Hintakartelli toistettuna pelinä: teoriasta pääkaupunkiseudun bensiinin vähittäismyyntimarkkinoille

Tutkielman tarkoituksena oli soveltaa toistetun pelin teoria- ja empiriapohjaa suomalaiseen tutkimusaineistoon. Kartellin toimintadynamiikka on mallinnettu peliteorian osa-alueen, toistetun pelin kentäksi. Toistetussa pelissä samaa, kerran pelattua peliä pelataan useita kierroksia. Äärettömästi toistetusta pelistä muodostuu toistetun pelin yleinen teoria (The Folk Theorem), jossa jokaisella pelaajalla on yksilöllisesti rationaalinen käytössykli. Toisen pelaajan kanssa tehty yhteistyö kasvattaa pelaajan käytössykliltä kertyvää kokonaishyötyä. Kartellitutkimuksessa ei voi ohittaa oikeustieteellistä näkökulmaa, joten sekin on tiivistetysti mukana esityksessä. Äänettömässä tai implisiittisessä kartellissa ( tacit collusion ) ei avoimen kartellin tavoin ole osapuolten välistä kommunikointia, mutta sen lopputulos on sama. Tästä syystä äänetön kartelli on yhdenmukaistettuna käytöksenä kielletty. Koska myös tunnusmerkit ovat osin samat, kartellitutkimus on saanut arvokasta mittausaineistoa paljastuneiden kartellien käytöksestä. Pelkkään hintatiedostoonkin perustuvalla tutkimuksella on vankka teoreettinen ja empiirinen pohja. Oikeuskirjallisuudessa ja käytännössä hintayhteneväisyyden on yhdessä muiden tunnusmerkkien kanssa katsottu olevan indisio kartellista. Bensiinin vähittäismyyntimarkkinat ovat rakenteellisesti otollinen kenttä toistetulle pelille. Tutkielman empiirisessä osuudessa kohteena olivat pääkaupunkiseudun bensiinin vähittäismyyntimarkkinat ja tiedosto sisälsi otoksia hinta-aikasarjoista ajalta 1.8.2004 - 30.6.2005 kaikkiaan 116:ltä jakeluasemalta Espoosta, Helsingistä ja Vantaalta. Tutkimusmenetelmänä oli toistettujen mittausten varianssianalyysi post hoc-vertailuin. Tilastollisesti merkitsevä hinnoitteluyhtenevyys lähellä sijaitsevien asemien kesken löytyi 47 asemalta, ja näin ollen näillä asemilla on yksi kartellin tunnusmerkeistä. Hinnoitteluyhtenevyyden omaavat asemat muodostivat liikenneyhteyksien mukaan jaetuilla kilpailualueillaan ryhmittymiä ja kaikkiaan tällaisia yhtenevästi hinnoittelevia ryhmittymiä oli 21. Näistä ryhmittymistä 9 oli ns. sekapareja eli osapuolina olivat kylmäasema ja liikenneasema. Useimmissa tapauksissa oli kyseessä alueensa kalleimmin hinnoitteleva kylmäasema. Tutkielman tärkeimmät lähteet: Abrantes-Metz, Rosa M. – Froeb, Luke M. – Geweke, John F. – Taylor, Cristopher T. (2005): A Variance screen for collusion. Working paper no. 275, Bureau of economics, Federal Trade Commission, Washington DC 20580. Dutta, Prajit K. (1999): Strategies and Games, Theory and Practice. The MIT Press, Cambridge, Massachusetts, London, England. Harrington, Joseph E. (2004): Detecting cartels. Working paper. John Hopkins University. Ivaldi, Marc – Jullien, Bruno – Rey, Patric – Seabright, Paul – Tirole, Jean (2003): The Economics of Tacit Collusion. EU:n komission kilpailun pääosaston julkaisu. Phlips, Louis (1996): On the detection of collusion and predation. European Economic Review 40 (1996), 495–510.

The management of large mammals in relation to male strategies and conflict with people

Many large mammals such as elephant, rhino and tiger often come into conflict with people by destroying agricultural crops and even killing people, thus providing a deterrent to conservation efforts. The males of these polygynous species have a greater variance in reproductive success than females, leading to selection pressures favouring a ‘high risk-high gain’ strategy for promoting reproductive success. This brings them into greater conflict with people. For instance, adult male elephants are far more prone than a member of a female-led family herd to raid agricultural crops and to kill people. In polygynous species, the removal of a certain proportion of ‘surplus’ adult males is not likely to affect the fertility and growth rate of the population. Hence, this could be a management tool which would effectively reduce animal-human conflict, and at the same time maintain the viability of the population. Selective removal of males would result in a skewed sex ratio. This would reduce the ‘effective population size’ (as opposed to the total population or census number), increase the rate of genetic drift and, in small populations, lead to inbreeding depression. Plans for managing destructive mammals through the culling of males will have to ensure that the appropriate minimum size in the populations is being maintained.

Hostility: A prospective study of the genetic and environmental background and associations with cardiovascular risk

Hostility is a multidimensional construct having wide effects on society. In its different forms, hostility is related to a large array of social and health problems, such as criminality, substance abuse, depression, and cardiovascular risks. Identifying and tackling early-life factors that contribute to hostility may have public health significance. Although the variance in hostility is estimated to be 18-50 percent heritable, there are significant gaps in knowledge regarding the molecular genetics of hostility. It is known that a cold and unsupportive home atmosphere in childhood predicts a child s later hostility. However, the long-term effects of care-giving quality on hostility in adulthood and the role of genes in this association are unclear. The present dissertation is part of the ongoing population-based prospective Young Finns study, which commenced in 1980 with 3596 3-18-year-old boys and girls who were followed for 27 years. The specific aims of the dissertation were first to study the antecedents of hostility by looking at 1) the genetic background, 2) the early environmental predictors, and 3) the gene environment interplay behind hostility. As a second aim, the thesis endeavored to examine 4) the association between hostility and cardiovascular risks, and 5) the moderating effect of demographic factors, such as gender and socioeconomic status, on this association. The study found potential gene polymorphisms from chromosomes 7, 14, 17, and 22 suggestively associated with hostility. Of early environmental influences, breastfeeding and early care-giving were found to predict hostility in adulthood. In addition, a serotonin receptor 2A polymorphism rs6313 moderated the effect of early care-giving on later hostile attitudes. Furthermore, hostility was shown to predict cardiovascular risks, such as metabolic syndrome and inflammation. Finally, parental socioeconomic status was found to moderate the association between anger and early atherosclerosis. The new genetic and early environmental antecedents of hostility identified in this research may help in understanding the development of hostility and its health risks, and in planning appropriate prevention. The significance of early influences on this development is stressed. Although the markers studied are individual- and family-related factors, these may be influenced at the societal level by giving accurate information to all individuals concerned and by improving the societal circumstances.

Sedimentary zooplankton remains as indicators of lake ecological quality and trophic structure

To protect and restore lake ecosystems under threats posed by the increasing human population, information on their ecological quality is needed. Lake sediments provide a data rich archive that allows identification of various biological components present prior to anthropogenic alterations as well as a constant record of changes. By providing a longer dimension of time than any ongoing monitoring programme, palaeolimnological methods can help in understanding natural variability and long-term ecological changes in lakes. As zooplankton have a central role in the lake food web, their remains can potentially provide versatile information on past trophic structure. However, various taphonomic processes operating in the lakes still raise questions concerning how subfossil assemblages reflect living communities. This thesis work aimed at improving the use of sedimentary zooplankton remains in the reconstruction of past zooplankton communities and the trophic structure in lakes. To quantify interspecific differences in the accumulation of remains, the subfossils of nine pelagic zooplankton taxa in annually laminated sediments were compared with monitoring results for live zooplankton in Lake Vesijärvi. This lake has a known history of eutrophication and recovery, which resulted from reduced external loading and effective fishing of plankti-benthivorous fish. The response of zooplankton assemblages to these known changes was resolved using annually laminated sediments. The generality of the responses observed in Lake Vesijärvi were further tested with a set of 31 lakes in Southern Finland, relating subfossils in surface sediments to contemporary water quality and fish density, as well as to lake morphometry. The results demonstrated differential preservation and retention of cladoceran species in the sediment. Daphnia, Diaphanosoma and Ceriodaphnia were clearly underrepresented in the sediment samples in comparison to well-preserved Bosmina species, Chydorus, Limnosida and Leptodora. For well-preserved species, the annual net accumulation rate was similar to or above the expected values, reflecting effective sediment focusing and accumulation in the deepest part of the lake. The decreased fish density and improved water quality led to subtle changes in zooplankton community composition. The abundance of Diaphanosoma and Limnosida increased after the reduction in fish density, while Ceriodaphnia and rotifers decreased. The most sensitive indicator of fish density was the mean size of Daphnia ephippia and Bosmina (E.) crassicornis ephippia and carapaces. The concentration of plant-associated species increased, reflecting expanding littoral vegetation along with increasing transparency. Several of the patterns observed in Lake Vesijärvi could also be found within the set of 31 lakes. According to this thesis work, the most useful cladoceran-based indices for nutrient status and planktivorous fish density in Finnish lakes were the relative abundances of certain pelagic taxa, and the mean size of Bosmina spp. carapaces, especially those of Bosmina (E.) cf. coregoni. The abundance of plant-associated species reflected the potential area for aquatic plants. Lake morphometry and sediment organic content, however, explained a relatively high proportion of the variance in the species data, and more studies are needed to quantify lake-specific differences in the accumulation and preservation of remains. Commonly occurring multicollinearity between environmental variables obstructs the cladoceran-based reconstruction of single environmental variables. As taphonomic factors and several direct and indirect structuring forces in lake ecosystems simultaneously affect zooplankton, the subfossil assemblages should be studied in a holistic way before making final conclusions about the trophic structure and the change in lake ecological quality.

The Commercial Structure of Pedestrian Streets and Shopping Districts - Three Cases from Finland

Kävelykadut ovat tunnustettu tapa elävöittää keskusta-alueiden kauppaa. Aluksi moni kauppias epäilee kävelykadun tuomia muutoksia, mutta kokemus osoittaa, että kävelykadut ovat olleet menestyksekkäitä ja nostavat siellä olevien yritysten myyntiä. Jotkut yritykset eivät kuitenkin hyödy kävelykaduista, kun taas toiset hyötyvät paljon kun katu muuttuu kävelykaduksi. Tämä pro gradu -tutkielma tutkii kävelykatujen kaupallista rakennetta, jotta saataisiin selville minkätyyppiset yritykset löytyvät kävelykadulta. Tuloksia verrataan sen kaupallisen keskusvyöhykkeen kaupalliseen rakenteeseen missä kävelykatu sijaitsee. Näin saadaan selville erot kaupallisessa rakenteessa. Pro gradu tutkii myös miten tavallisia ketjuyritykset ovat kävelykaduilla ja kaupallisissa keskusvyöhykkeissä. Tutkimusaineisto koottiin kaupallisen inventoinnin avulla, joka suoritettiin kolmessa suomalaisessa kaupungissa: Tammisaaressa, Keravalla ja Porissa. Saatu aineisto luokiteltiin ja tulokset piirrettiin kartalle. Perustilastollisia menetelmiä käytettiin tulosten analysoimisessa. Tulokset eriteltiin kävelykadun, kauppakeskusten ja muiden paikkojen osalta ja luokiteltiin yleisluokkiin vähittäiskauppa, ravintola ja muu palvelu. Tulokset näyttävät, että on olemassa selkeitä eroja kun vertaa kävelykatuja ja kaupallisia keskusvyöhykkeitä. Kävelykaduilla on paljon enemmän vähittäiskauppoja, etenkin muotikauppoja, kuin muilla kaduilla. Kauppakeskuksilla on samantapainen kaupallinen rakenne kuin kävelykaduilla kun taas muilla kaduilla esiintyy vähemmän vähittäiskauppoja ja enemmän palveluyrityksiä. Ravintolat ovat melkein yhtä tavallisia koko kaupallisessa keskusvyöhykkeessä. Ketjuyritysten osalta tulokset ovat epäselviä. On olemassa osviittaa siitä, että ne ovat tavallisempia kävelykaduilla, etenkin suurissa kaupungeissa. Saatua tulosta ei ole kuitenkin tarpeeksi, jotta varmaa tietoa olisi saatu. Viimeisten 10–15 vuoden ajan Suomen kävelykadut ovat muuttuneet enemmän ravintolavaltaisiksi muiden palveluiden kustannuksella. Vähittäiskauppojen määrä on pysynyt vakaana. Suomalaiset kävelykadut eroavat kaupalliselta rakenteeltaan pohjoismaisista kävelykaduista, joilla on enemmän vähittäiskauppoja ja vähemmän palveluyrityksiä. Tapauskohtaisissa tuloksissa esiintyy paljon eroavaisuuksia. Paikalliset tekijät ovat usein voimakkaampia kuin yleiset teoriat kauppojen sijainnista kävelykaduilla. Yleisesti ottaen tulokset tukevat teoreettista viitekehystä. Tulokset antavat tarkempaa tietoa kävelykatujen ja kaupallisten keskusvyöhykkeiden kaupallisesta rakenteesta ja siitä, mitkä tekijät tähän vaikuttaa.

Parametric instability of stochastic columns

Columns which have stochastically distributed Young's modulus and mass density and are subjected to deterministic periodic axial loadings are considered. The general case of a column supported on a Winkler elastic foundation of random stiffness and also on discrete elastic supports which are also random is considered. Material property fluctuations are modeled as independent one-dimensional univariate homogeneous real random fields in space. In addition to autocorrelation functions or their equivalent power spectral density functions, the input random fields are characterized by scale of fluctuations or variance functions for their second order properties. The foundation stiffness coefficient and the stiffnesses of discrete elastic supports are treated to constitute independent random variables. The system equations of boundary frequencies are obtained using Bolotin's method for deterministic systems. Stochastic FEM is used to obtain the discrete system with random as well as periodic coefficients. Statistical properties of boundary frequencies are derived in terms of input parameter statistics. A complete covariance structure is obtained. The equations developed are illustrated using a numerical example employing a practical correlation structure.

Päiväkodin varhaiskasvatussuunnitelma ja johtajuus : Kolmen kunnan päiväkodinjohtajien käsityksiä päiväkodin varhaiskasvatussuunnitelmasta

The research goal is to describe curriculas and leadership in day-care centers. The day-care centers needed to write their own curriculas, when Centre for Research and Development of Welfare and Health published The National Curriculum Guidelines on Early Childhood Education and Care in Finland (ECEC) in 2003. The study tries to review day-care center managers views of day-care centers plans for early childhood education and care in three municipals. The research data was collected in the begining of 2008. In previous researches it was found out that co-operation and employees knowledge of education in day-care centers will define the reality (Nivala). Furthermore sosial reality will be based on discussions (Berger JA Luckmann). The subject was approached by one-way analysis of variance. Views of the day-care center managers was compared to the written plans for early childhood education, it s effect on day-care center s early childhood education and evaluation. Besides day-care center managers views were compared to early childhood education. Day care center manager s (N=40) answers were collected to a questionnaire, where there were mainly structured and some open end questions. Data was analysed with PASW Statistics 17 program. The research results showed that the day-care center managers views of the prosess of writing the plans for early childhood education in the day-care centers varied from each other. In addition there were differences in views how the plan of day-care center s early childhood education effected daily in their early childhood education. Furthermore the results showed that there were differenties in evaluating day-care center s education. Whereas the views of early childhood education were not different between the day-care managers in the three municipals.

Nestedness pattern in stream diatom assemblages of central Western Ghats

Community diversity and the population abundance of a particular group of species are controlled by immediate environment, inter-and intra-species interactions, landscape conditions, historical events and evolutionary processes. Nestedness is a measure of order in an ecological system, referring to the order in which the number of species is related to area or other factors. In this study we have studied the nestedness pattern in stream diatom assemblages in 24 stream sites of central Western Ghats, and report 98 taxa from the streams of central Western Ghats region. The communities show highly significant nested pattern. The Mantel test of matrix revealed a strong relationship between species assemblages and environmental conditions at the sites. A significant relationship between species assemblage and environmental condition was observed. Principal component analysis (PCA) indicated that environmental conditions differed markedly across the sampling sites, with the first three components explaining 78% of variance. Species composition of diatoms is significantly correlated with environmental distance across geographical extent. The current pattern suggests that micro-environment at regional levels influences the species composition of epilithic diatoms in streams. The nestedness shown by the diatom community was highly significant, even though it had a high proportion of idiosyncratic species, characterized with high numbers of cosmopolitan species, whereas the nested species were dominated by endemic species. PCA identifies ionic parameters and nutrients as the major features which determine the characteristics of the sampling sites. Hence the local water quality parameters are the major factors in deciding the diatom species assemblages.

Data compression by linear prediction for storage and transmission of EEG signals

The EEG time series has been subjected to various formalisms of analysis to extract meaningful information regarding the underlying neural events. In this paper the linear prediction (LP) method has been used for analysis and presentation of spectral array data for the better visualisation of background EEG activity. It has also been used for signal generation, efficient data storage and transmission of EEG. The LP method is compared with the standard Fourier method of compressed spectral array (CSA) of the multichannel EEG data. The autocorrelation autoregressive (AR) technique is used for obtaining the LP coefficients with a model order of 15. While the Fourier method reduces the data only by half, the LP method just requires the storage of signal variance and LP coefficients. The signal generated using white Gaussian noise as the input to the LP filter has a high correlation coefficient of 0.97 with that of original signal, thus making LP as a useful tool for storage and transmission of EEG. The biological significance of Fourier method and the LP method in respect to the microstructure of neuronal events in the generation of EEG is discussed.

Performability of automated manufacturing systems with centralized material handling

We present a framework for performance evaluation of manufacturing systems subject to failure and repair. In particular, we determine the mean and variance of accumulated production over a specified time frame and show the usefulness of these results in system design and in evaluating operational policies for manufacturing systems. We extend this analysis for lead time as well. A detailed performability study is carried out for the generic model of a manufacturing system with centralized material handling. Several numerical results are presented, and the relevance of performability analysis in resolving system design issues is highlighted. Specific problems addressed include computing the distribution of total production over a shift period, determining the shift length necessary to deliver a given production target with a desired probability, and obtaining the distribution of Manufacturing Lead Time, all in the face of potential subsystem failures.

Monte-Carlo estimation of time-dependent statistical characteristics of random dynamical systems

The problem of estimating the time-dependent statistical characteristics of a random dynamical system is studied under two different settings. In the first, the system dynamics is governed by a differential equation parameterized by a random parameter, while in the second, this is governed by a differential equation with an underlying parameter sequence characterized by a continuous time Markov chain. We propose, for the first time in the literature, stochastic approximation algorithms for estimating various time-dependent process characteristics of the system. In particular, we provide efficient estimators for quantities such as the mean, variance and distribution of the process at any given time as well as the joint distribution and the autocorrelation coefficient at different times. A novel aspect of our approach is that we assume that information on the parameter model (i.e., its distribution in the first case and transition probabilities of the Markov chain in the second) is not available in either case. This is unlike most other work in the literature that assumes availability of such information. Also, most of the prior work in the literature is geared towards analyzing the steady-state system behavior of the random dynamical system while our focus is on analyzing the time-dependent statistical characteristics which are in general difficult to obtain. We prove the almost sure convergence of our stochastic approximation scheme in each case to the true value of the quantity being estimated. We provide a general class of strongly consistent estimators for the aforementioned statistical quantities with regular sample average estimators being a specific instance of these. We also present an application of the proposed scheme on a widely used model in population biology. Numerical experiments in this framework show that the time-dependent process characteristics as obtained using our algorithm in each case exhibit excellent agreement with exact results. (C) 2010 Elsevier Inc. All rights reserved.

Long term monitering of vegetation in a tropical deciduous forest in Mudumalai,southern India

As part of an international network of large plots to study tropical vegetation dynamics on a long-term basis, a 50-hectare permanent plot was set up during 1988-89 in the deciduous forests of Mudumalai, southern India. Within this plot 25,929 living woody plants (71 species) above 1 cm DBH (diameter at breast height) were identified, measured, tagged and mapped. Species abundances corresponded to the characteristic log-normal distribution. The four most abundant species (Kydia calycina, Lagerstroemia microcarpa, Terminalia crenulata and Helicteres isora) constituted nearly 56% of total stems, while seven species were represented by only one individual each in the plot. Variance/mean ratios of density showed most species to have clumped distributions. The population declined overall by 14% during the first two years, largely due to elephant and fire-mediated damage to Kydia calycina and Helicteres isora. In this article we discuss the need for large plots to study vegetation dynamics.

Climate change and agricultrue-An Indian perspective

In this paper, we examine the major predictions made so far regarding the nature of climate change and its impacts on our region in the light of the known errors of the set of models and the observations over this century. The major predictions of the climate models about the impact of increased concentration of greenhouse gases ave at variance with the observations over the Indian region during the last century characterized by such increases and global warming. It is important to note that as far as the Indian region is concerned, the impact of year-to-year variation of the monsoon will continue to be dominant over longer period changes even in the presence of global warming. Recent studies have also brought out the uncertainties in the yields simulated by crop models. It is suggested that a deeper understanding of the links between climate and agricultural productivity is essential for generating reliable predictions of impact of climate change. Such an insight is also required for identifying cropping patterns and management practices which are tailored for sustained maximum yield in the face of the vagaries of the monsoon.

Genetic search: Analysis using fitness moments

Genetic Algorithms are efficient and robust search methods that are being employed in a plethora of applications with extremely large search spaces. The directed search mechanism employed in Genetic Algorithms performs a simultaneous and balanced, exploration of new regions in the search space and exploitation of already discovered regions.This paper introduces the notion of fitness moments for analyzing the working of Genetic Algorithms (GAs). We show that the fitness moments in any generation may be predicted from those of the initial population. Since a knowledge of the fitness moments allows us to estimate the fitness distribution of strings, this approach provides for a method of characterizing the dynamics of GAs. In particular the average fitness and fitness variance of the population in any generation may be predicted. We introduce the technique of fitness-based disruption of solutions for improving the performance of GAs. Using fitness moments, we demonstrate the advantages of using fitness-based disruption. We also present experimental results comparing the performance of a standard GA and GAs (CDGA and AGA) that incorporate the principle of fitness-based disruption. The experimental evidence clearly demonstrates the power of fitness based disruption.

Critical earthquake input power spectral density function models for engineering structures

The problem of determining optimal power spectral density models for earthquake excitation which satisfy constraints on total average power, zero crossing rate and which produce the highest response variance in a given linear system is considered. The solution to this problem is obtained using linear programming methods. The resulting solutions are shown to display a highly deterministic structure and, therefore, fail to capture the stochastic nature of the input. A modification to the definition of critical excitation is proposed which takes into account the entropy rate as a measure of uncertainty in the earthquake loads. The resulting problem is solved using calculus of variations and also within linear programming framework. Illustrative examples on specifying seismic inputs for a nuclear power plant and a tall earth dam are considered and the resulting solutions are shown to be realistic.