No description available.

No description available.

Dans l’analyse des émetteurs alpha et beta dans l’eau par scintillation liquide, la problématique de la discrimination des rayonnements se pose afin d’atteindre les limites de détection souhaitées. Dans le cas rare ou les énergies permettent une discrimination, nous avons mis en place un protocole d’analyse simultanée tritium/alpha sur des frottis. A l’aide d’une méthode a trois fenêtres il permet d’atteindre les limites de détection de 0,4 Bq/cm2 en tritium et de 0,04 Bq/cm2 en alpha.De façon générale, aucune distinction entre les spectres n’est possible et un ajustement du fond sous le pic alpha ne permet pas d’atteindre les limites de détection définies par les normes. Cependant le processus physique de scintillation permet une distinction des rayonnements, phénomène utilise par certains appareils, ceux-ci proposent donc le réglage par l’utilisateur d’un paramètre discriminant seuil. Nous avons développé un protocole de réglage permettant de reconstituer les spectres alpha et beta discrimines au mieux, rendant accessible une limite de détection de 0,03 Bq/L en alpha.Nous avons par ailleurs développé une approche innovante utilisant un détecteur en coïncidence dont les photomultiplicateurs sont connectes directement a une carte numérique d’acquisition. Chaque impulsion numérisée est ensuite traitée selon plusieurs critères simultanément, à la place des deux habituels. Aucun ne permet a lui seul d’obtenir une discrimination selon un seuil unique, mais la distribution des évènements dans chaque spectre est différente : un fenêtrage des évènements alpha permet d’atteindre une limite de détection de 0,2 Bq/L, quatre fois moindre que par une discrimination en énergie seule. / Analysis of water for alpha and beta emitters by liquid scintillation suffers from poor discrimination between the emissions and prevents reaching the lowest detection limits. In the rare cases where well separated energies permit discrimination, we can use a three-window protocol for simultaneous analysis of tritium and alphas of swipes that yields detection limits of 0.4 Bq/cm2 for tritium and 0.04 Bq/cm2 for alphas. In the general case, no distinction between the two radiations is possible. An adjustment of the background under the alpha peak does not allow reaching detection limits defined by the norms. However the physical process of scintillation offers users of certain models of apparatus to adjust a discrimination threshold that will separate the emissions. We have developed a protocol that reconstitutes spectra using independent settings that gives a detection limit for alphas of 0.03 Bq/L. We have also developed an innovative approach using a scintillation counter with its photomultipliers plugged directly into a fast analog-to-digital acquisition converter. Then each digitized pulse is simultaneously processed according to several criteria, instead of the usual two. No impulsion can be discriminated on the basis of a single threshold but the distribution of events in each spectrum is different: a window setting on the alphas permits attaining a detection limit of 0.2 Bq/L for alphas, four times lower than with a selection on energy alone.

No description available.

Il existe des algorithmes en meilleur d'abord efficace pour la résolution des jeux déterministes à deux joueurs et à deux issues.Nous proposons un cadre formel pour la représentation de tels algorithmes en meilleur d'abord.Le cadre est suffisamment général pour exprimer des algorithmes populaires tels Proof Number Search, Monte Carlo Tree Search, ainsi que l'algorithme Product Propagation.Nous montrons par ailleurs comment adapter ce cadre à deux situations plus générales: les jeux à deux-joueurs à plusieurs issues, et le problème de model checking en logique modale K.Cela donne lieu √† de nouveau algorithmes pour ces situations inspirés des méthodes Proof Number et Monte Carlo.La technique de l'élagage alpha-beta est cruciale dans les jeux à actions séquentielles.Nous proposons une extension de cette techniques aux stacked-matrix games, une généralisation des jeux à deux joueurs, à information parfaite et somme nulle qui permet des actions simultanées. / Efficient best-first search algorithms have been developed for deterministic two-player games with two-outcome.We present a formal framework to represent such best-first search algorithms.The framework is general enough to express popular algorithms such as Proof Number Search, Monte Carlo Tree Search, and the Product Propagation algorithm.We then show how a similar framework can be devised for two more general settings: two-player games with multiple outcomes, and the model checking problem in modal logic K.This gives rise to new Proof Number and Monte Carlo inspired search algorithms for these settings.Similarly, the alpha-beta pruning technique is known to be very important in games with sequential actions.We propose an extension of this technique for stacked-matrix games, a generalization of zero-sum perfect information two-player games that allows simultaneous moves.

<p>Att "smarta" brädspelande datorprogram har blivit mycket bättre under de senaste årtiondena har väl knappast kunnat undgå någon. Med brädspel menar jag spel såsom Go, Othello, Backgammon och Schack. Idag spelar program, som körs på en reguljär PC, bättre än de flesta människor. Vad är det som gör dessa program så bra? Hur kan man lära en dator att spela ett så pass komplext spel som Othello på en sådan nivå att ingen människa har en chans att vinna? I detta examensarbete kommer jag att försöka förklara mekanismerna bakom ett toppspelande Othelloprogram. Jag har dessutom implementerat ett eget Othellospelande program som jag använt som testapplikation för att prova olika sökmetoder, metoder för att öka exekveringshastigheten och tekniker för att öka spelskickligheten. Jag kommer att presentera empiriska data där jag utvärderar och jämför flera andra program med mitt eget.</p>

Alpha-Beta transition in quartz is studied using the Raman scattering. The Raman frequencies of some lattice modes are analyzed at various temperatures close to the alpha beta transition in quartz. For this analysis, the experimental data from the literature is used and the soft mode behavior of those Raman phonons is investigated . On the basis of the predictions of some models, the temperature dependencies for the Raman frequencies of the lattice modes which move towards zero (soft mode) and their bandwidths close to the transition temperature Tc are explained for the alpha-beta transition in quartz. In addition, by using the experimental volume data from literature, calculation of the temperature dependence of the Raman frequencies through the Gr&uuml / neisen parameter have been studied near the phase transition.

Protein phosphorylation is a post translational modification of proteins in which a serine, a threonine or a tyrosine residue is phosphorylated by an enzyme, kinase. Phosphorylation of proteins is a reversible and very important regulatory mechanism that occurs in both prokaryotes and eukaryotes. Phosphorylation turns many protein enzymes on and off, preventing or causing many diseases such as diabetes, cancer and rheumatoid arthritis. The phosphorylation on tyrosine residues of proteins is essential for transmission of signals for cell growth, proliferation and differentiation. Protein tyrosine phosphatases (PTPs) in concert with protein tyrosine kinases (PTKs) regulate many signal transduction pathways by controlling the degree of phosphorylation of tyrosine residues within the protein. While the roles and mechanisms of protein tyrosine kinases are well documented, our present understanding of protein tyrosine phosphatases is very limited. In this regard we still have much more to learn about PTPs. Here we propose the design and synthesis of novel protein tyrosine phosphatase mimetics and their activity against tyrosine phosphatases. Chapter two describes the synthesis of 2-aminopyrimidine chlorides, sulfonamides and the sequence of reactions to make its amino acid analog. Chapter three describes the synthesis of α-aryl, α,β-epoxy carboxylates, phosphonates and their biological activity against tyrosine phosphatases. These compounds could be very helpful in significantly improving the current understandings about the roles and mechanisms of the PTPs. These proposed tyrosine phosphatase inhibitors are believed to work effectively in treating the diseases by modulating the phosphorylation in signal transductions pathways. Chapter four describes the design and the synthesis of Peptide Nucleic Acids (PNAs) both standard as well as hybrid PNAs with novel cysteine based monomers that are aimed to increase the cellular uptake by introducing positively charged or amphipathic species attached to cysteine thiol functional group.

Thesis (Ph. D.)--University of Washington, 1999. / Vita. Includes bibliographical references (leaves 112-132).

Att "smarta" brädspelande datorprogram har blivit mycket bättre under de senaste årtiondena har väl knappast kunnat undgå någon. Med brädspel menar jag spel såsom Go, Othello, Backgammon och Schack. Idag spelar program, som körs på en reguljär PC, bättre än de flesta människor. Vad är det som gör dessa program så bra? Hur kan man lära en dator att spela ett så pass komplext spel som Othello på en sådan nivå att ingen människa har en chans att vinna? I detta examensarbete kommer jag att försöka förklara mekanismerna bakom ett toppspelande Othelloprogram. Jag har dessutom implementerat ett eget Othellospelande program som jag använt som testapplikation för att prova olika sökmetoder, metoder för att öka exekveringshastigheten och tekniker för att öka spelskickligheten. Jag kommer att presentera empiriska data där jag utvärderar och jämför flera andra program med mitt eget.