The intensity dependent refractive index change of a medium is frequently described in terms of the product n₂ · I where n₂ is the nonlinear refractive index and I the light intensity. The nonlinear refractive index is often treated as constant which is a reasonable assumption if the light interacts only with bound electrons. In the case of carbon disulfide (CS₂) however, nuclear motions contribute to n₂. These motions occur on the sub picosecond time scale and thus become especially relevant for ultrashort laser pulses. The neat liquid CS₂ is studied because it exhibits a large nonlinear refractive index in comparison to other liquids. Therefore, it is employed in optical switching, optical limiting, and beam filamentation applications. This thesis presents effective n₂ values for Gaussian shaped linearly polarized pulses with central wavelength at [lambda]= 700nm. A theoretical model describing the time evolution of the material response is applied to distinguish between the instantaneous electronic, the ultrafast nuclear and the slow nuclear origins of the nonlinear refractive index. Moreover, the tensor nature of the material response function is studied by means of circularly polarized light. The relative magnitudes of bound electronic and nuclear contributions to n₂ are experimentally determined. Eventually, the dispersion of the instantaneous electronic response is measured in the spectral range between 390nm and 1064nm.

This dissertation describes the development of novel techniques for characterization of nonlinear properties of materials. The dissertation is divided into two parts, a background and theory section and a technique development section. In the background and theory section we explain the origins of the nonlinear optical response of materials across many different spatial and temporal scales. The mechanisms that we are most interested in are the electronic nuclear and reorientational responses, which occur on the range of sub-femtosecond to several picoseconds. The electronic mechanism is due to the electrons of a material experiencing a non-parabolic potential well due a strong electric field and occurs on the sub-femtosecond timescale. The nuclear or vibrational effect results from the motion of the nuclei of the atoms and typically occurs on the order of a few hundred femtoseconds. Finally the reorientational nonlinearity is due to the alignment of the molecule to the electric field, which alters the polarizability of the molecule and typically occurs on the scale of a few picoseconds. There are other mechanisms can induce nonlinear optical effects such as thermal effects and electrostriction, but these effects typically occur on much larger timescales than we are interested in, and hence will not be a major focus of this dissertation. In the nonlinear characterization techniques section, we describe previous research into the field of nonlinear optical characterization techniques, describing the techniques used to characterize the nonlinear properties of materials, their applications and limitations. We will trace the development of two recently developed techniques for nonlinear spectroscopy − the Dual Arm iii Z-Scan and the Beam Deflection techniques. The Dual Arm Z-Scan technique is an enhancement of the standard Z-Scan technique that allows for the measurement of small nonlinear signals in the presence of large background signals. This technique allows for the measurement of materials under certain conditions not previously measureable using the standard Z-Scan technique, such materials with low damage thresholds, poor solubility and thin films. In addition to the Dual Arm Z-Scan, we have developed a new method for characterizing nonlinear refraction, the Beam Deflection technique, which is a variation of the photothermal beam deflection technique previously used to measure very weak absorption signals. This technique offers relative ease of use, the ability to measure the absolute magnitude and sign of both the real and imaginary parts of � (3) simultaneously with high sensitivity. We fully develop the theory for materials with instantaneous and non-instantaneous nonlinearities, with nonlinear absorption and group velocity mismatch. We also demonstrate the power of this technique to separate the isotropic and reorientational contributions of liquids by examining the temporal response and polarization dependences. Lastly, we summarize our conclusions and describe two promising future research directions that would benefit from the Dual Arm Z-Scan and Beam Deflection techniques

This research examines how Generation Z (individuals born between 1997 and 2012) is perceived to impact the construct of societal challenges and organisational changes within the context of Western Europe. To explore their impact, the research aims to investigate their perceived role in shaping societal perspectives and organisational responses. The study is guided by Mannheim's socio-historical theory, considering shared emotional orientations, motivations, considering limitations as a result of human development. Purposive sampling was employed to select participants with specialised knowledge of Generation Z's impact. Semi-structured interviews were conducted with seven participants, including Generation Z individuals, a sociology professor, an analyst, a youth worker, an HR professional, and individuals experienced with Generation Z-related issues. Reflexivity was applied to acknowledge the researcher's potential biases due to personal context as a Gen Z member. Thematic analysis was used to extract key themes from the interview data. The study contributes to understanding how Generation Z's socio-historical context shapes their perceptions, motivations, and actions, influencing societal challenges and organisational changes. It proposes a model connecting their context to expectations and actions. The research suggests that future studies should test the theoretical framework and investigate behaviour prediction based on widespread data. The study reveals that Generation Z's impact on society and organisations stems from their emphasis on authenticity, demand for transparency, and pursuit of purpose-driven approaches. They mobilise through digital skills, transforming personal concerns into collective activism, and their integration into organisations depends on alignment with values like transparency, social responsibility, and work-life balance.

Mémoire numérisé par la Direction des bibliothèques de l'Université de Montréal.

Hadronic collisions at the LHC at CERN probe particle interactions at the highest energy scale of any experiment to date. We present a research program measuring Rjet = &sigmaWBR(W&rarr&mu&nu) / (&sigmaZBR(Z&rarr&mu&mu)) as a function of a number of hadronic variables. The measurements are performed with the ATLAS detector at the LHC, using the 2011 data set, consisting of 4.64 fb-1 of pp collisions at a center of mass energy of 7 TeV. This measurement is a robust way to test the Standard Model and the modeling of perturbative QCD, and is sensitive to a wide variety of possible new physics in events with high jet ET, including some variations of Supersymmetry. By taking the ratio of W/Z production, a large number of systematic uncertainties cancel, including those associated with luminosity, jet energy scale and resolution, and many theoretical uncertainties. The measurement of Rjet is performed as a function of the pT and rapidity of the 1st-4th leading jet, ST, HT, and a number of dijet variables, including invariant mass and angular separations. The measurements are compared with NLO theoretical predictions from Blackhat+Sherpa, as well as using leading order simulations from Alpgen and Sherpa. Over most of the kinematic phase-space, there is good agreement between the data and theoretical predictions. There is a significant deviation for exactly one selected jet above 30 GeV, where Blackhat+Sherpa over-estimates the ratio Rjet by 12%.

Generation Z, personer födda mellan åren 1997-2012, är unika i deras egenskap av att vara den första generationen digital natives, det vill säga med liten eller ingen erfarenhet av ett liv utan internet. Ytterligare en unik identifikationsmarkör som lyfts fram hos generationen är deras egenartade humor, som beskrivs som abstrakt, oförståelig och intern. Internet skapar en global arena för generationen att dela denna humor. En central plattform där detta sker är Tikok. Tidigare forskning har teoretiserat om att Generation Z använder humor för att stärka den kollektiva identiteten, utifrån analyser av det humoristiska uttrycket memes. Vi avser med denna studie att skapa en bredare förståelse för denna obegripliga humorn i helhet med syftet att undersöka om den kan tänkas ha en betydelse för det kollektiva identitetsskapandet. Studien utgår ifrån en fenomenologisk ansats där vi avser att undersöka Gen Zs upplevelse av humoristiskt innehåll på Tiktok. Detta gjordes genom tio intervjuer. Med hjälp av Blumers interaktionistiska perspektiv, såväl som Goffmans teori om inramning kunde vi synliggöra att humorn är konstruerad kring komponenterna snabbhet, autenticitet, självdistans, originalitet och chockfaktor, samt att det finns primärt fyra olika typer av humor som upplevs roligt: dum-, observerande-, ironisk- och hånfull humor. Med hjälp av Jenkins och Tajfels teori om kollektiv identitetsskapande kunde vi synliggöra hur konstruktionen av humorn fyllde en central roll i att stärka den kollektiva identiteten på flera olika sätt. Således har vi kunnat synliggöra vad som upplevs roligt av Generation Z och vilken betydelse detta har för att stärka den kollektiva identiteten.

Indiana University-Purdue University Indianapolis (IUPUI) / Since the COVID-19 pandemic unexpectedly hit the world, the tourism industry has been impacted in every conceivable area. Environmental issues are recognized and considered essential to solve especially in the tourism industry. It is unavoidable that tourists bring both positive and negative impacts to a destination. Meanwhile, the tourism industry is eager to return to its pre-pandemic tourist numbers and levels of spending that traveler previously engaged in. The young generations, specifically Gen Y and Z, play an important role in the tourism market, and they often embody a mindset that takes into consideration issues of sustainability. However, they are not as active as expected in practicing sustainable travel behaviors. Sustainable tourism development and "green" travel practices are becoming increasingly necessary. The main purpose of this study is to identify the gaps between Gen Y and Z's intentions and their behaviors regarding sustainable travel. This study developed and tested a conceptual framework to understand this dynamic. This study identified two gaps: (a) the behavior-intention gap, which exists between Gen Y & Z's intentions and their behaviors in sustainable travel, and (b) daily life and sustainable travel gap, which is the gap between individuals’ daily sustainable habits and sustainable travel behaviors. The results of quantitative study indicated the factors contributed to the gaps included: (1) individuals who have bachelor’s degrees are more likely to conduct sustainable travel behaviors; (2) individuals who have daily sustainable habits; (3) individuals who have higher perceived consumer effectiveness. The implications of the study provide suggestions for destinations to promote sustainable travel and ways to encourage more sustainable traveling choices by travelers.

I takt med att internet växer sig större och större blir influencers en del av vardagen för många unga och de inriktar sig på många olika områden. Syftet med denna studie var att undersöka hur Gen Z upplever att deras investeringsbeslut kan bli påverkade av finansiella influencers, även kallat finfluencers. Gen Z valdes specifikt eftersom tidigare forskning visade att generationen har vissa specifika karaktärsdrag som påverkar deras beteende på sociala medier och som konsumenter. Med utgång i the Theory of Planned Behavior (TPB) utfördes semistrukturerade intervjuer med 12 respondenter som tillhörde Gen Z och hade en disponibel inkomst. Intervjusvaren analyserades sedan genom tematisk analys för att skapa en helhetssyn över hur beteendet kan påverkas. Resultaten från studien visar hur finfluencers kan påverka individer ur Gen Z på olika sätt. Exempelvis kan trovärdigheten hos en finfluencers budskap förstärkas genom att denne har akademisk bakgrund inom ekonomi eller kan presentera tidigare positiva resultat på aktiemarknaden. Det fanns delade meningar om huruvida individer skulle interagera med en finfluencer av sociala skäl men det framgick att individer som saknar kunskaper gällande investeringar löper större risk att bli påverkade av finfluencers. / With the internet growing and growing, influencers have become part of everyday life for youths and they focus on many different areas. The purpose of this study was to examine how Gen Z experiences the influence financial influencers, also known as finfluencers, could have on their investment decisions. Gen Z was chosen because previous research suggests that the generation has certain characteristics that affect their behavior on social media and as consumers. Using the Theory of Planned Behavior (TPB) as a framework, semi structured interviews were held with 12 respondents from Gen Z who also had a disposable income. The answers were analyzed using thematic analysis to create a holistic view of how the behavior can be affected. The results show that finfluencers can affect individuals belonging to Gen Z in different ways. Credibility of influencers can be improved by having an academic degree or being able to present positive results from earlier investment activities. There were differing opinions regarding whether individuals would interact with a finfluencer for social reasons. However, the interviews showed that individuals without relevant knowledge are more at risk of being influenced.

Background: Consumers of Gen Z are facing a reality of high inflation. With their unique characteristics and strong attitudes towards sustainability and environmental concern, this thesis is examining how their sustainable consumption is affected by inflation. Purpose: The purpose of this study is to examine the impact of inflation on the sustainable consumption of Generation z.  Method: A paradigm of interpretivism and abductive reasoning is used in the research and a multiple case study was conducted using semi-structured interviews.  Conclusion: Consumers of Gen Z are having a difficult time purchasing sustainable products because of inflation. Sustainable consumption has become difficult to maintain due to having less funds among Gen Z. As a result, Gen z consumers changed their consumption to less- costly and more sustainable alternative in order to adapt to the economic situation.   Despite inflation, our research has shown Gen Z consumers are still dedicated to the issue of sustainability and environment.

COVID-19 was a pandemic that has impacted the world in various ways and forced everyone to quarantine within the confounds of their homes. As studies investigated the effects of the pandemic, it was found that undergraduate students faced severe emotional and psychological difficulties being “at-risk” for greater psychological distress (Mayorga et al., 2021). Undergraduate students are currently made up of Generation Z individuals who are born from 1995 to 2010 (Ang et al., 2021). The present study investigates the relationship between mental health and generational cultural attitudes to explore whether there is a correlation between the stressors from COVID and generation Z’s cultural attitudes. A hypothesis is that generation z college students with more mental health issues due to COVID stressors will be more collectivist and the other is that Generation Z college students are more likely to experience more distress from COVID stressors than previous generations. Participants were given an online survey with the Individualism and Collectivism Scale (Triandis & Gelfand, 1998), Beck’s Depression Inventory-II (Beck et al., 1996), State-Trait Anxiety Inventory (Spielberger, 1983), and the Covid Stress Scale (Taylor et al., 2020). Data collection includes 183 undergraduate students from the University of Central Florida. Pearson correlations were conducted between depression, anxiety, and COVID stress. Also, a Pearson correlation was also made between individualism, collectivism, and COVID stress. Lastly, a paired sample t-test was conducted to compare the means between individualism and collectivism. Overall, results did not show support for the first hypothesis because although there was a significant correlation between depression, anxiety, and COVID stress, it cannot be told how much COVID stress affected mental health. Additionally, there was no significant correlation between collectivism or individualism and COVID stress, indicating that cultural attitudes did not predict the level of COVID distress. However, results did find that students were statistically more collectivistic than individualistic, which supports a part of my hypothesis. Understanding cohort and generational differences in emotional response to the COVID-19 pandemic will help in recognizing and assisting these groups. This would demonstrate a difference in emotional response to the pandemic between generations that could help in mental health resources in any future emergency situations.