983 resultados para man-made cyanobacterial crusts


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Laborationerna utgör i många skolor inom den grundläggande utbildningen en självklar del av kemiundervisningen. Laborationerna är vanligen formulerade som ”recept” och eleverna skall följa en given beskrivning då de genomför laborationen. Kravet på eget tänkande från elevernas sida kan härigenom bli litet. Laborationerna är därför utsatta för en hel del kritik på olika håll i världen, därför att de anses ineffektiva ur lärande-synvinkel. S.k. öppna laborationer är en annan typ av laboration som innebär att eleverna ställs inför ett problem eller en utmaning. Eleverna skall själva inom sin laborationsgrupp komma underfund med och planera hur de skall genomföra laborationen. Denna form av laborationer ställer andra krav på elevernas tänkande än traditionella ”kokbokslaborationer”. I denna studie har elever i en klass i årskurs 7 under sin första kemikurs arbetat med öppna laborationer. Laborationerna har av klassens lärare formulerats som utmaningar för eleverna. Eleverna har som ett hjälpverktyg under laborationen använt s.k. V-diagram. V-diagram utgör ett grafiskt verktyg som kan användas som en laborationsrapport. I V-diagrammet synliggörs de olika momenten som ingår i en laboration eller i en undersökning. Vilken är forskningsfrågan, hur planerar man att söka svar på sin fråga, vilka resultat har man kommit till och vilka slutsatser kan man dra? V-diagrammet innehåller också en teoretisk och begreppslig sida där laborationens teoretiska förankring synliggörs. Resultaten från undersökningen visar att arbetet med öppna laborationer i kombination med V-diagram hade positiv inverkan på elevernas uppfattning om sitt eget lärande. Eleverna upplevde att laborationerna krävde tänkande men att detta samtidigt ledde till förståelse. Eleverna hjälpte varandra att försöka förstå då de gemensamt skulle lösa problem. I diskussionen med sina kamrater och med läraren fick eleverna möjlighet att formulera sina egna uppfattningar och konfrontera dem mot andra uppfattningar. V-diagrammets struktur fungerade som vägledning då eleverna planerade sin laboration, men gav också en överblick över laborationer i efterhand då eleverna förberedde sig inför kursprovet, vilket för en del elever bidrog till deras förståelse. Grupperna var i allmänhet mycket fokuserade på uppgiften då de planerade en öppen laboration. Laborationerna hade alla en förankring i vardagen vilket gjorde att eleverna kunde göra kopplingar mellan sina egna erfarenheter och laborationen. Majoriteten av eleverna uppgav efter kemikursen att de upplevt den som intressant och laborationerna lyftes fram speciellt. De öppna laborationerna ställde stora krav på laborationsgrupperna och på elevernas samarbetsförmåga och gjorde laborationerna känsliga för grupprelaterade problem, genom att eleverna skulle klara av utmaningar gemensamt. För en elev med svag självuppfattning kan tillrättalagda laborationer med klara instruktioner kännas tryggare än en öppen laboration, där utmaningen är större. Samtidigt hade just utmaningarna, som var på en nivå som eleverna klarade av efter att ha tänkt och diskuterat med varandra, en positiv inverkan på självuppfattningen för ett flertal av eleverna. Att klara av utmaningar på rätt nivå kan inverka positivt på den egna själuppfattningen. De öppna laborationerna ställer krav på läraren att vara flexibel och kunna gå in i rollen av bl.a. handledare och coach. Samtidigt utgör lärare en representant för det naturvetenskapliga samfundet och har ansvar för att göra teori och begrepp tillgängliga för eleverna då de behöver dessa i sina undersökningar. För lärare kan de öppna laborationerna kännas problematiska, eftersom de själva sällan har erfarenheter av denna typ av laborationer från sin egen skoltid eller utbildning.

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Earlier research has shown that strong experiences related to music (SEM) can occur in very different contexts and take on many different forms. Experiences like these seem significant and have among other things reportedly had an affect on the individual's continuing relationship towards music, which makes them interesting from a pedagogical point of view. Formal teaching situations, though, are under-represented in studies where people have been asked to describe strong experiences that they have had in connection with music. The purpose of my thesis is to investigate what SEM may mean to pupils and teachers in lower secondary school (grades 7-9), and to inquire more deeply into the potential "space" for such experiences within school music education. On a comprehensive level my ambition is to deepen the understanding for SEM as a possible element in pedagogical situations. Three empirical perspectives are employed: pupil-, teacher- and curriculum perspectives. The pupil perspective involved an analysis of written accounts of 166 fifteen-year-olds, describing own strong experiences. The teacher perspective involved studying 28 music teachers' conceptions of the purpose of teaching music in school as well as their understanding about strong music experiences in school context. Further, the teachers' descriptions of SEM that they have had themselves were analysed. The curriculum perspective is reflected through a study of how music experience was represented in 24 local and 2 national curriculum texts for music. Grounded in a phenomenological-hermeneutical perspective the material have been analyzed both qualitatively and quantitatively. The result points towards the fact that the music education in school has the potential to become an arena for SEM and that this can happen in relation to a multitude of activities and genres and take on many different expressions. Only one pupil referred to a musical encounter in the classroom environment; all other experiences that occurred inside the frame of school activity had taken place in other arenas (the school hall, public concert halls, and so on). However, more than 98 % of the descriptions concerned musical encounters in leisure time contexts. The significance of SEM is further clarified by narrative constructions. SEM as a conception does not occur on the curriculum level; however the analyze revealed a number of interesting "openings" which are illustrated. Even though all teachers displayed a fundamentally positive attitude towards the idea of regarding SEM as a feature of formal musical learning, it became clear that many teachers never had approached this theme from a pedagogical point of view before. Still, they proved to have an evident "familiarity" towards the phenomenon based on their own experiences of receptive and performative musical encounter. The possible space for strong musical experiences within school music education is specified through a detailed illustration of six specific themes derived from the reasoning of the teachers. Furthermore, this is described through a mapping of the potential experiencing zone, constructed from the teachers descriptions of educational aims.

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The aim of this thesis is to gain new understanding of health based on the work Penseés (Thoughts) by Blaise Pascal. The research interest originates from the motive of the heart for the greatness of man in conjunction with his baseness. The study is hermeneutic and the purpose is to describe health formulated as new abductive theses based on the assumption that caring science and caring theology can be conjoined in the same ontology. The work Penseés is, in Gadamer’s sense, alive since the text is constantly being made use of and is in this occurence interpreted through the requirements made by caring science. Pascal’s arguments continue through the historically effected consciousness while the interpretation is confronted with the ontological model of health. In the initial horizon we find the understanding of the motion of health and the extension towards text materials which is undertaken by Pascal’s Penseés. to open up the perspective and be able to project the horizon of the text. In the encounter with the text, the core content will first be discussed in an interpretative part after which the understanding gained will be summarized into new abductive assumptions. On the basis of Gadamer’s emphasis on the applications of the interpretations, the merging of the horizons will identify health as something desired by man, what he is and what he wants to accomplish. The creation of health is the reason of the heart, and on the basis of what man wants to confide in, the rise of health will be established. The totality of greatness and baseness of man is achieved by the accomplishment of health. That man owns spiritual devotedness means health whereas unhealthy means that he is insecure of his character and leads a life with ill-considered amusements. When according to Pascal, man’s desires and thoughts are joined in the heart, a connecting relation will arise. Hence the spiritual edification that man will fail to secure if he puts too much of his confidence in transient reason is included, something that is insufficient when it comes to understand the meaning of health.

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The purpose of this thesis is to develop a theory model about some core concepts and phenomena within caritative ethics when patients' demands are existential. There are two research questions, (A) Which realities represent concepts such courage, responsibility, and sacrifice within the caritative ethics. (B) Which phenomena of ethical significance are made current and applicable when patients¿ demands are existential. This study takes as its point of departurecertain chosen theoretical perspectives that discuss some perspectives of the concepts of courage, responsibility, and sacrifice in terms of their significanceto the research questions A. This represents the study¿s theoretical data. The empirical data provide answers to the research question B. In the end, the thesis discusses synthesis of these two accesses of knowledge in order to formulate theses and create a theory model. Løgstrup's contribution and description of the ethical claim helps in understanding and interpreting the links between the substance of the caritative ethic and the concrete reality in the encounter with existential issues. This thesis is a study within the field of Caring Science. The nursing profession provides empirical data and reflects the study topic, by addressing issues of relevance to the application of the knowledge of Caring Sciencein light of the nursing profession's various daily challenges. This study proceeds from the basic assumption: "Caring relationships form the meaningful contextfor caring and derive from the ethos of love, responsibility, and sacrifice, i.e. a caritative ethics" (Eriksson 2001). This study attempts to explore and prove this statement in the light of theoretical and empirical data, in the light ofthe caring scientific perspective which is here linked particularly to the viewof man as a unity of body, mind, and soul, and to the ontological health model. Hermeneutics is the overall perspective for the interpretations proposed in this thesis. Through conversation and hermeneutic observations, I try to understandthe challenges of nursing performance in the encounter with existential issues. This constitutes the empirical data that was gathered on a ward treating cancerpatients. The discussion proceeds sequence by sequence, first by discussing theconditions of the caritative ethics when meeting the existential claims in the light of the concepts of courage, sacrifice, and responsibility. Then a thesis is formulated concerning the caritative ethics in the light of Caring Science. This is the foundation of the creation of the theory model. The resulting theses concern the chosen concepts and phenomena which promote caritative ethics when patients' claims are existential: Freedom is the hallmark of caritative ethics. Freedom is the basic category of caring. When attending to the patient's existential claims, it is of vital importance to secure human relationships as caring interpersonal communions, created by responsible persons who have shown courage and sacrifice. Courage and sacrifice constitute the ethos of caring communities (communions). Courage and sacrifice are then a part of the collective ethos of caring communities, because the patient is confirmed as the unity of body, mind, and soul.

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The home as ethos, an ethical dimension of human beings, is this study’s focus of interest. Can the home as ethos comprise motive and driving force for a human being? This dissertation has a mainly hermeneutic approach with a Caring Science interpretive horizon. Firstly, the purpose of this study is to develop the concept “home” through etymological and semantic analysis. The concept’s Caring Science content is also investigated. Secondly, the purpose of this study is to investigate, through the use of a history of ideas method, how the home as ethos is made visible and evident in public health nurses’ caring during the first half of the 20th century. Which motives compromise the driving force behind public health nurses’ caring? Which idea patterns are stressed? Material for the study’s concept determination consists of tymological dictionaries as well as Swedish language dictionaries published from 1850 – 2001. The results of the concept determination provide a preliminary idea-model, where dimensions such as ethos as a human being’s innermost room, human beings’ manner of being, and the metaphor “my home is my castle” are stressed. These results comprise the background of the history of ideas portion of the study. The study’s history of ideas investigation occurs through the evaluation and interpretation of historical sources focusing on the caring provided by public health nurses. Public health nurses comprise both the context and prevalent traditions during the time-period studied. The historical sources consist of three different types of sources, namely textbooks, archived material, and the professional nursing journals Epione and Sairaanhoitajatarlehti. The purpose is to rediscover fundamental idea-patterns through the thematic structuring of the patterns appearing in the historical sources. Three main idea-patterns and underlying themes are rediscovered: love- a fire which burns inside human beings; reverence for human beings and home; and the honor of responsibility. The emerging patterns are tightly interwoven and form a pattern. A new interpretation occurs, widening the study’s horizon and leading to the emergence of the theory-model’s contours. The study’s theory-model is formed from three different levels. Ethos as a human being’s innermost room- the spirit, encompasses a human being’s value base and the spirit that he/she is permeated with. Fundamental values are converted into an internal ethic, becoming visible in human beings’ manner of being- the manner of conduct. The metaphor “my home is my castle”- the tone, symbolizes the room where a human being’s abstract or concrete being lives. The spirit, the ethos, is expressed in a home’s culture and atmosphere, that is to say the tone of a home or how one lives in a room. Communion is a significant component in the creation of a culture and atmosphere. This study’s theory-model gives rise to a new perspective that can generate new patterns of action. The study’s theory-model results in a new historically-based view that create new patterns of action in care and Caring Science today.

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The objective of this dissertation is to improve the dynamic simulation of fluid power circuits. A fluid power circuit is a typical way to implement power transmission in mobile working machines, e.g. cranes, excavators etc. Dynamic simulation is an essential tool in developing controllability and energy-efficient solutions for mobile machines. Efficient dynamic simulation is the basic requirement for the real-time simulation. In the real-time simulation of fluid power circuits there exist numerical problems due to the software and methods used for modelling and integration. A simulation model of a fluid power circuit is typically created using differential and algebraic equations. Efficient numerical methods are required since differential equations must be solved in real time. Unfortunately, simulation software packages offer only a limited selection of numerical solvers. Numerical problems cause noise to the results, which in many cases leads the simulation run to fail. Mathematically the fluid power circuit models are stiff systems of ordinary differential equations. Numerical solution of the stiff systems can be improved by two alternative approaches. The first is to develop numerical solvers suitable for solving stiff systems. The second is to decrease the model stiffness itself by introducing models and algorithms that either decrease the highest eigenvalues or neglect them by introducing steady-state solutions of the stiff parts of the models. The thesis proposes novel methods using the latter approach. The study aims to develop practical methods usable in dynamic simulation of fluid power circuits using explicit fixed-step integration algorithms. In this thesis, twomechanisms whichmake the systemstiff are studied. These are the pressure drop approaching zero in the turbulent orifice model and the volume approaching zero in the equation of pressure build-up. These are the critical areas to which alternative methods for modelling and numerical simulation are proposed. Generally, in hydraulic power transmission systems the orifice flow is clearly in the turbulent area. The flow becomes laminar as the pressure drop over the orifice approaches zero only in rare situations. These are e.g. when a valve is closed, or an actuator is driven against an end stopper, or external force makes actuator to switch its direction during operation. This means that in terms of accuracy, the description of laminar flow is not necessary. But, unfortunately, when a purely turbulent description of the orifice is used, numerical problems occur when the pressure drop comes close to zero since the first derivative of flow with respect to the pressure drop approaches infinity when the pressure drop approaches zero. Furthermore, the second derivative becomes discontinuous, which causes numerical noise and an infinitely small integration step when a variable step integrator is used. A numerically efficient model for the orifice flow is proposed using a cubic spline function to describe the flow in the laminar and transition areas. Parameters for the cubic spline function are selected such that its first derivative is equal to the first derivative of the pure turbulent orifice flow model in the boundary condition. In the dynamic simulation of fluid power circuits, a tradeoff exists between accuracy and calculation speed. This investigation is made for the two-regime flow orifice model. Especially inside of many types of valves, as well as between them, there exist very small volumes. The integration of pressures in small fluid volumes causes numerical problems in fluid power circuit simulation. Particularly in realtime simulation, these numerical problems are a great weakness. The system stiffness approaches infinity as the fluid volume approaches zero. If fixed step explicit algorithms for solving ordinary differential equations (ODE) are used, the system stability would easily be lost when integrating pressures in small volumes. To solve the problem caused by small fluid volumes, a pseudo-dynamic solver is proposed. Instead of integration of the pressure in a small volume, the pressure is solved as a steady-state pressure created in a separate cascade loop by numerical integration. The hydraulic capacitance V/Be of the parts of the circuit whose pressures are solved by the pseudo-dynamic method should be orders of magnitude smaller than that of those partswhose pressures are integrated. The key advantage of this novel method is that the numerical problems caused by the small volumes are completely avoided. Also, the method is freely applicable regardless of the integration routine applied. The superiority of both above-mentioned methods is that they are suited for use together with the semi-empirical modelling method which necessarily does not require any geometrical data of the valves and actuators to be modelled. In this modelling method, most of the needed component information can be taken from the manufacturer’s nominal graphs. This thesis introduces the methods and shows several numerical examples to demonstrate how the proposed methods improve the dynamic simulation of various hydraulic circuits.

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The paper industry is constantly looking for new ideas for improving paper products while competition and raw material prices are increasing. Many paper products are pigment coated. Coating layer is the top layer of paper, thus by modifying coating pigment also the paper itself can be altered and value added to the final product. In this thesis, synthesis of new plastic and hybrid pigments and their performance in paper and paperboard coating is reported. Two types of plastic pigments were studied: core-shell latexes and solid beads of maleimide copolymers. Core-shell latexes with partially crosslinked hydrophilic polymer core of poly(n-butyl acrylate-co-methacrylic acid) and a hard hydrophobic polystyrene shell were prepared to improve the optical properties of coated paper. In addition, the effect of different crosslinkers was analyzed and the best overall performance was achieved by the use of ethylene glycol dimethacrylate (EGDMA). Furthermore, the possibility to modify core-shell latex was investigated by introducing a new polymerizable optical brightening agent, 1-[(4-vinylphenoxy)methyl]-4-(2-henylethylenyl)benzene which gave promising results. The prepared core-shell latex pigments performed smoothly also in pilot coating and printing trials. The results demonstrated that by optimizing polymer composition, the optical and surface properties of coated paper can be significantly enhanced. The optimal reaction conditions were established for thermal imidization of poly(styrene-co-maleimide) (SMI) and poly(octadecene-co-maleimide) (OMI) from respective maleic anhydride copolymer precursors and ammonia in a solvent free process. The obtained aqueous dispersions of nanoparticle copolymers exhibited glass transition temperatures (Tg) between 140-170ºC and particle sizes from 50-230 nm. Furthermore, the maleimide copolymers were evaluated in paperboard coating as additional pigments. The maleimide copolymer nanoparticles were partly imbedded into the porous coating structure and therefore the full potential of optical property enhancement for paperboard was not achieved by this method. The possibility to modify maleimide copolymers was also studied. Modifications were carried out via N-substitution by replacing part of the ammonia in the imidization reaction with amines, such as triacetonediamine (TAD), aspartic acid (ASP) and fluorinated amines (2,2,2- trifluoroethylamine, TFEA and 2,2,3,3,4,4,4-heptafluorobuthylamine, HFBA). The obtained functional nanoparticles varied in size between 50-217 nm and their Tg from 150-180ºC. During the coating process the produced plastic pigments exhibited good runnability. No significant improvements were achieved in light stability with TAD modified copolymers whereas nanoparticles modified with aspartic acid and those containing fluorinated groups showed the desired changes in surface properties of the coated paperboard. Finally, reports on preliminary studies with organic-inorganic hybrids are presented. The hybrids prepared by an in situ polymerization reaction consisted of 30 wt% poly(styrene- co-maleimide) (SMI) and high levels of 70 wt% inorganic components of kaolin and/or alumina trihydrate. Scanning Electron Microscopy (SEM) images and characterization by Fourier Transform Infrared Spcetroscopy (FTIR) and X-Ray Diffraction (XRD) revealed that the hybrids had conventional composite structure and inorganic components were covered with precipitated SMI nanoparticles attached to the surface via hydrogen bonding. In paper coating, the hybrids had a beneficial effect on increasing gloss levels.

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Nedbrytning av blågrönalgtoxiner med hälsobefrämjande mjölksyrebakterier Blomningar av cyanobakterier (blågrönalger) har blivit ett världsomfattande fenomen i eutrofierade vattenmiljöer. Cyanobakterier producerar toxiner, både levergifter och nervgifter, vilka utgör en hälsorisk för människan. Exponeringsrutter omfattar både dricksvatten och förorenade matvaror. Rening av dricksvatten från dessa toxiner är således av hög prioritet. Konventionella vatttenreningsprocesser är inte alltid tillräckligt effektiva mot cyanotoxiner. Därför behövs utveckling av nya effektiva biologiska metoder för vattenrening, vilka kunde komplettera de redan existerande metoderna. FM Sonja Nybom har i sin doktorsavhandling undersökt eliminering av cyanotoxiner från dricksvatten med hjälp av probioter. Probiotiska bakterier, såsom mjölksyrebakterier och bifidobakterier, finns i den naturliga tarmfloran och har även visats ha gynnsamma effekter för människans hälsa. I avhandlingen visades flera olika stammar av probiotiska mjölksyrebakterier och bifidobakterier effektivt eliminera cyanotoxiner, såsom levergiftiga microcystiner, från vatten. Elimineringen undersöktes under olika omständigheter och visades vara beroende av bland annat vattentemperatur, pH, celldensitet och närvaro av kolkälla (glukos) för bakterierna. Metaboliskt aktiva, levande bakterier krävdes för effektiv toxineliminering. En kombination av flera probiotstammar resulterade i effektivare nedbrytning av toxiner i jämförelse med enskilda bakteriestammar. Även reaktionstiden var av betydelse för effektiviteten; efter ett dygns inkubering åstadkoms nästan total nedbrytning. Sammanfattningsvis tyder resultaten på att metoder utnyttjande dessa hälsobefrämjande probiotiska bakterier kunde utvecklas till att användas vid rening av dricksvatten från cyanotoxiner samt användas som en personlig skyddsmekanism mot cyanotoxiner i mag-tarmkanalen.

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The main advantage of organic electronics over the more widespread inorganic counterparts lies not in the electrical performance, but rather in the solution processability that opens up for low-cost flexible electronics (e.g. displays, sensors and smart tags) fabricated by using printing techniques. Replacing the commonly used laboratory-scale fabrication techniques with mass-printing techniques is, however, truly challenging, especially when low-voltage operation is required. In this thesis it is, nevertheless, demonstrated that low-voltage organic transistors can be fully printed with a similar performance to that of transistors made by laboratory scale techniques. The use of an ion-modulated type of organic field effect transistor (OFET) not only enabled low-voltage operation and printability, but was also found to result in low sensitivity to the surface roughness of the substrate. This allows not only the use of low-cost plastic substrates, but even the use of paper as a substrate. However, while absorption into the porous paper surface is advantageous in a graphical printing process, by reducing the spreading and the coffee-stain effect and by improving the adhesion, it provides great challenges when applying thin electrically active layers. In spite of these difficulties we were able to demonstrate the first low-voltage OFET to be fabricated on paper. We have also shown that low-cost incandescent lamps can be used for sintering printed metal-nanoparticles, and that the process was especially suitable on paper and compatible with a roll-to-roll manufacturing process.

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Treatment, morbidity and mortality of patients with gallstone ileus depend on an accurate diagnosis made in time, and also on a more adequate therapeutic option.A detailed clinical evaluation is fundamental for such diagnosis. Complementary exams like a simple radiological study of the abdomen, high and low endoscopies, an ultrasonography, and a tomography can also be performed. The therapeutic options include the removal of the obstructive factor separately, the performance of a treatment in two separate stages, or the performance of a complete treatment (removal of the calculus, cholecystectomy, and the closing of the fistula).This study aims to present a case report of an elderly man of high surgical risk, presenting gallstone ileus. He was submitted to an isolated videoassisted enterolithotomy through a minilaparotomy. Taking into consideration the patient’s advanced age and the lack of evidence as to other biliary associated pathologies, the chosen treatment seemed to be a good alternative. The evolution was good, and after an 8 month follow-up the patient was found well and with no biliary symptoms whatsoever.

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A case of lower gastrointestinal bleeding due to metastatic malignant melanoma in a man, in which the final diagnosis was made only on surgery, is reported. The patient underwent a segmentary enterectomy with primary anastomosis and he was discharged on tenth postoperative day.

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Tämän tutkimuksen tavoitteena on selvittää kannattaako makrotaloudellisia muuttujia käyttää tunnuslukujen lisäksi yrityksen konkurssin ennustamisessa. Perinteiset konkurssinennustamismallit hyödyntävät pelkästään tilinpäätöksestä saatavia tunnuslukuja eivätkä huomioi yrityksen toimintaympäristöä ja sen muutoksia. Aiemmissa tutkimuksissa makrotaloudellisilla muuttujilla on pystytty parantamaan perinteisiä ennustamismalleja. Tutkimus toteutetaan luomalla kolme erilaista konkurssinennustamismallia logistista regressioanalyysiä hyödyntäen ja vertailemalla niiden paremmuutta. Tutkimustulokset osoittavat, että rakennusalan pk-yritysten konkursseja pystytään ennustamaan kolmen tunnusluvun mallilla. Taloudellisen ajanjakson, jolta yrityksen tiedot ovat peräisin, huomioiminen ei tuo malliin lisäarvoa eikä paranna ennustamiskykyä merkittävästi.