The Czech Republic's economic performance is measurable by some macroeconomic indicators which have made variable progress in recent years. Based on general economic conditions, economic development has impacted upon economic results of companies. Over time their progress is recorded by economic time series, which describe it. Through the agency of economic time series, economic development and mutual dependences among indicators can be researched. This problem can be solved by applying the methodology which helps describe and quantify relations among quantities. For the purpose of expression of a single time series, stochastic linear modelling is used, and for quantifying the strength of relation among time series, regression analyses and Granger causality testing are used.

Emergency department (ED) overcrowding is a global concern. To help mitigate this issue, this thesis studies impediments to efficient patient flow in the ED caused by suboptimal worker behaviors and patient routing policies. I focus on three issues: (i) admission batching, (ii) hallway placement and (iii) under-triage behavior, and empirically demonstrate their impact on patient flow and quality of care. These studies are summarized as follows. Admissions batching: We study the behavior of admitting patients back-to-back (i.e., batching) by ED physicians. Using data from a large hospital, we show that the probability of batching admissions is increasing in the hour of an ED physician’s shift, and that batched patients experience a longer delay from hospital admission to receiving an inpatient bed. We further show that this effect is partially due to the increase in the coefficient of variation of inpatient bed-requests caused by batching. However, we also find that batching admissions is associated with a higher shift-level productivity. An important implication of our work is that workers may induce delays in downstream stages, caused by practices that increase their productivity. Hallway utilization: A common practice in busy EDs is to admit patients from the waiting area to hallway beds as the regular beds fill up. Using data from a large ED, we first perform a causal analysis to quantify the impact of hallway placement on wait times and quality of care – as defined by disposition time, room-to-departure (R2D) time and likelihood of adverse outcomes. We find that patients admitted to the hallway experience a significantly lower door-to-doctor time at the cost of longer disposition and R2D times. Hallway patients are also substantially more likely to experience an adverse outcome. Next, using a counterfactual analysis we show that a pooling policy, where hallway beds are used only if all regular beds are full, significantly reduces wait times, albeit at the cost of a slightly higher hallway utilization. Also, too little or too much wait tolerance for rooming patients may result in under- or over-utilization of the hallway space, both of which are detrimental to overall ED length of stay (LOS) and wait times. Under-triage behavior: Triaging ED patients upon arrival to the ED and assessing their urgency for treatment is crucial for timely service to all patients. Despite the standard patient classification algorithm by which all nurses are trained, we hypothesize, and show, that the ED’s workload impacts the perceived patient urgency, and subsequently, patient severity scores. We first use a predictive model to predict a patient’s true triage level using information collected at triage and define under-triage, accordingly. We find that under-triage is decreasing up to a certain point of workload but increasing after (U-shape). We also quantify the impact of under-triage on disposition time, room-to-departure time and risk of readmission. Collectively, this thesis demonstrates how patient-flow may be improved without the need to increase explicit physical capacity in the ED (e.g., beds). It offers practical solutions to managers and contributes to the operations management literature.

Depuis une vingtaine d'années, les problématiques de transport public en région parisienne sont devenues une préoccupation majeure. Pour les usagers qui consacrent en moyenne environ deux heures quotidiennement à leurs déplacements domicile-travail, la qualité de l'offre de transport est un enjeu majeur.La société nationale des chemins de fer français qui exploitent la majeure partie du réseau ferré dans cette région joue un rôle central dans l'organisation des transports. Mais à l'opposé des attentes qui pèsent sur ce secteur, le trafic ferroviaire rencontrent un certain nombre de dysfonctionnements. En s'inscrivant dans une démarche globale de remise en question des principes d'exploitation ferroviaire en zone dense, cette thèse apporte un regard nouveau sur l'origine des retards qui affectent les trains.Un modèle simple qui permet d'étudier la congestion du trafic ferroviaire sous l'influence de perturbations aléatoires est proposé. En s'inspirant des outils du trafic routier et tout particulièrement du diagramme fondamental de réseau,on définit pour le ferroviaire, le diagramme fondamental de ligne ferroviaire qui permet de représenter le débit en fonction de la concentration sur une portion de ligne ferroviaire. Cet outil est ensuite utilisé pour comparer les résultats issus de notre modèle à un jeu de données mesuré sur deux lignes de chemin de fer de la région parisienne.Cette comparaison montre que notre modèle permet de reproduire qualitativement les phénomènes de congestion du trafic observés sur les cas réels. / Over the last twenty years, public transport issues in the Paris region have become a major concern. The French national railway company, which operates most of the rail network in this region, plays a central role in the organisation of transport. However, in contrast to expectations in this sector, rail traffic is experiencing a number of malfunctions. As part of an overall approach to questioning the principles of rail operation in dense areas, this thesis provides a new look at the origin of delays affecting trains. Drawing on road traffic tools and in particular the basic network diagram, the basic railway line diagram is defined for railways, which makes it possible to represent the flow as a function of concentration on a portion of a railway line. This tool is then used to compare the results from our model with a set of data measured on two railway lines in the Paris region, which shows that our model can qualitatively reproduce the traffic congestion phenomena observed on real cases.(Translated with www.DeepL.com/Translator)

<p>Kunskap om grundvattenbildningen är nödvändig för att man ska kunna förutsäga konsekvenserna av grundvattenuttag och underjordsbyggande. Grundvattenbildningen i berggrunden är dock svår att uppskatta. Syftet med avhandlingen var att öka förståelsen av grundvattenbildningen i kristallin berggrund, att undersöka hur grundvattenbildningen ska uppskattas samt att utveckla nya modeller för att beskriva grundvattenbildningen. Studien grundades på tre angreppssätt: grundvattendatering med freoner (CFC), geohydrauliska observationer och matematisk modellering.</p><p>Koncentrationerna av CFC-11 och CFC-113 befanns vara låga i det undersökta berggrundvattnet, vilket i kombination med låga syrgashalter tyder på anaerob nedbrytning. Koncentrationerna av CFC-12 och tritium överensstämde ganska väl, vilket betyder att den skenbara åldern kan vara den sanna åldern. Resultaten tyder på att CFC-datering inte är pålitlig i skogsmiljöer med finkornigt jordtäcke.</p><p>Vid nederbörd observerades ett snabbt gensvar i den hydrauliska potentialen i den studerade bergakviferen, trots det 10 m mäktiga moräntäcket. En avsevärd del av de observerade potentialvariationerna befanns vara belastningseffekter, som inte innebar någon magasinsförändring eller något vattenflöde. Berggrundens belastningseffektivitet uppskattades, ur potentialens svar på lufttrycksförändringar, till 0,95. Ytbelastningen beräknades från mätningar av lufttryck, vatten i jordtäcket och snö. Omkring 20 % av årstidsvariationen hos den hydrauliska potentialen uppskattades bero på enbart belastningsförändringar. En enkel begreppsmässig modell kunde användas för att simulera den observerade hydrauliska potentialen. För att beskriva enskilda grundvattenbildningstillfällen på bästa sätt var det nödvändigt att ta hänsyn till effekten av ytbelastningen.</p><p>Numeriska experiment gjordes med en modell av en jord–bergprofil. När berget modellerades som ett heterogent kontinuum bildades omättade zoner i berget vid stora hydrauliska gradienter. Fenomenet uppträdde i områden där låggenomsläppliga zoner låg uppströms höggenomsläppliga zoner, och ledde till minskad hydraulisk konduktivitet i berget.</p> / <p>Knowledge about the groundwater recharge is essential for the prediction of impacts of groundwater withdrawal and underground construction. Recharge in the bedrock is, however, difficult to estimate. The objectives of this thesis were to increase the understanding of groundwater recharge in crystalline bedrock, to investigate how the recharge could be estimated, and to develop new models to describe the recharge. The study was based on three approaches: groundwater dating using chlorofluorocarbons (CFCs), geohydraulic field measurements, and mathematical modelling.</p><p>Low concentrations of CFC-11 and CFC-113 were found in the bedrock groundwater, which in combination with low dissolved-oxygen levels indicated anaerobe degradation. The CFC-12 and tritium concentrations agreed fairly well, which means that apparent ages could be true ages. The results suggest that CFC dating may not be reliable at forested, humid sites covered by fine-grained soil.</p><p>A quick response in hydraulic head to precipitation was observed in the studied bedrock, despite the 10-m thick till cover. A substantial portion of observed head variations was found to be loading effects, involving no storage changes or water flow. The loading efficiency of the bedrock was estimated, from the air-pressure response, to be 0.95. The surface loading was calculated from measurements of air pressure, water in the soil, and snow. About 20% of the seasonal variation of the hydraulic head was estimated to be related to loading changes only. A simple conceptual model could be used to simulate the observed hydraulic heads. The loading effect had to be included to properly describe individual recharge events.</p><p>Numerical experiments were performed with a soil–bedrock profile. When the rock was modelled as a heterogeneous continuum, unsaturated zones developed at high hydraulic gradients. The phenomenon appeared in areas where low-conductive zones were located upstream of high-conductive zones, decreasing the effective hydraulic conductivity of the material.</p>

<p>The decrease in number and area of managed hay-meadows over the last century, in combination with the reduction of traditional management, threatens the biodiversity connected to these habitats. I experimentally examined how management intensity affected meadow characteristics and long-term population viability of three vascular plant species in wooded hay-meadows on the Swedish island of Gotland in the Baltic Sea. I discovered that intensified management (extra raking and/or extra mowing) reduced the amount of litter and biomass, even in well-managed meadows. </p><p>The effects of intensified management on population growth rate varied among species. Deterministic demographic models revealed that intensified management increased population growth rate in <i>Succisa pratensis</i>. Stochastic modelling confirmed this; all meadows displayed larger projected population sizes 50 years into the future with intensified management. <i>Polygala amarella</i> responded with lower growth rates in raked plots, a consequence of the plant’s morphology, which makes it prone to being pulled out by raking. <i>Hypochoeris maculata</i> had population growth rates close to unity, and showed no response to an increase in management. Examination of the life-history characteristics of <i>Polygala amarella</i> showed that the species’ strategy is aimed at reproduction and fast growth, which is in contrast to the other two species, with their success relying on the survival of older plants. The species-specific responses to management show that several species should be considered when evaluating management practices for conservation of semi-natural grasslands. Furthermore, I suggest that data on stage distributions alone may not be sufficient for identifying threatened populations.</p><p>In a study of artificial dispersal between meadows, I found that establishment was twice as successful for planted plug-plants compared to sown seeds. Both methods may be useful for introducing or augmenting meadow populations, depending on access to seed sources and possibilities to nurse plants.</p><p>An electronic coordinate measurement device for gathering location data to be used in demographic studies was developed. In the field, the device proved to be a simple and reliable method for locating individuals in permanent plots.</p>

Kunskap om grundvattenbildningen är nödvändig för att man ska kunna förutsäga konsekvenserna av grundvattenuttag och underjordsbyggande. Grundvattenbildningen i berggrunden är dock svår att uppskatta. Syftet med avhandlingen var att öka förståelsen av grundvattenbildningen i kristallin berggrund, att undersöka hur grundvattenbildningen ska uppskattas samt att utveckla nya modeller för att beskriva grundvattenbildningen. Studien grundades på tre angreppssätt: grundvattendatering med freoner (CFC), geohydrauliska observationer och matematisk modellering. Koncentrationerna av CFC-11 och CFC-113 befanns vara låga i det undersökta berggrundvattnet, vilket i kombination med låga syrgashalter tyder på anaerob nedbrytning. Koncentrationerna av CFC-12 och tritium överensstämde ganska väl, vilket betyder att den skenbara åldern kan vara den sanna åldern. Resultaten tyder på att CFC-datering inte är pålitlig i skogsmiljöer med finkornigt jordtäcke. Vid nederbörd observerades ett snabbt gensvar i den hydrauliska potentialen i den studerade bergakviferen, trots det 10 m mäktiga moräntäcket. En avsevärd del av de observerade potentialvariationerna befanns vara belastningseffekter, som inte innebar någon magasinsförändring eller något vattenflöde. Berggrundens belastningseffektivitet uppskattades, ur potentialens svar på lufttrycksförändringar, till 0,95. Ytbelastningen beräknades från mätningar av lufttryck, vatten i jordtäcket och snö. Omkring 20 % av årstidsvariationen hos den hydrauliska potentialen uppskattades bero på enbart belastningsförändringar. En enkel begreppsmässig modell kunde användas för att simulera den observerade hydrauliska potentialen. För att beskriva enskilda grundvattenbildningstillfällen på bästa sätt var det nödvändigt att ta hänsyn till effekten av ytbelastningen. Numeriska experiment gjordes med en modell av en jord–bergprofil. När berget modellerades som ett heterogent kontinuum bildades omättade zoner i berget vid stora hydrauliska gradienter. Fenomenet uppträdde i områden där låggenomsläppliga zoner låg uppströms höggenomsläppliga zoner, och ledde till minskad hydraulisk konduktivitet i berget. / Knowledge about the groundwater recharge is essential for the prediction of impacts of groundwater withdrawal and underground construction. Recharge in the bedrock is, however, difficult to estimate. The objectives of this thesis were to increase the understanding of groundwater recharge in crystalline bedrock, to investigate how the recharge could be estimated, and to develop new models to describe the recharge. The study was based on three approaches: groundwater dating using chlorofluorocarbons (CFCs), geohydraulic field measurements, and mathematical modelling. Low concentrations of CFC-11 and CFC-113 were found in the bedrock groundwater, which in combination with low dissolved-oxygen levels indicated anaerobe degradation. The CFC-12 and tritium concentrations agreed fairly well, which means that apparent ages could be true ages. The results suggest that CFC dating may not be reliable at forested, humid sites covered by fine-grained soil. A quick response in hydraulic head to precipitation was observed in the studied bedrock, despite the 10-m thick till cover. A substantial portion of observed head variations was found to be loading effects, involving no storage changes or water flow. The loading efficiency of the bedrock was estimated, from the air-pressure response, to be 0.95. The surface loading was calculated from measurements of air pressure, water in the soil, and snow. About 20% of the seasonal variation of the hydraulic head was estimated to be related to loading changes only. A simple conceptual model could be used to simulate the observed hydraulic heads. The loading effect had to be included to properly describe individual recharge events. Numerical experiments were performed with a soil–bedrock profile. When the rock was modelled as a heterogeneous continuum, unsaturated zones developed at high hydraulic gradients. The phenomenon appeared in areas where low-conductive zones were located upstream of high-conductive zones, decreasing the effective hydraulic conductivity of the material.

The decrease in number and area of managed hay-meadows over the last century, in combination with the reduction of traditional management, threatens the biodiversity connected to these habitats. I experimentally examined how management intensity affected meadow characteristics and long-term population viability of three vascular plant species in wooded hay-meadows on the Swedish island of Gotland in the Baltic Sea. I discovered that intensified management (extra raking and/or extra mowing) reduced the amount of litter and biomass, even in well-managed meadows. The effects of intensified management on population growth rate varied among species. Deterministic demographic models revealed that intensified management increased population growth rate in Succisa pratensis. Stochastic modelling confirmed this; all meadows displayed larger projected population sizes 50 years into the future with intensified management. Polygala amarella responded with lower growth rates in raked plots, a consequence of the plant’s morphology, which makes it prone to being pulled out by raking. Hypochoeris maculata had population growth rates close to unity, and showed no response to an increase in management. Examination of the life-history characteristics of Polygala amarella showed that the species’ strategy is aimed at reproduction and fast growth, which is in contrast to the other two species, with their success relying on the survival of older plants. The species-specific responses to management show that several species should be considered when evaluating management practices for conservation of semi-natural grasslands. Furthermore, I suggest that data on stage distributions alone may not be sufficient for identifying threatened populations. In a study of artificial dispersal between meadows, I found that establishment was twice as successful for planted plug-plants compared to sown seeds. Both methods may be useful for introducing or augmenting meadow populations, depending on access to seed sources and possibilities to nurse plants. An electronic coordinate measurement device for gathering location data to be used in demographic studies was developed. In the field, the device proved to be a simple and reliable method for locating individuals in permanent plots.

Understanding groundwater flow systems and how these control transport is an essential part in assessing the suitability of subsurface environments as hosts for storage of toxic waste. Therefore it is important to be able to integrate knowledge obtained from field characterisation of the subsurface with methods which can be used to evaluate and predict possible impact on surrounding environments.In this thesis I investigate the characteristics of flow and transport in discrete fracture networks by analysing Eulerian and Lagrangian descriptions within a stochastic framework. The analysis is conducted through numerical flow and transport simulations configured according to available field data, combined with independent theoretical analytic and semi-analytic methods which are able to reveal insight to relevant constitutive properties. It is shown that numerical simulations conducted with the discrete fracture network approach can be both conditioned and confirmed against field measurable quantities, and the developed theoretical methods are evaluated against results obtained from simulation. Thereby, a methodology which can provide links between field measurable quantities and tracer discharge is presented, developed and evaluated. It is shown to be robust with respect to underlying assumptions used for flow configurations.In particular, a specific sampling algorithm for obtaining a Lagrangian description of transport based on a Eulerian description of flow is proposed, evaluated and shown to be robust for the cases considered, providing accurate replications. Also a generalisation of both the advection-dispersion solution and the one-sided stable distribution is shown to be able to evaluate advective transport quantities, and combined with a Lagrangian retention model it is shown to be a fairly accurate and robust method for upscaling distributions, enabling predictions of transport in terms of tracer discharge. Evaluation of transport is also conducted against the advective-dispersion assumption, where results indicate advective transport is generally non-Fickian for the fracture networks and domain scales considered, but not necessarily anomalous. Additionally, the impact certain model assumptions have on tracer discharge are analysed. For example, transport is evaluated for assumptions regarding injection mode, fracture network heterogeneity, relationship between aperture and transmissivity, relationship between transmissivity and size, as well as scale and modelling dimension. In relation to hydraulic testing and flow analysis, a method for conditioning fracture transmissivity from field measurements of flow by simulation is developed and evaluated against homogenisation assumptions commonly used in field applications. Results indicate the homogenisation assumption generally fails for current interpretations of field data. / Miljökonsekvensbedömningar av toxiskt avfall i djupt bergförvar kräver engrundläggande förståelse av grundvattenströmning samt hur detta påverkartransportfenomet. Därför är det viktigt att kunna integrerafältundersökningsdata från berggrundsmätningar med metoder som kan användas föratt utvärdera och förutsäga potentiella konsekvenser på omgivningen.I denna avhandling undersöker jag flödes- och transportegenskaper i diskretaspricknätverk genom stokastisk analys av eulerska och lagrangeskafältbeskrivningar. Analysen sker genom en kombination av dels numeriska flödes-och transportsimuleringar som är konfigurerade enligt tillgänglig fältdata, samtdels med oberoende teoretiska analytiska och semi-analytiska metoder som gerdjupare insyn i relevanta konstitutiva egenskaper. Resultat visar att dennumeriska simuleringsmetoden för diskreta spricknätverk kan både konditionerastill fältdata och bestyrkas gentemot mätbara kvantiter. Detta är av betydelse dåde teoretiska metoderna i sin tur är främst evaluerade gentemotsimuleringsresultat. Därmed utvecklas en bestyrkt metodik som kansammanlänka och i viss mån omvandla fältdata till uppskattningar av mängdenspårämnen i ett utflöde. Resultat indikerar att denna metodik är robust avseendeflera antaganden som har används i simuleringskonfigurationen.En särskild urvalsalgoritm introduceras som kan erhålla en lagrangesktransportbeskrivning utifrån ett eulerskt strömningsfält. även denna utvärderasavseende vissa simuleringsantaganden och resultat tyder på att den är robust förde undersökta fallen. Vidare föreslås en viss generalisering av lösningen tillden advektiva-dispersionsekvationen samt av ensidigt stabila (one-sided stable)sannolikhetsfördelningar som metod för att prediktera advektiva kvantitetergenom upskalning av transportfördelningar i rummet. Denna modell kombineras meden tidigare utvecklad metod för transportretention för att uppskatta reaktivagenombrottsfördelningar. Således blir det möjligt att prediktera reaktivtransport d v s rumslig upskalning av genombrottstider för spårämnestransport.Metoden används också för att evaluera ett linärt dispersionsantagande, därresultat indikerar att även advektiv transport kan påvisa icke-linärt beteende.Transport i spricknätverk utvärderas bland annat för modellantaganden avseendeinjektionsmetod, heterogenitet i spricknätverk, konstitutiva relationer mellanapertur och transmissivitet samt mellan transmissivitet och spricklängd, ochmodelleringsskala samt dimension. Beträffande hydrauliska testmetoder ochflödesanalys introduceras en simuleringsmetod för att konditioneraspricktransmissivitet från flödesmätningar. Detta jämförs med etthomogeniseringsantaganden som inte sällan används i fältundersökningar för atttolka flödesmätningar till spricktransmissivitet, och resultat tyder på attdetta antagande kan betydligt undervärdera transmissivitet.

One of the most unforgiving processes in nature is that of Muller's ratchet, a seemingly irreversible accumulation of deleterious mutations that all organisms have to deal with or face extinction. The most obvious way to avoid fitness collapse is recombination, though asexual populations usually do not have the luxury of recombining freely.  With the aid of computational and mathematical models, we have studied other situations where this threat is averted and the organism can survive the ratchet. The results show that a ratchet where all mutations have the same deleterious fitness effect is very effectively stalled for large effects. However, if mutations are allowed to have a broad range of effects, the fitness-loss rate can be substantial even with the same mean effect as the one-type ratchet, but we have  identified parameter regions where even the broad-range effects are effectively stopped. The fitness-loss from a ratchet is very sensitive to the mutation rate and a mutation that increases the mutation rate (mutator) can easily start an otherwise stalled ratchet. Large effect mutators are heavily counter-selected, but smaller mutators can spread in the population. They can be stopped by reversals (antimutators), but even if the mutation rate is equilibrated in this way, there will be large fluctuations in mutation rate and even larger in the fitness-loss rate due to the feedback amplification in their coupling.    Another way of preventing the ratchet is by reversal of the deleterious mutations themselves through back-mutations or compensatory mutations. The rate required to stop the ratchet using only back-mutations before the fitness collapses is very large. A detailed comparison between the deleterious mutations in the ratchet and in a sexual population was made and the difference was found to be greatest for large populations with large genomes. There are obviously many ways to survive the ratchet, but even more ways to drive a species to extinction by enhancing and speeding up the ratchet. By modelling and testing the ratchet for numerous different situations, we show the effects of some of these threats and benefits.

L'étude de la dynamique des réseaux de réactions est un enjeu majeur de la biologie des systèmes. Cela peut-être réalisé de deux manières : soit de manière déterministe à l'aide d'équations différentielles, soit de manière probabiliste à l'aide de chaînes de Markov. Dans les deux cas, un problème majeur est celui de la détermination des lois cinétiques impliquées et l'inférence de paramètres cinétiques associés. Pour cette raison, l'étude directe de grands réseaux de réactions est impossible. Dans le cas de la modélisation déterministe, ce problème peut-être contourné à l'aide d'une analyse stationnaire du réseau. Une méthode connue est celle de l'analyse des flux à l'équilibre (FBA) qui permet d'obtenir des systèmes de contraintes à partir d'informations sur les pentes moyennes des trajectoires. Le but de cette thèse est d'introduire une méthode analogue dans le cas de la modélisation probabiliste. Les résultats de la thèse se divisent en trois parties. Tout d'abord on présente une analyse stationnaire de la modélisation probabiliste reposant sur une approximation de Bernoulli. Dans un deuxième temps, cette dynamique approximée nous permet d'établir des systèmes de contraintes à l'aide d'informations obtenues sur les moyennes, les variances et les co-variances des trajectoires du système. Enfin, on présente plusieurs applications à ces systèmes de contraintes telles que la possibilité de réfuter des réseaux de réactions à l'aide d'informations de variances ou de co-variances et la vérification formelle de propriétés logiques sur le régime stationnaire du système. / A major goal in systems biology is to inverstigate the dynamical behavior of reaction networks. There exists two main dynamical frameworks : the first one is the deterministic dynamics where the dynamics is described using odinary differential equations, the second one is probabilistic and relies on Markov chains. In both cases, one major issue is to determine the kinetic laws of the systems together with its kinetic parameters. As a consequence the direct study of large biological reaction networks is impossible. To deal with this issue, stationnary assumptions have been used. A widely used method is flux balance analysis, where systems of constraints are derived from information on the average slopes of the system trajectories. In this thesis, we construct a probabilistic analog of this stationnary analysis. The results are divided into three parts. First, we introduce a stationnary analysis of the probabilistic dynamics which relies on a Bernoulli approximation. Second, this approximated dynamics allows us to derive systems of constraints from information about the means, variances and co-variances of the system trajectories. Third, we present several applications of these systems of constraints such as the possibility to reject reaction networks using information from experimental variances and co-variances and the formal verification of logical properties concerning the stationnary regime of the system.