Formal development of resilient distributed systems

Resilience is the property of a system to remain trustworthy despite changes. Changes of a different nature, whether due to failures of system components or varying operational conditions, significantly increase the complexity of system development. Therefore, advanced development technologies are required to build robust and flexible system architectures capable of adapting to such changes. Moreover, powerful quantitative techniques are needed to assess the impact of these changes on various system characteristics. Architectural flexibility is achieved by embedding into the system design the mechanisms for identifying changes and reacting on them. Hence a resilient system should have both advanced monitoring and error detection capabilities to recognise changes as well as sophisticated reconfiguration mechanisms to adapt to them. The aim of such reconfiguration is to ensure that the system stays operational, i.e., remains capable of achieving its goals. Design, verification and assessment of the system reconfiguration mechanisms is a challenging and error prone engineering task. In this thesis, we propose and validate a formal framework for development and assessment of resilient systems. Such a framework provides us with the means to specify and verify complex component interactions, model their cooperative behaviour in achieving system goals, and analyse the chosen reconfiguration strategies. Due to the variety of properties to be analysed, such a framework should have an integrated nature. To ensure the system functional correctness, it should rely on formal modelling and verification, while, to assess the impact of changes on such properties as performance and reliability, it should be combined with quantitative analysis. To ensure scalability of the proposed framework, we choose Event-B as the basis for reasoning about functional correctness. Event-B is a statebased formal approach that promotes the correct-by-construction development paradigm and formal verification by theorem proving. Event-B has a mature industrial-strength tool support { the Rodin platform. Proof-based verification as well as the reliance on abstraction and decomposition adopted in Event-B provides the designers with a powerful support for the development of complex systems. Moreover, the top-down system development by refinement allows the developers to explicitly express and verify critical system-level properties. Besides ensuring functional correctness, to achieve resilience we also need to analyse a number of non-functional characteristics, such as reliability and performance. Therefore, in this thesis we also demonstrate how formal development in Event-B can be combined with quantitative analysis. Namely, we experiment with integration of such techniques as probabilistic model checking in PRISM and discrete-event simulation in SimPy with formal development in Event-B. Such an integration allows us to assess how changes and di erent recon guration strategies a ect the overall system resilience. The approach proposed in this thesis is validated by a number of case studies from such areas as robotics, space, healthcare and cloud domain.

Future operational-tactical level warfare : challenges and opportunities for the defence of Finland

Finnish Defence Studies is published under the auspices of the National Defence College, and the contributions reflect the fields of research and teaching of the College. Finnish Defence Studies will occasionally feature documentation on Finnish Security Policy. Views expressed are those of the authors and do not necessarily imply endorsement by the National Defence College.

Individual Crimes or a Sociological Phenomenon: A Critical discourse analysis of the 2014 Royal Canadian Mounted Police National Operational Overview on missing and murdered Indigenous women in Canada

Pro gradu -tutkielma käsittelee Kanadan poliisivoimien, Royal Canadian Mounted Police (RCMP), vuoden 2014 operationaalista raporttia Kanadan kadonneista ja murhatuista alkuperäiskansojen naisista. Heitä katoaa ja murhataan Kanadassa suhteessa huomattavasti enemmän kuin muita naisia. Aihe on hyvin ajankohtainen sekä kriittinen ja siihen on paikallisten organisaatioiden lisäksi kiinnittänyt huomiota mm. Amnesty International ja Yhdistyneet Kansakunnat. Tilannetta pidetään jo ihmisoikeuskriisinä ja sen puolesta puhuminen voidaan nähdä osana laajempaa kansannousua alkuperäiskansojen oikeuksien puolesta. Kanadan hallitusta sekä poliisivoimia on syytetty välinpitämättömyydestä ja rasismista, poliiseja jopa väkivallasta alkuperäiskansojen naisia kohtaan. Kanadan hallitus ei myönnä ongelman olevan sosiologinen ilmiö, vaan pääministerin mukaan naisten katoamiset ja murhat ovat yksittäisiä rikoksia. Tilanteen taustalla on laajempi ongelma, joka juontaa juurensa kolonialismista, alkuperäiskansojen pakkokoulutuksesta ja heidän kulttuurinsa sekä identiteettinsä tuhoamisesta. Ennakkoluulot ja stereotypiat elävät yhä vahvana luoden heikon aseman alkuperäiskansojen edustajille ja tässä tapauksessa erityisesti naisille, joita myös usein syytetään omista ongelmistaan. Tutkielma selvittää, onko tämä operationaalinen raportti eriarvoisuutta, stereotypioita sekä ennakkoluuloja ylläpitävä ja tukeeko se näkemystä sosiologisesta ilmiöstä. Poliisivoimat ovat yhteiskunnassa vaikutusvaltaisessa asemassa ja voivat edesauttaa, jatkaa ja voimistaa syrjivää ajattelua, käytöstä ja viestintää. Vaikka he myös ajavat alkuperäiskansojen etuja, tulee heidän toimintaansa ja täten tätä kyseistä raporttia tarkastella kriittisesti. Tutkielma keskittyy kriittiseen diskurssianalyysiin (Fairclough 1995, Wodak & Meyer 2009). Raportin teksti ei ole avoimesti diskriminoivaa ja keskittyy tilastojen ja lukujen raportointiin sekä vertailuun, luoden samalla kuvan asianomaisista sekä tilanteesta yleisesti. Makroanalyysi (van Dijk 1977, 1980) mahdollistaa korkeamman tason ajatusten ja ideoiden esille tuonnin paljastaen ns. rivien välistä löytyvän viestinnän. Näistä makroanalyysin tuloksista etsitään erilaisia diskurssistrategioita (Reisigl & Wodak 2001), joiden avulla luodaan mm. kuva positiivisesta itsestä ja negatiivisesta toisesta. Näitä tuloksia tuetaan lyhyellä multimodaalisella analyysillä, joka keskittyy lähinnä raportin kahteen kuvaan (Kress & van Leeuwen 2006). Lopuksi tuloksista keskustellaan suhteessa yhteiskunnan valtasuhteisiin (Foucault 1976), rasismiin ja seksismiin. Analyysin perusteella raportti on selkeästi diskriminoiva. Se tuo esiin vanhoja stereotypioita ja ennakkoluuloja, esittää tilanteen alkuperäiskansojen sisäisenä ongelmana, jättää mainitsematta tilanteen taustat ja luo hyvin positiivisen kuvan poliisivoimista (RCMP). Tällä tavoin se ylläpitää yhteiskunnan epätasapainoisia valtasuhteita ja alkuperäiskansojen naisten heikompaa ja marginalisoitua asemaa. Raportti todistaa kuinka syvällä Kanadan yhteiskunnassa jopa institutionaalisella tasolla nämä ajatukset piilevät, sillä diskriminaatio ulottuu tapausten syistä niiden käsittelyyn ja raportointiin. Tilanne on huolestuttava ja voidaan nähdä sosiologisena ilmiönä. Poliisivoimien tulisi lisätä sisäistä koulutusta asian suhteen sekä hallituksen tutkia tätä ilmiönä ja paneutua sen selvittämiseen laaja-alaisesti ja läpinäkyvästi.

Individual Crimes or a Sociological Phenomenon: A Critical discourse analysis of the 2014 Royal Canadian Mounted Police National Operational Overview on missing and murdered Indigenous women in Canada

Pro gradu -tutkielma käsittelee Kanadan poliisivoimien, Royal Canadian Mounted Police (RCMP), vuoden 2014 operationaalista raporttia Kanadan kadonneista ja murhatuista alkuperäiskansojen naisista. Heitä katoaa ja murhataan Kanadassa suhteessa huomattavasti enemmän kuin muita naisia. Aihe on hyvin ajankohtainen sekä kriittinen ja siihen on paikallisten organisaatioiden lisäksi kiinnittänyt huomiota mm. Amnesty International ja Yhdistyneet Kansakunnat. Tilannetta pidetään jo ihmisoikeuskriisinä ja sen puolesta puhuminen voidaan nähdä osana laajempaa kansannousua alkuperäiskansojen oikeuksien puolesta. Kanadan hallitusta sekä poliisivoimia on syytetty välinpitämättömyydestä ja rasismista, poliiseja jopa väkivallasta alkuperäiskansojen naisia kohtaan. Kanadan hallitus ei myönnä ongelman olevan sosiologinen ilmiö, vaan pääministerin mukaan naisten katoamiset ja murhat ovat yksittäisiä rikoksia. Tilanteen taustalla on laajempi ongelma, joka juontaa juurensa kolonialismista, alkuperäiskansojen pakkokoulutuksesta ja heidän kulttuurinsa sekä identiteettinsä tuhoamisesta. Ennakkoluulot ja stereotypiat elävät yhä vahvana luoden heikon aseman alkuperäiskansojen edustajille ja tässä tapauksessa erityisesti naisille, joita myös usein syytetään omista ongelmistaan. Tutkielma selvittää, onko tämä operationaalinen raportti eriarvoisuutta, stereotypioita sekä ennakkoluuloja ylläpitävä ja tukeeko se näkemystä sosiologisesta ilmiöstä. Poliisivoimat ovat yhteiskunnassa vaikutusvaltaisessa asemassa ja voivat edesauttaa, jatkaa ja voimistaa syrjivää ajattelua, käytöstä ja viestintää. Vaikka he myös ajavat alkuperäiskansojen etuja, tulee heidän toimintaansa ja täten tätä kyseistä raporttia tarkastella kriittisesti. Tutkielma keskittyy kriittiseen diskurssianalyysiin (Fairclough 1995, Wodak & Meyer 2009). Raportin teksti ei ole avoimesti diskriminoivaa ja keskittyy tilastojen ja lukujen raportointiin sekä vertailuun, luoden samalla kuvan asianomaisista sekä tilanteesta yleisesti. Makroanalyysi (van Dijk 1977, 1980) mahdollistaa korkeamman tason ajatusten ja ideoiden esille tuonnin paljastaen ns. rivien välistä löytyvän viestinnän. Näistä makroanalyysin tuloksista etsitään erilaisia diskurssistrategioita (Reisigl & Wodak 2001), joiden avulla luodaan mm. kuva positiivisesta itsestä ja negatiivisesta toisesta. Näitä tuloksia tuetaan lyhyellä multimodaalisella analyysillä, joka keskittyy lähinnä raportin kahteen kuvaan (Kress & van Leeuwen 2006). Lopuksi tuloksista keskustellaan suhteessa yhteiskunnan valtasuhteisiin (Foucault 1976), rasismiin ja seksismiin. Analyysin perusteella raportti on selkeästi diskriminoiva. Se tuo esiin vanhoja stereotypioita ja ennakkoluuloja, esittää tilanteen alkuperäiskansojen sisäisenä ongelmana, jättää mainitsematta tilanteen taustat ja luo hyvin positiivisen kuvan poliisivoimista (RCMP). Tällä tavoin se ylläpitää yhteiskunnan epätasapainoisia valtasuhteita ja alkuperäiskansojen naisten heikompaa ja marginalisoitua asemaa. Raportti todistaa kuinka syvällä Kanadan yhteiskunnassa jopa institutionaalisella tasolla nämä ajatukset piilevät, sillä diskriminaatio ulottuu tapausten syistä niiden käsittelyyn ja raportointiin. Tilanne on huolestuttava ja voidaan nähdä sosiologisena ilmiönä. Poliisivoimien tulisi lisätä sisäistä koulutusta asian suhteen sekä hallituksen tutkia tätä ilmiönä ja paneutua sen selvittämiseen laaja-alaisesti ja läpinäkyvästi.

Public-private partnership investments in dry ports – Russian logistics markets and risks

The investments have always been considered as an essential backbone and so-called ‘locomotive’ for the competitive economies. However, in various countries, the state has been put under tight budget constraints for the investments in capital intensive projects. In response to this situation, the cooperation between public and private sector has grown based on public-private mechanism. The promotion of favorable arrangement for collaboration between public and private sectors for the provision of policies, services, and infrastructure in Russia can help to address the problems of dry ports development that neither municipalities nor the private sector can solve alone. Especially, the stimulation of public-private collaboration is significant under the exposure to externalities that affect the magnitude of the risks during all phases of project realization. In these circumstances, the risk in the projects also is becoming increasingly a part of joint research and risk management practice, which is viewed as a key approach, aiming to take active actions on existing global and specific factors of uncertainties. Meanwhile, a relatively little progress has been made on the inclusion of the resilience aspects into the planning process of a dry ports construction that would instruct the capacity planner, on how to mitigate the occurrence of disruptions that may lead to million dollars of losses due to the deviation of the future cash flows from the expected financial flows on the project. The current experience shows that the existing methodological base is developed fragmentary within separate steps of supply chain risk management (SCRM) processes: risk identification, risk evaluation, risk mitigation, risk monitoring and control phases. The lack of the systematic approach hinders the solution of the problem of risk management processes of dry port implementation. Therefore, management of various risks during the investments phases of dry port projects still presents a considerable challenge from the practical and theoretical points of view. In this regard, the given research became a logical continuation of fundamental research, existing in the financial models and theories (e.g., capital asset pricing model and real option theory), as well as provided a complementation for the portfolio theory. The goal of the current study is in the design of methods and models for the facilitation of dry port implementation through the mechanism of public-private partnership on the national market that implies the necessity to mitigate, first and foremost, the shortage of the investments and consequences of risks. The problem of the research was formulated on the ground of the identified contradictions. They rose as a continuation of the trade-off between the opportunities that the investors can gain from the development of terminal business in Russia (i.e. dry port implementation) and risks. As a rule, the higher the investment risk, the greater should be their expected return. However, investors have a different tolerance for the risks. That is why it would be advisable to find an optimum investment. In the given study, the optimum relates to the search for the efficient portfolio, which can provide satisfaction to the investor, depending on its degree of risk aversion. There are many theories and methods in finance, concerning investment choices. Nevertheless, the appropriateness and effectiveness of particular methods should be considered with the allowance of the specifics of the investment projects. For example, the investments in dry ports imply not only the lump sum of financial inflows, but also the long-term payback periods. As a result, capital intensity and longevity of their construction determine the necessity from investors to ensure the return on investment (profitability), along with the rapid return on investment (liquidity), without precluding the fact that the stochastic nature of the project environment is hardly described by the formula-based approach. The current theoretical base for the economic appraisals of the dry port projects more often perceives net present value (NPV) as a technique superior to other decision-making criteria. For example, the portfolio theory, which considers different risk preference of an investor and structures of utility, defines net present value as a better criterion of project appraisal than discounted payback period (DPP). Meanwhile, in business practice, the DPP is more popular. Knowing that the NPV is based on the assumptions of certainty of project life, it cannot be an accurate appraisal approach alone to determine whether or not the project should be accepted for the approval in the environment that is not without of uncertainties. In order to reflect the period or the project’s useful life that is exposed to risks due to changes in political, operational, and financial factors, the second capital budgeting criterion – discounted payback period is profoundly important, particularly for the Russian environment. Those statements represent contradictions that exist in the theory and practice of the applied science. Therefore, it would be desirable to relax the assumptions of portfolio theory and regard DPP as not fewer relevant appraisal approach for the assessment of the investment and risk measure. At the same time, the rationality of the use of both project performance criteria depends on the methods and models, with the help of which these appraisal approaches are calculated in feasibility studies. The deterministic methods cannot ensure the required precision of the results, while the stochastic models guarantee the sufficient level of the accuracy and reliability of the obtained results, providing that the risks are properly identified, evaluated, and mitigated. Otherwise, the project performance indicators may not be confirmed during the phase of project realization. For instance, the economic and political instability can result in the undoing of hard-earned gains, leading to the need for the attraction of the additional finances for the project. The sources of the alternative investments, as well as supportive mitigation strategies, can be studied during the initial phases of project development. During this period, the effectiveness of the investments undertakings can also be improved by the inclusion of the various investors, e.g. Russian Railways’ enterprises and other private companies in the dry port projects. However, the evaluation of the effectiveness of the participation of different investors in the project lack the methods and models that would permit doing the particular feasibility study, foreseeing the quantitative characteristics of risks and their mitigation strategies, which can meet the tolerance of the investors to the risks. For this reason, the research proposes a combination of Monte Carlo method, discounted cash flow technique, the theory of real options, and portfolio theory via a system dynamics simulation approach. The use of this methodology allows for comprehensive risk management process of dry port development to cover all aspects of risk identification, risk evaluation, risk mitigation, risk monitoring, and control phases. A designed system dynamics model can be recommended for the decision-makers on the dry port projects that are financed via a public-private partnership. It permits investors to make a decision appraisal based on random variables of net present value and discounted payback period, depending on different risks factors, e.g. revenue risks, land acquisition risks, traffic volume risks, construction hazards, and political risks. In this case, the statistical mean is used for the explication of the expected value of the DPP and NPV; the standard deviation is proposed as a characteristic of risks, while the elasticity coefficient is applied for rating of risks. Additionally, the risk of failure of project investments and guaranteed recoupment of capital investment can be considered with the help of the model. On the whole, the application of these modern methods of simulation creates preconditions for the controlling of the process of dry port development, i.e. making managerial changes and identifying the most stable parameters that contribute to the optimal alternative scenarios of the project realization in the uncertain environment. System dynamics model allows analyzing the interactions in the most complex mechanism of risk management process of the dry ports development and making proposals for the improvement of the effectiveness of the investments via an estimation of different risk management strategies. For the comparison and ranking of these alternatives in their order of preference to the investor, the proposed indicators of the efficiency of the investments, concerning the NPV, DPP, and coefficient of variation, can be used. Thus, rational investors, who averse to taking increased risks unless they are compensated by the commensurate increase in the expected utility of a risky prospect of dry port development, can be guided by the deduced marginal utility of investments. It is computed on the ground of the results from the system dynamics model. In conclusion, the outlined theoretical and practical implications for the management of risks, which are the key characteristics of public-private partnerships, can help analysts and planning managers in budget decision-making, substantially alleviating the effect from various risks and avoiding unnecessary cost overruns in dry port projects.

Effect of Material Recycling on the Feasibility of Solid Recovered Fuel Fired Power Plant

This master’s thesis examines the effects of increased material recycling on different waste-to-energy concepts. With background study and a developed techno-economic computational method the feasibility of chosen scenarios with different combinations of mechanical treatment and waste firing technologies can be evaluated. The background study covers the waste scene of Finland, and potential market areas Poland and France. Calculated cases concentrate on municipal solid waste treatment in the Finnish operational environment. The chosen methodology to approach the objectives is techno-economic feasibility assessment. It combines calculation methods of literature and practical engineering to define the material and energy balances in chosen scenarios. The calculation results together with other operational and financial data can be concluded to net present values compared between the scenarios. For the comparison, four scenarios, most vital and alternative between each other, are established. The baseline scenario is grate firing of source separated mixed municipal solid waste. Second scenario is fluidized bed combustion of solid recovered fuel produced in mechanical treatment process with metal separation. Third scenario combines a biomaterial separation process to the solid recovered fuels preparation and in the last scenario plastics are separated in addition to the previous operations. The results indicated that the mechanical treatment scenarios still need to overcome some problems to become feasible. Problems are related to profitability, residue disposal and technical reliability. Many uncertainties are also related to the data gathered over waste characteristics, technical performance and markets. With legislative support and development of further processing technologies and markets of the recycled materials the scenarios with biomaterial and plastic separation may operate feasibly in the future.

RELIABILITY AND SOCIAL KNOWLEDGERELEVANT RESPONSIBILITY

Knowledge seems to need the admixture of de facto reliability and epistemic responsibility. But philosophers have had a hard time in attempting to combine them in order to achieve a satisfactory account of knowledge. In this paper I attempt to find a solution by capitalizing on the real and ubiquitous human phenomenon that is the social dispersal of epistemic labour through time. More precisely, the central objective of the paper is to deliver a novel and plausible social account of knowledge-relevant responsibility and to consider the merits of the proposed combination of reliability and responsibility with respect to certain cases of unreflective epistemic subjects.

Reliability of a new measure of motoneuron excitability

Objectlve:--This study examined the intraclass reliability· of different measures of the excitability of the Hoffmann reflex, derived from stimulus-response curves. The slope of the regression line of the H-reflex stimulus-response curve advocated by Funase et al. (1994) was also compared to the peak of the first derivative of the H-reflex stimulus-response curve (dHIdVmax), a new measure introduced in this investigation. A secondary purpose was to explore the possibility of mood as a covariate when measuring excitability of the H-reflex arc. Methods: The H-reflex amplitude at a stimulus intensity corresponding to 5% of the maximum M-wave (Mmax) is an established measure that was used as an additional basis of comparison. The H-reflex was elicited in the soleus for 24 subjects (12 males and 12 females) on five separate days. Vibration was applied to the Achilles tendon prior to stimulation to test the sensitivity of the measures on test day four. The means of five evoked potentials at each gradually increasing intensity, from below H-reflex threshold to above Mmax, were used to create both the H-reflex and M-wave stimulus response curves for each subject across test days. The mood of the subjects was assessed using the Subjective Exercise Experience Scale (SEES) prior to the stimulation protocol each day. Results: There was a modest decrease in all H-reflex measures from the first to third test day, but it was non-significant (P's>0.05). All measures of the H-reflex exhibited a profound reduction following vibration on test day four, and then returned to baseline levels on test day five (P's<0.05). The intraclass correlation coefficient (ICC) for H-reflex amplitude at 5% of Mmax was 0.85. The ICC for the slope of the regression line was 0.79 while it was 0.89 for dH/dVmax. Maximum M-wave amplitude had an ICC of 0.96 attesting to careful methodological controls. The SEES subscales of fatigue and psychological well-being remained unchanged IV across the five days. The psychological distress subscale (PO.05). Conclusions: The peak of the first derivative of the H-reflex stimulus-response curve (dH/dVmax) was shown to have comparable reliability and sensitivity to other more established measures of excitability. Psychological distress and the amplitude of the H-reflex at 5% Mmax follow similar trends across days, however there was no significant correlation between the two measures. Significance: The proposed method appears to be a more robust measure ofH-reflex excitability than the other methods tested. As such it would be an advantageous method to apply in clinical and investigative settings. Additionally, the results suggest that the relationship between psychological distress and H-reflex amplitude should be investigated further.

The reliability of an isometric test based on constant perception of effort

To date there is no documented procedure to extrapolate findings of an isometric nature to a whole body performance setting. The purpose of this study was to quantify the reliability of perceived exertion to control neuromuscular output during an isometric contraction. 21 varsity athletes completed a maximal voluntary contraction and a 2 min constant force contraction at both the start and end of the study. Between pre and post testing all participants completed a 2 min constant perceived exertion contraction once a day for 4 days. Intra-class correlation coefficient (R=O.949) and standard error of measurement (SEM=5.12 Nm) concluded that the isometric contraction was reliable. Limits of agreement demonstrated only moderate initial reliability, yet with smaller limits towards the end of 4 training sessions. In conclusion, athlete's na"ive to a constant effort isometric contraction will produce reliable and acceptably stable results after 1 familiarization sessions has been completed.

Reliability of muscle fiber conduction velocity in the tibialis anterior

This document could not have been completed without the hard work of a number of individuals. First and foremost, my supervisor, Dr. David Gabriel deserves the utmost recognition for the immense effort and time spent guiding the production of this document through the various stages of completion. Also, aiding in the data collection, technical support, and general thought processing were Lab Technician Greig Inglis and fellow members of the Electromyographic Kinesiology Laboratory Jon Howard, Sean Lenhardt, Lara Robbins, and Corrine Davies-Schinkel. The input of Drs. Ted Clancy, Phil Sullivan and external examiner Dr. Anita Christie, all members ofthe assessment committee, was incredibly important and vital to the completion of this work. Their expertise provided a strong source of knowledge and went to ensure that this project was completed at exemplary level. There were a number of other individuals who were an immense help in getting this project off the ground and completed. The donation of their time and efforts was very generous and much needed in order to fulfill the requirements needed for completion of this study. Finally, I cannot exclude the contributions of my family throughout this project especially that of my parents whose support never wavers.

Major Sport Event Operational Planning Issues and Strategies: A Multi-Case Delphi Study

This study examined the operational planning, implementation and execution issues of major sport events, as well as the mitigation and management strategies used to address these issues, with the aim of determining best practices in sport event operational planning. The three Research Questions were: 1) What can previous major sport events provide to guide the operational management of future events? 2) What are the operational issues that arise in the planning and execution of a major sport event, how are they mitigated and what are the strategies used to deal with these issues? 3) What are the best practices for sport event operational planning and how can these practices aid future events? Data collection involved a modified Delphi technique that consisted of one round of in-depth interviews followed by two rounds of questionnaires. Both data collection and analysis were guided by an adaptation of the work of Parent, Rouillard & Leopkey (2011) with a focus on previously established issue and strategy categories. The results provided a list of Top 26 Prominent Issues and Top 17 Prominent Strategies with additional issue-strategy links that can be used to aid event managers producing future major sport events. The following issue categories emerged as having had the highest impact on previous major sport events that participants had managed: timing, funding and knowledge management. In addition, participants used strategies from the following categories most frequently: other, formalized agreements and communication.

Estimating the Tobit Model with Serial Correlation: an Operational Approach

Several Authors Have Discussed Recently the Limited Dependent Variable Regression Model with Serial Correlation Between Residuals. the Pseudo-Maximum Likelihood Estimators Obtained by Ignoring Serial Correlation Altogether, Have Been Shown to Be Consistent. We Present Alternative Pseudo-Maximum Likelihood Estimators Which Are Obtained by Ignoring Serial Correlation Only Selectively. Monte Carlo Experiments on a Model with First Order Serial Correlation Suggest That Our Alternative Estimators Have Substantially Lower Mean-Squared Errors in Medium Size and Small Samples, Especially When the Serial Correlation Coefficient Is High. the Same Experiments Also Suggest That the True Level of the Confidence Intervals Established with Our Estimators by Assuming Asymptotic Normality, Is Somewhat Lower Than the Intended Level. Although the Paper Focuses on Models with Only First Order Serial Correlation, the Generalization of the Proposed Approach to Serial Correlation of Higher Order Is Also Discussed Briefly.

The accuracy and reliability of plaster vs digital study models : a comparison of three different impression materials

Introduction: Le but de l’étude était d’examiner l’effet des matériaux à empreintes sur la précision et la fiabilité des modèles d’études numériques. Méthodes: Vingt-cinq paires de modèles en plâtre ont été choisies au hasard parmi les dossiers de la clinique d’orthodontie de l’Université de Montréal. Une empreinte en alginate (Kromopan 100), une empreinte en substitut d’alginate (Alginot), et une empreinte en PVS (Aquasil) ont été prises de chaque arcade pour tous les patients. Les empreintes ont été envoyées chez Orthobyte pour la coulée des modèles en plâtre et la numérisation des modèles numériques. Les analyses de Bolton 6 et 12, leurs mesures constituantes, le surplomb vertical (overbite), le surplomb horizontal (overjet) et la longueur d’arcade ont été utilisés pour comparaisons. Résultats : La corrélation entre mesures répétées était de bonne à excellente pour les modèles en plâtre et pour les modèles numériques. La tendance voulait que les mesures répétées sur les modèles en plâtre furent plus fiables. Il existait des différences statistiquement significatives pour l’analyse de Bolton 12, pour la longueur d’arcade mandibulaire, et pour le chevauchement mandibulaire, ce pour tous les matériaux à empreintes. La tendance observée fut que les mesures sur les modèles en plâtre étaient plus petites pour l’analyse de Bolton 12 mais plus grandes pour la longueur d’arcade et pour le chevauchement mandibulaire. Malgré les différences statistiquement significatives trouvées, ces différences n’avaient aucune signification clinique. Conclusions : La précision et la fiabilité du logiciel pour l’analyse complète des modèles numériques sont cliniquement acceptables quand on les compare avec les résultats de l’analyse traditionnelle sur modèles en plâtre.

Reliability of a quantitative clinical posture assessment tool among persons with idiopathic scoliosis

Objective To determine overall, test–retest and inter-rater reliability of posture indices among persons with idiopathic scoliosis. Design A reliability study using two raters and two test sessions. Setting Tertiary care paediatric centre. Participants Seventy participants aged between 10 and 20 years with different types of idiopathic scoliosis (Cobb angle 15 to 60°) were recruited from the scoliosis clinic. Main outcome measures Based on the XY co-ordinates of natural reference points (e.g. eyes) as well as markers placed on several anatomical landmarks, 32 angular and linear posture indices taken from digital photographs in the standing position were calculated from a specially developed software program. Generalisability theory served to estimate the reliability and standard error of measurement (SEM) for the overall, test–retest and inter-rater designs. Bland and Altman's method was also used to document agreement between sessions and raters. Results In the random design, dependability coefficients demonstrated a moderate level of reliability for six posture indices (ϕ = 0.51 to 0.72) and a good level of reliability for 26 posture indices out of 32 (ϕ ≥ 0.79). Error attributable to marker placement was negligible for most indices. Limits of agreement and SEM values were larger for shoulder protraction, trunk list, Q angle, cervical lordosis and scoliosis angles. The most reproducible indices were waist angles and knee valgus and varus. Conclusions Posture can be assessed in a global fashion from photographs in persons with idiopathic scoliosis. Despite the good reliability of marker placement, other studies are needed to minimise measurement errors in order to provide a suitable tool for monitoring change in posture over time.