Academic literature on the topic 'Ends effects'

The first chapter of this dissertation evaluates changes in fuel procurement practices by coal- and natural gas-fired electricity generating plants in the United States following state-level legislation that ended cost-of-service regulation. I construct a detailed dataset that links confidential, shipment-level data on the price of virtually all of the fuel delivered to coal- and gas-fired electricity plants in the United States from 1990-2009, with plant-level data on operations and regulatory status. I find the price of coal drops by 12% at deregulated plants relative to matched plants that were not subject to any regulatory change, whereas there was no relative drop in the price of gas. I show how my results lend support to theories of asymmetric information between generators and regulators, regulatory capture, and capital-bias as important sources of distortion under cost-of-service regulation. The second chapter analyses changes in the cost of generating electricity following the introduction of regional wholesale electricity markets. I use proxy methods based on Olley and Pakes (1996); Levinsohn and Petrin (2003) to estimate fuel-specific production functions, and construct the Olley-Pakes productivity index to decompose costs in to within-plant productivity and allocative efficiency changes. I then apply a potential outcomes framework to the derived productivity estimates, allowing the construction of counterfactual costs that explicitly account for permanent differences between market and non-market areas and common transitory shocks. I find that the introduction of market-based dispatch methods has reduced fossil-fuel production costs by upwards of 15%. The third chapter is based on joint work with Roland Fryer and Jorg Spenkuch. We develop a Roy model in which individuals sort into peer groups based on comparative advantage. Two key results emerge: First, when comparative advantage is the guiding principle of peer group organization, the effect of moving a student into an environment with higher-achieving peers depends on where in the ability distribution she falls and the effective wages that clear the social market. As a result, linear in means estimates of peer effects are not identified. We show that the model’s testable prediction in the presence of this confounding issue is borne out in two data sets.<br>Economics

Differential scanning calorimetry (DSC) melting analysis was performed on 27 short double stranded DNA duplexes containing 15 to 25 base pairs and short single stranded overhangs from one to 10 bases, on both ends. Molecules have two 5' dangling ends or one 5' and one 3' dangling end. For these molecules the duplex region was incrementally reduced from 25 to 15 base pairs with increased length of the dangling ends from one to 10 bases. A third set of molecules contained 21 base pair duplexes with a four base dangling end on either the 5' or 3' end. Blunt ended duplexes from 15 to 25 base pairs were also examined and served as control duplexes. DSC melting curves were measured in solution containing 85 mM, 300 mM or 1.0 M Na+. From these measurements, thermodynamic parameters for 5' and 3' dangling ends as a function of end length were evaluated. Results showed the 5' ends were slightly stabilizing, and this stability was essentially constant with end length, while the 3' ends were generally destabilizing with increasing length of the end. This finding of lower stability for the 3' ends is consistent with results of published studies that have found 5' dangling ends to be more than or equally as stabilizing as 3' dangling ends. Our finding that 3' dangling ends are actually destabilizing for duplex DNA contrasts with published results. The 3' ends also display a stronger dependence on the [Na+]. In the lower Na+ environment the 3' ends are more destabilizing than at the higher salt environments. Analysis of the thermodynamic parameters of the dangling-ended duplexes as a function [Na+] indicated the 3' dangling end molecules behave differently compared to 5' dangling ended and blunt ended duplexes. The net counterion release per phosphate upon melting the molecules having one 5' and one 3' end was approximately 15% smaller as a function of end length compared to the duplex having two 5' ends. Further analysis of the DSC evaluated thermodynamic transition parameter, ΔHcal, and its relationship to the measured transition temperatures of the DNA molecules, provided an estimate on the excess heat capacity differences, ΔCp, between duplex and melted single strands for the dangling-ended molecules. The analysis revealed the molecules with one 5' and one 3' dangling end had very different ΔCp values compared to the blunt-ended molecule; while the molecules with two 5' ends have ΔCp that are essentially the same as the blunt-ended duplex. These observations are interpreted as differences in the interactions with Na+, solvent and the terminal base pairs of the duplex for the 5' versus 3' dangling ends.

DNA double strand breaks (DSBs ) are extremely toxic to cells because they can lead to genomic rearrangements and even cell death. Two main pathways can repair DSBs: the homologous recombination repair (HRR) pathway and the non-homologous end-joining (NHEJ) pathway. NHEJ is the primary repair pathway in mammalian cells. HRR repairs single strand breaks (SSBs) or DSBs, mostly during late S phase and G2 phase of the cell cycle, by using an undamaged copy of the DNA sequence, and is therefore largely error-free, while the NHEJ pathway repairs DSBs without the requirement for sequence homology, may be error-free or error-prone, and is most active during G1 phase. Thymine glycol (Tg), the most common oxidation product of thymine. It produced endogenously as a consequence of aerobic metabolism or via exogenous factors such as ionizing radiation (IR), it is one of the predominant types of base modifications produced by ionizing radiation. Due to clustering of radiation – induced ionizations, Many DSBs induced by ionizing radiation bear damaged bases, including (Tg) moieties at or near the DSB ends that may interfere with subsequent gap filling and ligation. Artemis is a nuclease that is involved in the processing of termini during repair of DSBs and in modifying termini of complex DSBs. It has 5′–3′ exonuclease activity specific for single- stranded DNA, but, in the presence of DNA-PK, Artemis demonstrates endonuclease activity that is utilized in the removal of 3′ phosphoglycolate termini and 5′ overhangs, in the shortening of 3′ overhangs at DSBs, and in the opening of hairpin ends. To assess the ability of NHEJ to rejoin DSBs accompanied by Tg lesions and to elucidate the aspects of the possible role of Artemis in DSB repair, linearized plasmids with Tg either at the 3’ terminus of a blunt end (designated Tg1) or three or two bases from the end (Tg3 and Tg2, respectively), were subjected to a repair assay using XRCC4-like factor (XLF) deficient cell extracts, with or without the addition of XLF and/or Artemis, EndoIII and ddTTP. The data indicated that, the cell extract could ligate the plasmids with Tg1 and Tg2 with extremely low efficiency but could repair plasmid with Tg3 as efficiently as unmodified plasmid. In addition, Plasmids with Tg1and Tg2 were treated with Endonuclease III and ddTTP to test whether the end joining occurred before or after Tg removing, neither one had any effects on plasmids with Tg1. However, plasmids with Tg2 showed reduced in the intensity upon treatment with Endonucleases III and ddTTP, which suggested some ligation occur while Tg still present. In Artemis reaction, substrate with Tg2 and Tg3 could stimulate Artemis mediated trimming but not Tg1. Addition of EndoIII or ddTTP to plasmid with Tg3 resulted in a significant decrease in the intensities of the bandsrepresenting ligated products compared to XLF alone, suggesting that in some of the ligated products Tg are still present, while in others Tg had been removed and replaced by polymerization with normal nucleotides. Taken together, our results indicated that cell extract could ligate the plasmid with Tg located at the third base to DSB with high efficiency compared to plasmids with Tg1 and Tg2 which apparently this ability was severely inhibited when it located at or in the second position to DSB ends. Moreover, Artemis is also capable of trimming of thymine glycol at the second or third position from DSB ends with limited capability but inhibited by the presence of thymine glycol at the break site.

Les préoccupations actuelles concernant l'exploitation sécuritaire des centrales nucléaires existantes et la conception d’architectures spéciales envisagées pour la quatrième génération de réacteurs nucléaires se combinent avec l’intérêt plus prononcé pour l'efficacité et la fiabilité de l'équipement d'un système énergétique. Cela fait que dans un souci de meilleure compréhension et optimisation basée sur des moyens modernes de conception assistée par l’ordinateur, l'étude de différentes parties de ces systèmes fait de plus en plus l’objet de recherches approfondies. . Parmi les types proposés pour la quatrième génération de réacteurs nucléaires font partie ceux ayant comme agent de refroidissement les sels fondus, respectivement le sodium fondu. En raison de leurs propriétés physiques, les sels fondus et le sodium liquide ont le potentiel d'être déplacés par les pompes électromagnétiques. Cet ouvrage est à la fois une étude approfondie des phénomènes qui se produisent en raison de l'écoulement du fluide dans le champ électromagnétique d’une pompe électromagnétique - interaction magnétohydrodynamique - et un rapport sur les capacités et les avantages des outils informatiques modernes pour faciliter la conception et l'optimisation des pompes électromagnétiques. Afin d’atteindre l'objectif principal de la thèse, notamment une meilleure compréhension des phénomènes interdépendants spécifique à l’opération des pompes électromagnétiques, deux objectifs secondaires ont été considérés. Le premier objectif concerne la pleine exploitation des modèles électromagnétiques numériques en éléments finis afin d'obtenir autant d'informations que possible sur le comportement des pompes électromagnétiques, dans l’hypothèse où on ne tient pas compte de l'écoulement des fluides. Le deuxième objectif était la construction des modèles numériques qui réunissent l’électromagnétisme et la dynamique des fluides, respectivement des modèles numériques qui regroupent les deux phénomènes caractérisant l’écoulement magnétohydrodynamique dans les canaux des pompes électromagnétiques. Dans l'étude dédiée au pompage électromagnétique de sels fondus, la thèse met en évidence des problèmes spécifiques liés à la génération de forces électromagnétiques dans les fluides faibles conducteurs d'électricité et fournit des résultats sur les applications où le pompage électromagnétique de sels fondus peut être efficace. À l’aide des modèles électromagnétiques nous avons obtenu des informations importantes sur l'influence du nombre de pôles électromagnétiques et de la fréquence d’alimentation sur la caractéristique Pression - Vitesse des pompes annulaires à induction. Ils ont été analysés le phénomène de blindage créé par les parois métalliques - avec des répercussions négatives sur les performances de la pompe, les effets de freinage exercés à l'entrée et à la sortie du canal de la pompe et la relation entre la capacité de surcharge hydrodynamique et la caractéristique Pression - Vitesse des pompes à induction. Une section spéciale a été consacrée à l'analyse de la dépendance de la force électromagnétique du temps et de l’espace et à l’étude de non-uniformitées des quantités de nature électromagnétique en direction azimutale dans les pompes annulaires à induction.Dans le chapitre qui traite de l'interaction magnétohydrodynamique à base de modèles couplés, ils sont proposés deux modèles qui couplent l'électromagnétisme et l’écoulement. Ils sont présentés les avantages des modèles couplés, en matière de la précision des résultats, par rapport aux modèles électromagnétiques. Il est également présenté l'évolution des profils de vitesse, de densité de force et de courant sous l'influence du champ électromagnétique et de l’écoulement de sodium à vitesses différentes. Les contributions de la thèse sont complétées par des observations importantes sur les méthodes de travail et les logiciels utilisés tout au long de l'étude<br>The actual concerns with respect to safe operation of existing nuclear plants and to designing special architectures envisaged for the fourth generation of nuclear reactors, corroborated with the increasing interest for efficiency and reliability of any equipment belonging to an energetic system, make that more and more research endeavors to be devoted to the study of various parts of these systems for a better understanding and optimization based on modern techniques of computer aided design. Among the types proposed for the fourth generation of nuclear reactors belong those that have as cooling agent molten salts, respectively liquid sodium. Many reactors of previous generations use mechanical pumps of special design for driving the coolants. Molten salts and liquid sodium, thanks to their physical properties, have the potential to be driven using electromagnetic pumps. Although the technology of electromagnetic pumping of electroconductive fluids was developed since the first half of the last century, currently it undergoes a revival due to the reconsideration of its multiple technological and security advantages. This work is both an intimate study of the phenomena that occur as a result of the electroconductive fluids flow in the electromagnetic field of an electromagnetic pump – magnetohydrodynamic interaction - and a report on the capabilities and advantages of modern computational tools to facilitate design and optimization of electromagnetic pumps.To achieve the principal goal of deeper understanding of the interdependent phenomena specific to electromagnetic pumps operation, two auxiliary objectives were considered. The first is related to the full exploitation of electromagnetic finite element models in order to retrieve as much information as possible about electromagnetic pumps behavior in a simplifying hypothesis that does not take into account the fluid dynamics. The second auxiliary objective is to build numerical models that couple the electromagnetism and the fluid dynamics, namely the two interdependent physics that govern the magnetohydrodynamic flow through channels of electromagnetic pumps.In the section dealing with the study of electromagnetic pumping of molten salts, the thesis highlights specific problems related the generation of electromagnetic forces in fluids with low electrical conductivity and provides results with respect to applications where electromagnetic pumping of molten salts can be effective. With the electromagnetic numerical models were obtained important data about the influence of the number of electromagnetic poles and supply frequency on the Pressure – Velocity characteristic of annular linear induction pumps. Were analyzed the shielding effect generated by the metallic walls - with negative repercussions on pumps performances, braking effects exerted at pump inlet and pump outlet and the connection between the overload capacity and Pressure – Velocity characteristic of induction pumps. A special portion was devoted to the analysis of the time and space dependence of the electromagnetic force and to the study of the non-uniformities of electromagnetic quantities in azimuth direction of annular linear induction pumps.In the chapter devoted to the magnetohydrodynamic interaction through coupled models, the thesis proposes two models that couple the electromagnetism and the fluid flow, one realized using multiphysic software and the second by coupling two different softwares. There are presented the advantages of the coupled models with respect to the results accuracy in comparison with electromagnetic models. It is presented the evolution of velocity, force and current densities profiles under the influence of the electromagnetic field and of different sodium mean velocities.The contributions of the thesis are completed with significant observations related to the study methods and software tools used along the study process<br>Preocupările actuale în legătură cu exploatarea în siguranță a centralelor nucleare existente și în legătură cu proiectarea arhitecturilor speciale de reactoare nucleare pentru generația a patra,coroborate cu interesul tot mai pronunțat pentru eficiența și fiabilitatea oricărui echipament dintr-un sistem energetic, fac ca tot mai multe demersuri de cercetare să se îndrepte spre studiul diverselor subansamble ale acestor sisteme pentru o mai buna înțelegere și optimizare pe baza mijloacelor moderne de proiectare asistată de calculator. Din rândul tipurilor propuse pentru generația a patra de reactoare nucleare fac parte și cele care au ca agent de răcire săruri topite, respectiv sodiu topit. Multe reactoare nucleare de generație anterioară folosesc ca mijloc de antrenare a fluidelor de răcire pompe mecanice de construcție specială. Sărurile topite ăi sodiul lichid, datorită proprietăților fizice,au potențialul de a fi recirculate cu ajutorul pompelor electromagnetice. Deși tehnologia pompării electromagnetice a fluidelor electroconductoare a fost dezvoltată încă din prima parte a secolului trecut, în prezent cunoaște o renaștere datorită reconsiderării multiplelor avantaje tehnologice și de securitate în exploatare. Lucrarea de față este atât un studiu al fenomenelor intime ce au loc ca urmare a curgerii fluidelor electroconductoare în câmpul electromagnetic al pompelor electromagnetice – interacțiune magnetohidrodinamică - cât și un raport despre capabilitățile și avantajele uneltelor moderne de calcul de a înlesni proiectarea și optimizarea pompelor electromagnetice. Pentru a atinge scopul principal al tezei, și anume o înțelegere mai adâncă a fenomenelor interdependente specifice funcționării pompelor electromagnetice, au fost considerate două obiective secundare. Primul obiectiv se referă la exploatarea la maximum a modelelor electromagnetice numerice în element finit cu scopul de a obține cât mai multe informații cu putință despre comportamentul pompelor electromagnetice în ipoteza care nu ia în considerare curgerea fluidelor. Al doilea obiectiv a fost construirea unor modele numerice care cuplează electromagnetismul și curgerea, respectiv, cuplează modelele numerice ale celor două fenomene ce caracterizează curgerea magnetohidrodinamică din canalele pompelor electromagnetice. În partea dedicată studiului pompării electromagnetice a sărurilor topite, teza evidențiază problemele specifice legate de generarea forțelor electromagnetice în fluide slab conductoare electric și oferă rezultate cu privire la aplicațiile unde pomparea electromagnetică a sărurilor topite poate fi eficientă. Cu ajutorul modelelor electromagnetice s-au obținut date importante despre influența numărului de poli electromagnetici și frecvența de alimentare asupra caracteristicii Presiune – Viteză a pompelor electromagnetice inelare de inducție. Au fost analizate fenomenul de ecranare creat de peretii metalici – cu repercursiuni negative asupra performanțelor pompelor, efectele de frânare exercitate la intrarea și la ieșirea din canalul de pompare și legătura dintre capacitatea de suprasarcină hidrodinamică și caracteristica Presiune – Viteză a pompelor de inducție. O secțiune specială a fost consacrată analizei dependenței de timp și a variației de la punct la punct a forței electromagnetice, precum și studiului neuniformităților mărimilor de natură electromagnetic în direcție azimutală în pompele inelare de inducție. În capitolul despre interacțiunea magnetohidrodinamică pe baza modelelor cuplate, se propun două modele ce cuplează electromagnetismul și curgerea fluidelor, unul realizat cu ajutorul unui singur software și al doilea realizat prin cuplarea a două software-uri diferite. Sunt prezentate avantajele modelelor cuplate din punctul de vedere al acurateței rezultatelor în comparație cu modelele electromagnetice …

Despite the scientific, technological and surgical improvements of the past 50 years organ dysfunction following elective paediatric cardiac surgery utilising cardiopulmonary bypass continues to account for increased complications, often leading to a protracted course in hospital with a longer stay in intensive care and the potential for irreversible organ damage long term. Furthermore, paediatric cardiac surgeons are routinely undertaking more complex operations with a shift from palliation to early correction. This has resulted in younger children being subjected to longer periods on the bypass machine with increased effects on vital organs. This thesis describes two clinical studies designed to further assess and characterise peri-operative cardiac, renal and pulmonary function in children undergoing elective cardiac repair at a tertiary referral centre in Scotland, UK. In the first instance a prospective, observational study was undertaken in forty-five children to examine the use of tissue Doppler imaging in the assessment of peri-operative cardiac function, its relationship to myocardial injury and clinical outcome. Tissue Doppler parameters were obtained using a Vivid 7 ultrasound scanner with a 7-MHz probe pre-operatively, on admission to paediatric intensive care and on day one. Myocardial injury was assessed using Troponin-I on the first post-operative day by a commercially available chemiluminescent immunoassay. In twenty children within this group peri-operative renal function was also investigated using standard estimates of glomerular filtration rate, namely creatinine clearance measured by the kinetic Jaffe method during the first and second twelve hour post-operative periods, in comparison to serum creatinine and the novel biomarker cystatin C. Routine plasma retained pre-operatively and on days 0, 1, 2 and 3 post-operatively was used to measure serum cystatin C and creatinine using a particle-enhanced nephelometric immunoassay and the Roche Creatinine Plus enzymatic assay respectively. The association between cystatin C and recorded perfusion parameters including bypass duration, pump flow, haematocrit, oxygen delivery and Troponin-I was investigated. Peri-operative pulmonary function was evaluated through a phase IV, randomised, double-blind, placebo controlled trial. In total, twenty four children were randomised to receive oral sildenafil or equivalent volume placebo four times the day before surgery. Blood samples were collected peri-operatively to measure serum cyclic guanosine monophosphate with a commercially available competitive enzyme immunoassay. Haemodynamic data and echocardiography were acquired at two and twenty four hours post-operatively including pulmonary vascular resistance index and bi-ventricular contractility. Post-operative oxygenation was also determined at the same time by oxygen delivery and oxygenation index. In Chapter 2, peri-operative cardiac function as assessed by tissue Doppler imaging was examined. The results of this study demonstrated that pre-operatively, bi-ventricular systolic function in the study group was reduced compared with normal controls, displaying a significant step-wise decrease with increasing complexity of lesion. This picture persisted post-operatively predominantly in the right ventricle and was significantly associated with the extent of myocardial injury. Impaired peri-operative left ventricular function correlated with clinical outcomes. In Chapter 3, peri-operative renal function as assessed by cystatin C and its association with parameters of perfusion was examined. The results of this study demonstrated that in comparison to serum creatinine, cystatin C had a superior correlation with glomerular filtration rate in the early post-operative period. An elevated level of this biomarker was significantly associated with bypass duration, minimum pump flow and post-operative myocardial injury. Haematocrit was not directly linked to renal dysfunction in this study although evidence of a critical dysoxic threshold within the kidney was suggested indirectly through oxygen delivery calculations. In Chapter 4, peri-operative pulmonary function and vascular reactivity in association with the pre-operative administration of oral sildenafil (0.5mg/kg, six hourly) was examined. The results of this trial demonstrated that compared to placebo, pre-operative sildenafil resulted in modest elevations of serum cyclic guanosine monophosphate, limited effects on pulmonary vascular resistance index, significant reductions in peri-operative bi-ventricular contractility, significant reductions in post-operative oxygen delivery and a trend for increasing ventilatory support. In summary, the current thesis has demonstrated that in children undergoing corrective cardiac surgery peri-operative bi-ventricular function can be accurately assessed by tissue Doppler imaging which to date has had limited use in this patient group. With regards to renal function, cystatin C was shown to be a better estimate of glomerular filtration rate and a more sensitive marker of early renal dysfunction in children after surgery. Furthermore, cystatin C identified a transient post-operative renal impairment, the magnitude of which was associated with duration of bypass, pump flow and myocardial injury. In relation to pulmonary function, this research identified that pre-operative administration of oral sildenafil to children undergoing cardiac surgery produced limited effects on pulmonary vascular resistance but was associated with reduced ventricular contractility and post-operative oxygenation raising significant concerns over its routine clinical use.

Many automotive systems are real-time systems, which means that not only correct operationsbut also appropriate timings are their main requirements. Considering the in uence that end-to-end delay might have on the performance of the systems, the calculation of it is of necessity.Abundant techniques have actually been proposed, and some of them have already been applied intopractical systems. In spite of this, some further work still needs to be done. The target of thisthesis is to evaluate and compare two end-to-end timing analysis methods from dierent aspectssuch as data age, consumption time, and then decide which method is a prior choice for end-to-end timing analysis. The experiments can be divided into three blocks, system generation andend-to-end delay calculation by two methods respectively. The experiments focus on two kinds ofperformance parameters, data age and the consumption time that these two methods cost duringtheir execution. By changing the system generating parameters like task number and periods, thechanges of performances of the two methods are analyzed. The performances of the two dierentmethods are also compared when they are applied into the same automotive systems. According tothe results of the experiments, the second method can calculate more accurate data age and consumeless time than the rst method does.