yield sufficient tax revenue to finance public expenditure with an ageing population, if developments are as expected, the problem will not be very large. However, there is a small, but not negligible, probability that taxes will need to be raised dramatically, perhaps by over 5 percentage points. Such outcomes, if realised, could destabilise the entire welfare state. The study also analyses three policy options aimed at improving sustainability. Longevity adjustment of pension benefits and introduction of an NDC pension system would reduce the expected problem and narrow the sustainability gap distribution. Under the third option, pension funds would invest more in equities and expect to get higher returns. This policy also limits the sustainability problem, but only under precondition that policymakers in the future can live with substantially larger variation in the value of the funds without adjusting tax rules or benefits.public finance; fiscal sustainability; uncertainty; stochastic simulations

The role of causation, effectuation and bricolage in new service development processes

This thesis examines the role of different types of entrepreneurial cognitive logics—namely causation, effectuation, and bricolage (CEB)—in new service development (NSD) processes within a new venture. To understand how entrepreneurial cognitive logics are used in the NSD process, I adopt a process research approach to study how service comes to be within a new venture in the healthcare industry. My research employs a range of methods between 2013 and 2017, including observation, interviews, and document analysis. Within current NSD models, means are not considered as part of processes which lead to new services; instead, the NSD process is assumed to start with a conscious intent to create a new service. My research has identified that NSD processes are often means driven and that the service developers ask themselves means-driven questions considered to represent effectuation logic. Hence, I shift the attention of NSD research from stable and resource-rich environments to dynamic and resource-constrained ones. As a result, I suggest that effectuation and bricolage are key perspectives in understanding NSD in uncertain and resource-scarce environments. In doing so, I challenge the predominantly causation-based formal and linear NSD stage model typically proposed in existing research. The findings show how CEB logics interplay and shift in a complex manner over time. Situational triggers, resource position, and unanticipated consequences, along with actor-dependent responses to internal and external influences, add to the complexity of how CEB logics interplay and shift over time. Furthermore, researching CEB logics on individual, team, and organisational levels reveals that the different logics may also cause conflict, thus leading not only to positive outcomes but also to frustration and tensions within the new venture

Laterality affects PRWE and QuickDASH scores after distal radius fractures : A prospective multicentre study

This study was executed to measure the effect of laterality on patient reported outcome measure (PROM) scores after distal radius fractures (DRFs). To investigate this, we sent Patient-Rated Wrist Evaluation (PRWE) and short version of Disabilities of the Arm, Shoulder and Hand (QuickDASH) questionnaires 6-8 weeks and 3-4 months after the fracture to 336 DRF patients, of which 119 were included to the study. The patients were divided into dominant and non-dominant side groups based on the side of the fracture, and the scores of the questionnaires were compared. At 6-8 weeks, the dominant group scored higher than non-dominant group in QuickDASH, which was in line with our hypothesis (p=0,04). A similar trend was noted in PRWE (p=0,12). When comparing only intra-articular fractures, a statistically significant difference between dominant and non-dominant groups at 6-8 weeks was noted in both PRWE (p=0,044) and QuickDASH (p=0,046). Similar trend was seen at 3-4 months even though our study was not designed to have sufficient power at this time point. Our results suggest that laterality should always be taken into account when studying DRFs by using PRWE or QuickDASH as an outcome measure due to its effect on the scores of these questionnaires.Värttinäluun alaosan murtumat ovat aikuisväestön yleisimpiä murtumia, joten niitä on myös tutkittu paljon. Vieläkään ei kuitenkaan tunneta kaikkia näiden murtumien hoitoon vaikuttavia muuttujia, joista yksi voisi olla potilaan kätisyys. Tämän tutkimuksen tarkoituksena oli tutkia kätisyyden vaikutusta potilaiden täyttämien oirekyselykaavakkeiden tuloksiin värttinäluun alaosan murtumien jälkeen. Tutkimuksessa lähetettiin kaksi oirekyselykaavaketta (Patient-Rated Wrist Evaluation, PRWE ja lyhyempi versio kyselykaavakkeesta Disabilities of the Arm, Shoulder and Hand, QuickDASH) 336 potilaalle, joilla oli todettuvärttinäluun alaosan murtuma. Kyselykaavakkeet lähetettiin potilaille 6-8 viikkoa ja 3-4 kuukautta vamman jälkeen. Lopulliseen tutkimukseen valikoitui 119 potilasta. Potilaat jaettiin kahteen ryhmään sen mukaan, oliko murtuma potilaan paremman vai huonomman käden puolella, minkä jälkeen kyselykaavakkeiden tuloksia verrattiin näiden ryhmien välillä. 6-8 viikon kuluttua vammasta paremman kätensä murtaneet potilaat saivat korkeampia tuloksia QuickDASH-kyselykaavakkeesta (p=0,04), mikä oli alkuperäisen hypoteesimme mukainen tulos. Myös PRWE-kyselykaavakkeen osalta havaittiin samansuuntainen tulos (p=0,12). Kun verrattiin pelkästään nivelensisäisiä murtumia keskenään, huomattiin tilastollisesti merkitsevä ero ryhmien välillä 6-8 kuluttua vammasta sekä PRWE- (p=0,044) että QuickDASH-kyselykaavakkeiden (p=0,046) tulosten välillä. Myös 3-4 kuukauden kuluttua vammasta saatiin samankaltaisia tuloksia, vaikka tutkimuksemme voima ja potilasmäärä oli laskettu riittäväksi 6-8 mittauspisteeseen, mutta ei 3-4 kuukauden mittauspisteeseen. Tulostemme perusteella potilaan kätisyys tulisi aina ottaa huomioon, kun tutkitaan värttinäluun alaosan murtumia PRWE- tai QuickDASH-kyselykaavakkeiden avulla, koska sillä on vaikutusta näiden kyselykaavakkeiden tuloksiin. Lisätutkimuksia tulisi tehdä vielä tämän vaikutuksen merkittävyyden määrittämiseksi

Model reduction and level set methods for shape optimization problems

In this work two topics related to mathematical shape optimization are considered. Topological optimization methods need not know the correct topology (number of connected components and possible holes) of the optimal shape beforehand. Shape optimization can be performed by a topological gradient descent algorithm. Computational applications of topological optimization and level set based shape optimization involve the optimal damping of vibrating structures and an inverse problem of reconstructing a shape based on noisy interferogram measurements. For parametric shape optimization with partial differential constraints the model reduction approach of reduced basis methods is considered. In the reduced basis method a basis of snapshot solutions is used to construct a problem-dependent approximation space that has much smaller dimension than the underlying finite element approximations. The state constraints for optimization are then replaced with their reduced basis approximation, leading to efficient shape optimization methods. Computational examples involve the optimal engineering design of airfoils in potential and thermal flow

Exhaustive mutagenesis of six secondary active-site residues in Escherichia coli chorismate mutase shows the importance of hydrophobic side chains and a helix N-capping position for stability and catalysis

Secondary active-site residues in enzymes, including hydrophobic amino acids, may contribute to catalysis through critical interactions that position the reacting molecule, organize hydrogen-bonding residues, and define the electrostatic environment of the active site. To ascertain the tolerance of an important model enzyme to mutation of active-site residues that do not directly hydrogen bond with the reacting molecule, all 19 possible amino acid substitutions were investigated in six positions of the engineered chorismate mutase domain of the Escherichia coli chorismate mutase-prephenate dehydratase. The six secondary active-site residues were selected to clarify results of a previous test of computational enzyme design procedures. Five of the positions encode hydrophobic side chains in the wild-type enzyme, and one forms a helix N-capping interaction as well as a salt bridge with a catalytically essential residue. Each mutant was evaluated for its ability to complement an auxotrophic chorismate mutase deletion strain. Kinetic parameters and thermal stabilities were measured for variants with in vivo activity. Altogether, we find that the enzyme tolerated 34% of the 114 possible substitutions, with a few mutations leading to increases in the catalytic efficiency of the enzyme. The results show the importance of secondary amino acid residues in determining enzymatic activity, and they point to strengths and weaknesses in current computational enzyme design procedures

Computationally designed variants of Escherichia coli chorismate mutase show altered catalytic activity

Computational protein design methods were used to predict five variants of monofunctional Escherichia coli chorismate mutase expected to maintain catalytic activity. The variants were tested experimentally and three active site mutants exhibited catalytic activity similar to or greater than the wild-type enzyme. One mutant, Ala32Ser, showed increased catalytic efficiency

Indikaatiot, löydökset, komplikaatiot sekä esilääkityksen ja anestesian käyttö HYKS Meilahden sairaalan endoskopiayksikön paksusuolen tähystyksissä vuonna 2010

Tutkimuksen tavoitteena oli selvittää Meilahden sairaalan endoskopiayksikössä vuonna 2010 tehtyjen paksusuolen tähystysten indikaatioita, löydöksiä, komplikaatioita, onnistumisastetta, tähystysten yhteydessä tehtyjä toimenpiteitä ja esilääkityksen käyttöä. Tutkimus tehtiin käymällä läpi kymmenen prosentin poiminta kaikista vuoden 2010 tähystyksistä sekä kaikki kyseisen vuoden anestesiassa tehdyt tähystystutkimukset. Tähystysten lausunnoista kerättiin tietoa edellä mainituista muuttujista. Tutkimuksessa keskeisimmiksi tähystysindikaatioiksi osoittautuivat tulehduksellisten suolistosairauksien ja leikatun syövän seuranta sekä adenoomapolyyppiseuranta. Erilaisten vatsaoireiden, kuten ripulin ja veriulosteen, osuus indikaationa oli pienempi. Esilääkityksen käyttö oli tutkimuksen mukaan varsin vähäistä, noin kahdessa kolmasosassa tähystyksistä ei käytetty mitään esilääkitystä. Yleisimpiä löydöksiä olivat tulehdukselliset suolistosairaudet, polyypit sekä normaalilöydökset. Kymmenen prosentin poiminnan tähystyksistä noin kolmeen prosenttiin liittyi jokin komplikaatio