Escape angles in bulk chi(2) soliton interactions

We develop a theory for non-planar interaction between two identical type I spatial solitons propagating at opposite, but arbitrary transverse angles in quadratic nonlinear (or so-called chi(2)) bulk media. We predict quantitatively the outwards escape angle, below which the solitons turn around and collide, and above which they continue to move away from each other. For in-plane interaction the theory allows prediction of the outcome of a collision through the inwards escape angle, i.e. whether the solitons fuse or cross. We find an analytical expression determining the inwards escape angle using Gaussian approximations for the solitons. The theory is verified numerically.Comment: V1: 4 pages, 4 figures. V2: Accepted for publication in Physical Review E. 5 pages, 4 figures. Fig. 2 changed to be for fixed soliton width and to show soliton power. New simple relations in terms of power and pahse mismatch are include

Effects of autonomy and control on student motivation and functioning in higher education

I høyere utdanning er det viktig å tilby en mulighet for utvikling, vekst, læring og velvære for studenter. En essensiell komponent av et vellykket læringsmiljø er at studenter føler seg motiverte. Ved å bruke Selvbestemmelsesteori som et teoretisk rammeverk undersøker jeg hvordan todelingen av autonomi og kontroll henger sammen med autonom motivasjon, og hvordan autonom motivasjon relateres til ulike aspekt knyttet til psykologisk funksjon hos studenter. Avhandlingen er bygget på tre ulike studier. Den første studien benytter et tverrsnittstudie til å undersøke hvordan autonomistøtte og -hindring er knyttet til innsatsvilje, engasjement, læring og vitalitet hos realfagstudenter i høyere utdanninger. Resultater fra Structural Equal Modelling-analyse indikerer at opplevelser av autonomistøtte predikerer autonom motivasjon og igjen engasjement, innsatsvilje og læring, mens autonomihindring er negativt tilknyttet de samme variablene. Den andre studien består av et gruppeeksperiment utført i et introduksjonskurs i statistikk for universitetsstudenter. Studenter skulle løse enten et generisk oppgavesett (hvor oppgavene var basert på et datasett om dart-scoringer) eller et relevant oppgavesett (hvor oppgavene var basert på ekte forskningsdata om global oppvarming). Hypotesen var at den eksperimentelle gruppen (relevant datasett) ville oppleve øvelsen som mer autonomistøttende enn kontrollgruppen (generisk datasett). Resultater viser at studenter i kontrollgruppen opplevde en økning i negative emosjoner i løpet av øvelsen, og en reduksjon i positive emosjoner. Det ble ikke målt noen endringer i den eksperimentelle gruppen. En stimodell viste signifikante relasjoner mellom hvilket oppgavesett studentene mottok og motivasjon. Den siste studien brukte gjentatte målinger til å undersøke det todelte autonomibehovet blant studenter i høyere utdanning, og hvordan de underliggende komponentene påvirker verdisyn på faginnhold, interesse og vitalitet. Resultater basert på blandede modell-analyser indikerer at tilfredsstillelse av det grunnleggende autonomibehovet predikerer vitalitet, interesse, og verdisyn, mens autonomifrustrasjon var negativt relatert til de samme utfallsvariablene. Studiene peker på at det er viktig med en autonomistøttende utdanningskontekst for studenter. Ved å anerkjenne de underliggende prosessene som påvirker studentmotivasjon kan undervisere forsterke mer autonome former for motivasjon som igjen kan øke læringsutbytte, engasjement og velvære hos studenter. Resultatene fra disse studiene gir et bidrag om hva som påvirker studentmotivasjon og fungering, og de varierte metodikkene i studiene gir et solid grunnlag for validiteten i de overordnede funnene.Central to higher education is providing a nurturing ground for development, growth, learning, and well-being for students. A principal component of a successful learning environment for students entails the experience of feeling motivated. Using Self-Determination Theory as a framework, this thesis investigates how the dichotomy of autonomy and control relates to autonomous motivation, and how autonomous motivation relates to student functioning. The investigation is conducted through three independent studies. In the first study, a cross-sectional design was employed to investigate how autonomy support and thwarting relates to effort, engagement, learning, and vitality in higher education STEM students. Using structural equation modelling, results suggests that the experience of autonomy support positively predicts autonomous motivation and in turn engagement, effort, and learning, whereas autonomy thwarting negatively relates to the same outcome variables. In the second study, a randomized experiment was conducted in an introductory statistics course for university students. Students were given either a generic exercise set (where the assignments were based on a provided data set of dart scores) or a relevant exercise set (where the assignments were based on real research data regarding global warming), where it was hypothesized that the experimental group (i.e., the relevant data set) would be perceived as more autonomy supportive than the control group (i.e., the generic data set). Using a pre- and post-test measuring emotional affect it was found that the control group experienced a decrease in positive affect and an increase in negative affect during the assignment, while the experimental group remained unchanged. Finally, a path model showed significant relationships between the exercise type and student motivation and vitality. The final study utilized multiple real-time assessments to investigate the dichotomous relationship of perceived autonomy need satisfaction and frustration among higher education students, and how these components underpin perceived value, interest, and vitality. Using linear mixed effects models, results indicate that the satisfaction of the need for autonomy positively predicted vitality, situational interest, and perceived value, whereas autonomy need frustration was negatively related to the same outcome variables. To conclude, the studies highlight the importance of providing an autonomy supportive educational context for students. By acknowledging and taking the underlying processes that affect student motivation into account, teachers and instructors can promote autonomous forms of motivation which can increase learning, persistence, engagement, and vitality in students. The results from these studies further expand upon the knowledge as to what affects student motivation and functioning, and the diversity of the methodological approaches to the different studies provides strong support for the validity of the overall hypotheses.Doktorgradsavhandlin

Characterization of seabed properties from Scholte waves acquired on floating ice on shallow water

Seismic surveying of the coastal areas in the Arctic is best facilitated during wintertime when the sea ice is land‐fast. This eases the logistics of the operation and assures that there is no damage made to the vulnerable tundra. Seismic experiments on floating ice on shallow water performed in a fjord in Svalbard in the Norwegian Arctic show prominent Scholte waves. The dispersion relation of Scholte waves can provide the shear wave velocities of the seabed sediments. Scholte wave data can potentially be obtained when the seismic source and geophone receivers are both placed on top of the floating ice. However, the Scholte wave data become more distinct by using an air gun lowered some metres below the ice. A rock physics model based on a two‐step differential effective medium scheme has been tuned to predict seismic properties found for very loose sediments, among these very high P‐wave to S‐wave velocity ratios. The rock physics model enables us to convert seismic velocities obtained from Scholte wave data to quantitative estimates of the sediment composition

The Effects of Perinatal Fluoxetine Exposure on Social and Non-Social Investigation Behaviors in a Novel Environment

Selective serotonin reuptake inhibitors (SSRIs) are increasingly prescribed as medication for various affective disorders during pregnancy. SSRIs cross the placenta and affect serotonergic neurotransmission in the fetus, but the neurobehavioral consequences for the offspring remain largely unclear. Recent research has linked perinatal SSRI exposure to alterations in both social and non-social aspects of behavior. However, this research has mainly focused on behavior within simplified environments. The current study investigates the effects of perinatal exposure to SSRIs on social and non-social investigation behaviors when the individual is introduced to a novel seminatural environment with unfamiliar conspecifics. During the perinatal period (gestational day 1 until postnatal day 21), rat dams received daily either SSRI treatment (fluoxetine 10 mg/kg) or vehicle. Four cohorts of offspring, each consisting of four males and four females, were observed in adulthood during the first hour within a seminatural environment. The results showed that perinatal fluoxetine exposure altered aspects of non-social, but not social, investigation behaviors. Both fluoxetine exposed male and female rats spent more time on walking/running than controls, while fluoxetine exposed females also walked/ran more often than control animals. Furthermore, compared to control, fluoxetine exposed female rats spent less time exploring objects and specific elements in the physical environment. We suggest that perinatal exposure to SSRI lead to a quicker, less detailed investigation strategy in novel environments, and that the alteration is most pronounced in females. Whether this effect is disadvantageous or not is yet to be revealed

Leadership challenges for Joint Force commanders during the transition from a high-intensity to a low-intensity conflict

A Joint Force Commander (JFC) leading military joint operations faces several complex challenges. The purpose of this article is to investigate some of the challenges a Joint Force Commander may face when a conflict changes character from being a high-intensity conflict to becoming a low-intensity conflict. Sources of evidence: In connection with command and control, especially issues concerning different cultures and the understanding of this can be the biggest challenge for a Joint Force Commander during the transition to a low intensity conflict as a peace support operation setting. Main argument: Being able to anticipate some of these problems will be essential to a Joint Force Commander's ability to exercise leadership and command and control. Conclusions: Furthermore, target selection and information operations have proven to be two factors that will have a greater importance in the planning and conduct of operations during a transition from a high-intensity conflict to a low-intensity conflict.publishedVersio