My dissertation focuses on changes in health-related behavior in react to information-based intervention. The first chapter analyzes the results of a field experiment to investigate the effects of comparative information on the daily number of steps taken of adults. The second chapter further explores the effects using qualitative analysis. The third chapter intends to offer explanations in the mechanisms of the results from the first chapter. My first chapter uncovers how patterns in the daily number of steps of adults are affected by information that compares one with unknown peers. I conducted a field experiment that used fitness trackers to collect daily and minute-by-minute data on the total number of steps an individual takes in a day. Participants were randomized into a group that was provided with comparison information and a group that did not receive such information. I examined whether individuals in the two groups behaved differently during and after the intervention period. I find no clear evidence of an aggregate impact of social norms on the daily number of steps taken. However, I find individuals who are not overweight or nor married or cohabiting are more likely to be influenced by social norms. Greater treatment effects are found among individuals whose number of steps that are at the tails of the distribution curve. My second chapter reports the results of the textual data from the survey in the field experiment. I present dominant themes that emerged from answers to the open-ended essay questions in the survey. The results support that health concern, body image, appearance, psychological factors, peers and friends are major motives for being physically active. For participation in the study specifically, text messages that contain comparative information produced some improvement of the exercise level. However, participants also requested more interactions with peers, additional information provision, rewards for reaching goals. The results imply external incentives play a smaller role in promoting daily number of steps. In the third chapter, I conduct a survey experimentation to test the effectiveness of informing descriptive social norms and types of text messages in predictions about health-related behaviors. First, I investigate if errors in beliefs about activity levels exist and I find no evidence of over- or under-confidence in one’s own activity levels. Further analysis provide preliminary evidence of negative effects of informedness in predictions about one’s own behavior. However, the intention-to-treat effects of comparative information are unclear. The data provide evidence in favor of the correlation between first-order personal beliefs, not higher-order normative beliefs, in predicting an increase number of steps taken in response to intervention with text messages.

Optimization of electronic warfare (EW) receiver scan strategies is critical to improving the probability of surviving military missions in hostile environments. The problem is that the limited understanding of how dynamic variations in radar and EW receiver characteristics has influenced the response time to detect enemy threats. The dependent variable was the EW receiver response time and the 4 independent variables were EW receiver revisit interval, EW receiver dwell time, radar scan time, and radar illumination time. Previous researchers have not explained how dynamic variations of independent variables affected response time. The purpose of this experimental study was to develop a model to understand how dynamic variations of the independent variables influenced response time. Queuing theory provided the theoretical foundation for the study using Little's formula to determine the ideal EW receiver revisit interval as it states the mathematical relationship among the variables. Findings from a simulation that produced 17,000 data points indicated that Little's formula was valid for use in EW receivers. Findings also demonstrated that variation of the independent variables had a small but statistically significant effect on the average response time. The most significant finding was the sensitivity in the variance of response time given minor differences of the test conditions, which can lead to unexpectedly long response times. Military users and designers of EW systems benefit most from this study by optimizing system response time, thus improving survivability. Additionally, this research demonstrated a method that may improve EW product development times and reduce the cost to taxpayers through more efficient test and evaluation techniques.

The purpose of this online cross-sectional study was to identify cannabis user profiles by administration method and examine how differential cannabis policies influence intentions among young adults. Participants were assigned randomly to one of three hypothetical cannabis policy conditions (recreationally legal; medically legal; illegal). Within conditions, participants completed measures regarding cannabis use, including administration methods, cannabis attitudes, norms, perceived behavioral control, self-efficacy, and intentions. Latent class analysis (LCA) was used to determine sub-groups of past 30-day cannabis users by administration method followed by sub-group comparisons. Condition effects on intentions and associated variables were examined using ANCOVA. Four classes (Low-Blunt, Low-Bong, Mod-Poly, High-Poly) differing in demographics and tobacco use were identified. Recreationally and medically legal policy conditions resulted in more favorable cannabis attitudes, higher selfefficacy, and higher intentions to use compared to the illegal policy condition. Results inform cannabis intervention efforts and longitudinal research on the effects of cannabis policy changes.

Leptogenesis is a class of scenarios where the baryon asymmetry of the Universe is produced from a lepton asymmetry generated in the decays of a heavy sterile neutrino. We explain the motivation for<br />leptogenesis. We review the basic mechanism, and describe subclasses of models. We then focus on recent developments in the understanding of leptogenesis: finite temperature effects, spectator processes, and in particular the significance of flavour physics.

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Le travail présenté dans cette thèse a été réalisé grâce aux données enregistrées de 1991 à 1994 par le le détecteur DELPHI au LEP. Il porte sur la détermination du paramètre libre IVcbl du Modèle Standard de l'interaction électrofaible à partir de la désintégration semileptonique $\bar{B}^0_d -> D*^{+}l-\nu_l$. Une deuxième analyse sur la production d'états charmés orbitalement excités dans les désintégrations semileptoniques des mésons B est aussi présentée. La mesure de IVcb/ repose sur la détermination précise du spectre en moment transféré $q^2 = (m_b - m_D*)^2$ des événements reconstruits de manière exclusive. L'ajustement de ce spectre par l'expression théorique donnée par la théorie effective des quarks lourds (HQET) permet d'obtenir la valeur de IVcb| vec une incertitude théorique inférieure à 4 %. L'exposé de ce travail commence par un présentation du rôle de l'élément de matrice lVcbl et des outils théoriques nécessaires à sa mesure. Le dispositif expérimental utilisé est ensuite décrit. Les différentes étapes de l'analyse sont détaillées: sélection des événements, étude des bruits de fond, mesure du rapport d'embranchement Br($\bar{B}^0_d -> D*^{+}l-\nu_l$ qui est l'étape préliminaire à la mesure de |Vcb| . La mise au point des estimateurs du moment transf4ré est ensuite ex~oséeL. a détermination du spectre en moment transféré des événements -+ DS+l-fi sélectionnés et son ajustement conduisent finalement à la mesure de /VcbI . Les résultats obtenus sont: Br($\bar{B}^0 -> D*^{+}l-\nu_l) = (5,17$\pm 0,49(stat) \pm 0,71(syst))% $|V_{cb}| = (38,7\pm 3,4(stat) \pm 2,9(syst) \pm 1,2(th)) x 10^{-3}$ Ces mesures sont en bon accord avec les résultats obtenus par d'autres collaborations auprès du LEP ou des usines à mésons B (CESR, DESY). L'analyse concernant la recherche d'états charmés excités orbitalement dans les désintégrations semileptoniques des B a permis de mesurer le rapport d'enibranchement Br(b -> $D^0_{J}lX) x Br(D^0_J -> D*^{+}\pi-) = (6.0^{+1,7}_{-1,5}(stat) \pm 0,8(syst))) x 10^{-3}$ où $D^0_J$ correspond à la somme des deux états charmés étroits $D^0_1$ et $D*^0_2 . Cette mesure, quoique statistiquement peu précise indique la présence non négligeable d'excitations orbitales charmées dans les désintégrations sernilcptoniques des B.

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