This thesis is part of a larger qualification effortperformed at Westinghouse Electric Sweden AB of the PHOENIX5 latticephysics code. The aim of the thesis is to validate PHOENIX5 withregards to cold criticality tests performed at the Toshiba NCAfacility in 2010-2011. For this, 26 different models were built torepresent the experiments performed by Toshiba in PHOENIX5. As anindependent reference, models were also built for the probabilisticMonte Carlo code SERPENT. The parameters examined in this thesis arethe criticality of the system, as well as the pin fission rates forselected experiments. Two different PHOENIX5 libraries were utilized,along with a HELIOS library. The results show that there is a Kinf trend between the differentlibraries. Furthermore, a void trend was found. This void trend waspresent for all models, including the SERPENT models. Pin fissionrate predictions give results close to those of the experiments forboth PHOENIX5 libraries. The system also proved sensitive to meshingchanges, as well as for the chosen water reflector width.

L’opinion commune pense généralement que les écrits de l’Empereur Julien n’ont guère irrigué la littérature grecque des siècles suivants. Du côté païen, les philosophes néoplatoniciens, auraient presque complètement ignoré son œuvre parce qu’ils n’y reconnaissaient pas vraiment de dimension philosophique. Quant aux écrivains chrétiens, surtout animés d’intentions polémiques contre le paganisme et l’Apostat, ils auraient fait peu de cas des écrits de Julien, peu cités et déformés. Une analyse du mode de citation des œuvres et un repérage systématique des grands concepts de Julien permet de nuancer et d’infirmer ces vues. En effet, des écrivains chrétiens comme Grégoire de Nazianze et Jean Chrysostome citent de nombreux termes empruntés au vocabulaire philosophico-religieux de Julien et les historiens ecclésiastiques comme Socrate de Constantinople et Sozomène mentionnent souvent de longs extraits de textes entiers, notamment les lettres. L’attitude des auteurs païens est plus ambiguë, oscillant entre un éloge de la valeur littéraire de ses écrits et un silence quasi absolu, lui-même ambigu car souvent associé à un double langage tendant à rendre un hommage appuyé à la théologie solaire et à l’antichristianisme de Julien. On peut suivre le fil de cette tradition polémique depuis Libanios, Ammien Marcellin et Saloustios jusqu’au philosophe Ammonios d’Alexandrie. / The critics have usually thought that Emperor Julian's books have not deeply influenced the literature of Late Antiquity. On the one hand, it would seem that pagan writers, especially neoplatonic philosophers, have completely ignored his works because they denied them any philosophical significance. On the other hand, Christian writers, obsessed by their polemic against paganism and the Apostate, would have paid little attention to his writings, using very few quotations and above all misquoting him. However, if we research systematically how Julian’s works and the main points of his thought appear in this literature, we can challenge such a statement. In fact, Christian writers like Gregory of Nazianzenus and John Chrysostom quote many words from Julian's philosophical and theological vocabulary and church historians like Socrates and Sozomen quote many large extracts of Julian, especially his letters. We can’t find the same phenomenon with pagan writers. Their attitude towards Julian is ambiguous: behind a general eulogy or a complete silence, we can see that several of them, like Libanius, Ammianus, Sallustius and Ammonius of Alexandria tried to continue his thought, especially his devotion to King Helios and his polemic against Christianity, using language with double meaning.

No description available.

The coarse mesh radiation transport (COMET) code uses response functions to solve the neutron transport equation. Most nuclear codes used today have a very steep learning curve; COMET is no exception. To ease the user's onus of learning how to create correctly formatted COMET input-files, a graphical user interface (GUI) was created. The GUI allows the user to select values for all the relevant variables while simultaneously minimizing the errors a typical new user would make. To this end, the GUI creates all of the input files required to run COMET. The GUI also provides a visualization tool that the user may use to check the problem geometry before running COMET. The GUI is also responsible for post-processing the COMET output for visualization with TecPlot. In addition to the GUI, multi-group cross section libraries were generated as part of the MHTGR-350 (Modular High Temperature Gas Reactor) benchmark problem under development at Georgia Tech. This project aims to couple COMET with a thermal hydraulics code to best model the true physics of the reactor design. In order for this goal to be actualized, six-group cross sections were generated over the operational temperature range of the MHTGR using the current coupling and collision probability code HELIOS.

Les cellules souches hématopoïétiques (CSH) sont à l’origine de l’ensemble des cellules hématopoïétiques, mais les mécanismes responsables de leurs réponses au stress ne sont que partiellement compris. J’ai étudié le rôle du facteur de transcription Helios dans les CSH, dans lesquelles il est fortement exprimé. J’ai trouvé que les CSH de souris nulles pour Helios (He-/-) possèdent un plus fort potentiel de reconstitution que les CSH WT dans des expériences de transplantations en série. De manière frappante, les souris âgées de 2 ans possèdent 8 fois plus de CSH fonctionnelles par rapport aux souris vieilles WT. De plus, le pool de CSH de long terme de souris He-/- vieilles ressemblent aux CSH WT jeunes en termes de phénotype et de fréquences. Les CSH He-/- vieilles présentent une dérégulation de gènes impliqués dans le vieillissement. De plus,les CSH He-/- jeunes sous-expriment des gènes codant des protéines impliquées dans la réparationde l’ADN ainsi que dans la voie p53. Quand les CSH He-/- et WT sont traitées avec différents agents radiomimétiques qui induisent des cassures simple et double brins à l’ADN, tels que la néocarzinostatine, la camptothécine ou l’étoposide, l’entrée en apoptose, en sénescence et l’arrêt de la prolifération des CSH He-/- sont altérées. Ce phénotype est accompagné d’une faible induction des gènes cibles de p53 et d’une altération du dégagement des foyers gammaH2AX. De plus, j’ai montré que Helios agit en synergie avec p53 pour réguler les réponses aux dommages à l’ADN des CSH. Mes résultats suggèrent qu’en synergie avec p53, Helios contrôle le vieillissement des CSH en prévenant l’accumulation des dommages de l’ADN des CSH. / Hematopoietic stem cells (HSCs) give rise to all blood cell lineages but the mechanisms responsible of HSCs responses to stress remain partially understood. I studied the role of the transcription factor Helios in HSCs, where Helios is highly and specifically expressed. I found that HSCs from young Helios null mice (He-/-) reconstitute the hematopoietic system of irradiated recipient mice similarly to HSCs from WT mice in primary transplantations, but out-perform WT cells in secondary and tertiary transplantations. Strikingly, HSCs from 2-year-old He-/- mice had 8-fold higher reconstitution potential than old WT HSCs in primary transplantations. Moreover, the pool of long-term HSCs in old He-/- mice resembles that of young WT animals in both phenotype and frequency. HSCs from old He-/- mice present a down regulation of genes involved in aging. Further, young He-/- HSCs express reduced mRNA levels of genes encoding DNA repair proteins as well as those associated with thep53 pathway. When He-/- and WT HSCs were subjected to DNA damage by different agents like neocarzinostatin, camptothecin, or etoposide, DNA damage-induced apoptosis, senescence and cell cycle arrest were significantly impaired in He-/- HSCs. This phenotype was accompanied by a poor induction of p53 target genes and impaired clearance of gammaH2AX foci. Furthermore, I found that Helios synergies with p53 to regulate the DNA damage responses of HSCs. My results suggest that,in synergy with p53, Helios controls HSC aging by preventing the accumulation of DNA damage in these cells.

Thesis (MCom (Communication Management))-- University of Pretoria, 2008. / Abstract in English. Includes bibliographical references. Available on the Internet via the World Wide Web.

Les facteurs de transcription Eos et Helios ont été décrits comme étant des modulateurs des fonctions des cellules T régulatrices (Treg). Nos résultats suggèrent qu’Eos et Helios ne sont pas nécessaires, ni pour la différenciation, ni pour les principales fonctions des cellules Treg CD4+. Cependant, les cellules Helios-/- présentent une meilleure activité suppressive et à un profil transcriptomique de cellules Treg activées. Pour tester si Eos et Helios coopèrent pour réguler les fonctions des cellules Treg, nous avons analysé les souris doubles mutantes. Nos découvertes indiquent que la perte combinée d’Eos et d’Helios n’a pas d’effet sur la biologie des cellules Treg. De plus, nous avons montré qu’Eos et Helios sont induits dans les cellules Treg CD8+. Néanmoins, seule la perte d’Helios ou celle combinée d’Eos et d’Helios affectent leur différenciation. Tous ces résultats suggèrent donc qu’Eos et Helios ne sont pas requis pour réguler les fonctions essentielles des cellules Treg. / The transcription factors Eos and Helios have been described as modulators of regulatory T cell (Treg) functions. Our results suggest that they are not necessary for the differentiation and essential functions of CD4+ Treg cells. However, Helios-/- cells present a superior suppressive activity and a transcriptional profile of activated Treg cells. To test if Eos and Helios can cooperate to regulate Treg cell functions, we then analyzed double null mice. Our findings indicate that loss of both Eos and Helios has no effect on Treg cell biology during homeostasis. In addition, we showed that Eos and Helios are induced in CD8+ Treg cells. However, only loss of Helios, or both Helios and Eos, affect their differentiation. Altogether, these results suggest that Eos and Helios are not required regulate essential CD4+ Treg cell functions, but the absence of Helios may have an impact on their level of activation. Finally, Helios and Eos may play role of in the CD8+ Treg cell compartment.

This thesis presents a whole-core benchmark of the European Pressurized Reactor (EPR) using multiple transport methods. The core specifications were taken directly from the Final Safety Analysis Report (FSAR) submitted to the Nuclear Regulatory Commission (NRC) and the reactor was modeled in a stylized manner while maintaining full heterogeneity at the pin and assembly level. The geometry and material specifications are given as well as problem-specific cross sections for 2, 4, and 8 energy group calculations. Cross sections were generated using HELIOS, a lattice depletion code based on the Collision Probability Method (CPM). The multi-group cross sections were utilized in the reference calculation, COMET calculation, and response function generation. The reference solution was obtained via an MCNP model identical to the one implemented in COMET. Specific steps towards constructing and running a COMET calculation are outlined. Detailed results including assembly eigenvalues, core eigenvalues, and pin fission densities are presented.

Main goal of this document is to make reader aware of economical aspects of the information system design with regards to various types of organizations. It focuses on different approaches of organizations to the information system depending on expected function of IT within their business objectives. IS SAP and IS Helios SW products were used in order to present benchmark of economical figures of different information systems.

A lattice physics code is a vital tool, forming a base of reactor coreanalysis. It enables the neutronic properties of the fuel assembly to becalculated and generates a proper set of data to be used by a 3-D full coresimulator. Due to advancement and complexity of modern Boiling WaterReactor assembly designs, a new deterministic lattice physics codeis being developed at Westinghouse Sweden AB, namely PHOENIX5.Each time a new code is written, its methodology of solving the neutrontransport equation, has to be validated to make sure it providesreliable output. In a wake of preparation for PHOENIX5 release andconsecutive validation efforts, a set of reference Monte Carlo calculationswas prepared, using the code Serpent. A depletion calculation with achosen type of branch cases was conducted. Methods implemented inPHOENIX5 are based on the Current Coupling Collision Probabilitymethod used in older versions of the code HELIOS. Therefore, a comparisonbetween reference Monte Carlo simulations and HELIOS 1.8.1is made, in order to discover problems inherent to the said method ofsolving the neutron transport equation. A special care should be givenduring PHOENIX5 validation, to issues highlighted in this work.Discrepancies in results of Serpent and HELIOS are attributed mostlyto disparities in the basic nuclear data used by the codes, as well as arange of approximations and corrections adopted by the deterministiccode.Serpent and HELIOS showed a good agreement in a typical voidrange (up to 90 % void) and ‘less’ challenging branches (coolant void,fuel temperature and spacer grid branches). More significant discrepanciesappeared for extreme cases with a very high void and control rodpresence (k1 differences as high as 1000 pcm) and rather pronouncedconcentrations of the natural boron dissolved in coolant (absolute differencesroughly at a level of 900 pcm). The issues do not seem to stemsolely from discrepancies in the nuclear data libraries used by Serpentand HELIOS.Moreover, a coolant void bias was consistently found in the resultsof branch calculation at changing coolant void. This confirms the analogousphenomenon found in previous studies of the CCCP based deterministiccodes. It most probably stems from the assumptions used bythe method while tackling the neutron transport equation, such as theflat source approximation, the isotropic scattering assumption and thetransport correction. An alternative transport correction approximationis proposed to alleviate this issue.