An integral part of NASA's vision for the coming years is a sustained infrastructure in cislunar space. The current baseline trajectory for this facility is a Near Rectilinear Halo Orbit (NRHO), a periodic orbit in the Circular Restricted Three-Body Problem. One of the goals of the facility is to serve as a proving ground for human spaceflight operations in deep space. Thus, this investigation focuses on transfers between the baseline NRHO and a family of periodic orbits that originate from a period-doubling bifurcation along the halo family. This new family of orbits has been termed the ``butterfly" family. This investigation also provides an overview of the evolution for a large subset of the butterfly family. Transfers to multiple subsets of the family are found by leveraging different design strategies and techniques from dynamical systems theory. The different design strategies are discussed in detail, and the transfers to each of these regions are compared in terms of propellant costs and times of flight.

Orientador: Plinio Almeida Barbosa / Tese (doutorado) - Universidade Estadual de Campinas, Instituto de Estudos da Linguagem / Made available in DSpace on 2018-08-08T03:40:08Z (GMT). No. of bitstreams: 1 Meireles_AlexsandroRodrigues_D.pdf: 6729195 bytes, checksum: c6f916e8e8d1f7fcb13d314092e429dc (MD5) Previous issue date: 2007 / Resumo: Esta tese trata de reestruturações rítmicas da fala no português brasileiro ao se variar a taxa de elocução (speech rate). A reestruturação rítmica é considerada como uma reorganização entre grupos acentuais ao longo do enunciado ao se variar a taxa de elocução. A variação da taxa de elocução, por sua vez, é uma das maiores causas de modificação fonética, pois, perturbando a cadeia da fala dessa forma, pode-se avaliar as possibilidades de variação que revelariam novos padrões estáveis. A fim de explicarmos como a mudança da taxa de elocução pode modificar a estrutura rítmica da fala, dividimos a tese em três partes distintas. Na primeira parte apresentamos os fundamentos teóricos que serviram de guia para os experimentos realizados. Nessa parte introduzimos a principal motivação teórica de nossa tese, a aplicação da Teoria dos Sistemas Dinâmicos à linguagem. Os pressupostos teóricos desse programa estão presentes na Fonologia Articulatória (Browman & Goldstein, 1992) e no Modelo Dinâmico do Ritmo de Barbosa (2006), utilizados como suporte teórico dos nossos experimentos. Na segunda parte, após apresentarmos as noções básicas sobre o ritmo, relatamos um experimento acústico e um articulatório que revelam variações rítmicas nas frases estudadas com o aumento da taxa de elocução. Os principais resultados para o estudo acústico, em trechos que se reestruturaram ritmicamente, foram: a) o número de unidades VV (vogal-a-vogal) por grupo acentual aumenta proporcionalmente ao crescimento da taxa de elocução; b) a duração do grupo acentual tende a se manter constante com o aumento da taxa de elocução; c) o desvio-padrão da duração das unidades VV, bem como da duração dos grupos acentuais é menor nas taxas rápidas. Já o estudo articulatório, realizado com a utilização de um magnetômetro (EMMA), revela que a taxa de elocução tende a afetar todos os gestos dos enunciados de maneira uniforme, independentemente dos mesmos pertencerem a uma unidade VV em posição de acento frasal ou não. Na terceira parte, trabalhamos com variações rítmicas no item lexical. Especificamente estudamos a variação/mudança de proparoxítonas a paroxítonas com o aumento da taxa de elocução. Primeiramente, apresentamos aspectos históricos desta variação/mudança lexical, para, depois, apresentarmos uma análise à luz da Fonologia Articulatória. Para tanto, realizamos dois estudos: um acústico e um articulatório (EMMA). A principal conclusão para o estudo acústico foi de que a variação de proparoxítonas para formas paroxitonizadas é influenciada pela taxa de elocução, sendo que a probabilidade de encontrar formas consideradas como paroxítonas é maior nas taxas rápidas. No entanto, há fatores individuais/dialetais envolvidos, pois há falantes que nunca as produziram na taxa rápida. Já os estudos articulatórios serviram para corroborar os resultados acústicos, pois, o aumento de coarticulação entre as consoantes pós-tônicas com o crescimento da taxa de elocução explicaria a percepção de proparoxítonas como paroxítonas, sobretudo nas taxas mais rápidas. Concluindo, esta tese mostra que a explicação dinamicista de fenômenos lingüísticos de variação e mudança lingüística pode vir a conciliar aspectos fonéticos e fonológicos da linguagem. Especificamente, apresentamos aqui, como variações contínuas da fala, através do aumento da taxa de elocução, são capazes de modificar a estrutura rítmica da fala e atuar na variação/ mudança lingüística / Abstract: The present thesis deals with speech rhythmical restructurings due to speech rate variation in Brazilian Portuguese. Rhythmical restructuring is considered as a reorganization of stress groups along the utterance due to speech rate variation. Speech rate variation, on the other side, is one of the greatest causes of phonetic change, since this speech chain¿s perturbation makes possible to evaluate the possibilities of variation which would reveal new stable patterns. In order to explain how speech rate change modifies the rhythmic structure of speech, the thesis was split into three different parts. The first part presents the theoretical background on which our experiments were based upon. In this part, it is introduced the thesis¿ main theoretical motivation, the application of Dynamical Systems Theory to language. Its theoretical basis is found in the Articulatory Phonology (Browman & Goldstein, 1992) and the Dynamical Model of Rhythm (Barbosa, 2006). Both models are used as our experiments¿ theoretical basis. The second part, after presenting some basic notions about rhythm, presents an acoustical and an articulatory experiment which reveal rhythmic variations on sentences in which speech rate was varied. The acoustical study¿s main results in stretches with rhythmical restructurings are: a) the number of VV units (vowel-to-vowel) increases proportionally to speech rate increase; b) the stress group¿s duration tends to be constant with speech rate increase; c) the standard deviation of VV units¿ duration, as well as the stress groups¿ duration, is smaller at fast rates. On the other hand, the articulatory study, through the use of a magnetometer (EMMA), reveals that speech rate tends to affect all gestures in a utterance, independently of the VV unit phrasal position. The third part works with lexical rhythmic variation. Specifically, variation/ change from antepenultimate stress words to penultimate stress words is studied. Firstly, historical aspects of this lexical variation/change is presented, then, an analysis by the light of Articulatory Phonology is presented. In order to do so, two studies were made: an acoustical and an articulatory one (EMMA). The acoustical study¿s main conclusion is that antepenultimate stress words variation to penultimate stress words is influenced by speech rate. Higher probability of penultimate stress words forms is to be expected at fast rates. Nevertheless, there are individual/dialectal factors involved, since there are speakers who never produced such forms at fast rates. On the other hand, the articulatory studies were used to corroborate the previous acoustical results, for coarticulation increase between post-stress consonants with speech rate increase would explain the perception of antepenultimate stress words as penultimate stress words, especially at fast rates. Finally, this thesis shows how dynamical explanations of linguistic phenomena like linguistic change and variation may come to reconcile phonetic and phonological aspects of language. Specifically, it presents how speech continuous variations through speech rate increase are able to modify speech¿s rhythmic structure and take part in linguist change/variation / Doutorado / Doutor em Linguística

<p>The last decade has seen a significant increase in activity within cislunar space. The quantity of missions to the Lunar vicinity will only continue to rise following the collab- orative effort between NASA, ESA, JAXA and the CSA to construct the Gateway space station. One significant engineering challenge is the design of trajectories that deliver space- craft to orbits in the Lunar vicinity. In response, this study employs multi-body dynamics to investigate the geometry of two-maneuver transfers to Earth-Moon libration point or- bits. Zero-Momentum Points are employed to investigate transfer behavior in the circular- restricted 3-body problem. It is found that these points along stable invariant manifolds indicate changes in transfer geometry and represent locations where transfers exhibit limit- ing behaviors. The analysis in the lower-fidelity model is utilized to formulate initial guesses that are transitioned to higher-fidelity, ephemeris models. Retaining the solution geometry of these guesses is prioritized, and adaptations to the transition strategy are presented to circumvent numerical issues. The presented methodologies enable the procurement of desir- able trajectories in higher-fidelity models that reflect the characteristics of the initial guess generated in the circular restricted 3-body problem.</p>

Life presents fascinating examples of self-organization and emergent phenomena. In multi-cellular organisms, a multitude of cells interact to form and maintain highly complex body plans. This requires reliable communication between cells on various length scales. First, there has to be the right number of cells to preserve the integrity of the body and its size. Second, there have to be the right types of cells at the right positions to result in a functional body layout. In this thesis, we investigate theoretical feedback mechanisms for both self-organized body plan patterning and size control. The thesis is inspired by the astonishing scaling and regeneration abilities of flatworms. These worms can perfectly regrow their entire body plan even from tiny amputation fragments like the tip of the tail. Moreover, they can grow and actively de-grow by more than a factor of 40 in length depending on feeding conditions, scaling up and down all body parts while maintaining their functionality. These capabilities prompt for remarkable physical mechanisms of pattern formation. First, we explore pattern scaling in mechanisms previously proposed to describe biological pattern formation. We systematically extract requirements for scaling and highlight the limitations of these previous models in their ability to account for growth and regeneration in flatworms. In particular, we discuss a prominent model for the spontaneous formation of biological patterns introduced by Alan Turing. We characterize the hierarchy of steady states of such a Turing mechanism and demonstrate that Turing patterns do not naturally scale. Second, we present a novel class of patterning mechanisms yielding entirely self-organized and self-scaling patterns. Our framework combines a Turing system with our derived principles of pattern scaling and thus captures essential features of body plan regeneration and scaling in flatworms. We deduce general signatures of pattern scaling using dynamical systems theory. These signatures are discussed in the context of experimental data. Next, we analyze shape and motility of flatworms. By monitoring worm motility, we can identify movement phenotypes upon gene knockout, reporting on patterning defects in the locomotory system. Furthermore, we adapt shape mode analysis to study 2D body deformations of wildtype worms, which enables us to characterize two main motility modes: a smooth gliding mode due to the beating of their cilia and an inchworming behavior based on muscle contractions. Additionally, we apply this technique to investigate shape variations between different flatworm species. With this approach, we aim at relating form and function in flatworms. Finally, we investigate the metabolic control of cell turnover and growth. We establish a protocol for accurate measurements of growth dynamics in flatworms. We discern three mechanisms of metabolic energy storage; theoretical descriptions thereof can explain the observed organism growth by rules on the cellular scale. From this, we derive specific predictions to be tested in future experiments. In a close collaboration with experimental biologists, we combine minimal theoretical descriptions with state-of-the-art experiments and data analysis. This allows us to identify generic principles of scalable body plan patterning and growth control in flatworms. / Die belebte Natur bietet uns zahlreiche faszinierende Beispiele für die Phänomene von Selbstorganisation und Emergenz. In Vielzellern interagieren Millionen von Zellen miteinander und sind dadurch in der Lage komplexe Körperformen auszubilden und zu unterhalten. Dies verlangt nach einer zuverlässigen Kommunikation zwischen den Zellen auf verschiedenen Längenskalen. Einerseits ist stets eine bestimmte Zellanzahl erforderlich, sodass der Körper intakt bleibt und seine Größe erhält. Anderseits muss für einen funktionstüchtigen Körper aber auch der richtige Zelltyp an der richtigen Stelle zu finden sein. In der vorliegenden Dissertation untersuchen wir beide Aspekte, die Kontrolle von Wachstum sowie die selbstorganisierte Ausbildung des Körperbaus. Die Dissertation ist inspiriert von den erstaunlichen Skalierungs- und Regenerationsfähigkeiten von Plattwürmern. Diese Würmer können ihren Körper selbst aus winzigen abgetrennten Fragmenten -wie etwa der Schwanzspitze- komplett regenerieren. Darüberhinaus können sie auch, je nach Fütterungsbedingung, um mehr als das 40fache in der Länge wachsen oder schrumpfen und passen dabei alle Körperteile entsprechend an, wobei deren Funktionalität erhalten bleibt. Diese Fähigkeiten verlangen nach bemerkenswerten physikalischen Musterbildungsmechanismen. Zunächst untersuchen wir das Skalierungsverhalten von früheren Ansätzen zur Beschreibung biologischer Musterbildung. Wir leiten daraus Voraussetzung für das Skalieren ab und zeigen auf, dass die bekannten Modelle nur begrenzt auf Wachstum und Regeneration von Plattwürmern angewendet werden können. Insbesondere diskutieren wir ein wichtiges Modell für die spontane Entstehung von biologischen Strukturen, das von Alan Turing vorgeschlagen wurde. Wir charakterisieren die Hierarchie von stationären Zuständen solcher Turing Mechanismen und veranschaulichen, dass diese Turingmuster nicht ohne weiteres skalieren. Daraufhin präsentieren wir eine neuartige Klasse von Musterbildungsmechanismen, die vollständig selbstorgansierte und selbstskalierende Muster erzeugen. Unser Ansatz vereint ein Turing System mit den zuvor hergeleiteten Prinzipien für das Skalieren von Mustern und beschreibt dadurch wesentliche Aspekte der Regeneration und Skalierung von Plattwürmern. Mit Hilfe der Theorie dynamischer Systeme leiten wir allgemeine Merkmale von skalierenden Mustern ab, die wir im Hinblick auf experimentelle Daten diskutieren. Als nächstes analysieren wir Form und Fortbewegung der Würmer. Die Auswertung des Bewegungsverhaltens, nachdem einzelne Gene ausgeschaltet wurden, ermöglicht Rückschlüsse auf die Bedeutung dieser Gene für den Bewegungsapparat. Darüber hinaus wenden wir eine Hauptkomponentenanalyse auf die Verformungen des zweidimensionalen Wurmkörpers während der natürlichen Fortbewegung an. Damit sind wir in der Lage, zwei wichtige Fortbewegungsstrategien der Würmer zu charakterisieren: eine durch den Zilienschlag angetriebene gleichmässige Gleitbewegung und eine raupenartige Bewegung, die auf Muskelkontraktionen beruht. Zusätzlich wenden wir diese Analysetechnik auch an, um Unterschiede in der Gestalt von verschiedenen Plattwurmarten zu untersuchen. Grundsätzlich zielen alle diese Ansätze darauf ab, das Aussehen der Plattwürmer mit den damit verbundenen Funktionen verschiedener Körperteile in Beziehung zu setzen. Schlussendlich erforschen wir den Einfluss des Stoffwechsels auf den Zellaustausch und das Wachstum. Dazu etablieren wir Messungen der Wachstumsdynamik in Plattwürmern. Wir unterscheiden drei Mechanismen für das Speichern von Stoffwechselenergie, deren theoretische Beschreibung es uns ermöglicht, das beobachtete makroskopische Wachstum des Organismus mit dem Verhalten der einzelnen Zellen zu erklären. Basierend darauf leiten wir Vorhersagen ab, die nun experimentell getestet werden. In enger Zusammenarbeit mit Kollegen aus der experimentellen Biologie führen wir minimale theoretische Beschreibungen mit modernsten Experimenten und Analysetechniken zusammen. Dadurch sind wir in der Lage, Grundlagen sowohl der skalierbaren Ausbildung des Körperbaus als auch der Wachstumskontrolle bei Plattwürmern herauszuarbeiten.

<div>There is an increasing interest in future space missions devoted to the exploration of key moons in the Solar system. These many different missions may involve libration point orbits as well as trajectories that satisfy different endgames in the vicinities of the moons. To this end, an efficient design strategy to produce low-energy transfers between the vicinities of adjacent moons of a planetary system is introduced that leverages the dynamics in these multi-body systems. Such a design strategy is denoted as the moon-to-moon analytical transfer (MMAT) method. It consists of a general methodology for transfer design between the vicinities of the moons in any given system within the context of the circular restricted three-body problem, useful regardless of the orbital planes in which the moons reside. A simplified model enables analytical constraints to efficiently determine the feasibility of a transfer between two different moons moving in the vicinity of a common planet. Subsequently, the strategy builds moon-to-moon transfers based on invariant manifold and transit orbits exploiting some analytical techniques. The strategy is applicable for direct as well as indirect transfers that satisfy the analytical constraints. The transition of the transfers into higher-fidelity ephemeris models confirms the validity of the MMAT method as a fast tool to provide possible transfer options between two consecutive moons. </div><div> </div><div>The current work includes sample applications of transfers between different orbits and planetary systems. The method is efficient and identifies optimal solutions. However, for certain orbital geometries, the direct transfer cannot be constructed because the invariant manifolds do not intersect (due to their mutual inclination, distance, and/or orbital phase). To overcome this difficulty, specific strategies are proposed that introduce intermediate Keplerian arcs and additional impulsive maneuvers to bridge the gaps between trajectories that connect any two moons. The updated techniques are based on the same analytical methods as the original MMAT concept. Therefore, they preserve the optimality of the previous methodology. The basic strategy and the significant additions are demonstrated through a number of applications for transfer scenarios of different types in the Galilean, Uranian, Saturnian and Martian systems. Results are compared with the traditional Lambert arcs. The propellant and time-performance for the transfers are also illustrated and discussed. As far as the exploration of Phobos and Deimos is concerned, a specific design framework that generates transfer trajectories between the Martian moons while leveraging resonant orbits is also introduced. Mars-Deimos resonant orbits that offer repeated flybys of Deimos and arrive at Mars-Phobos libration point orbits are investigated, and a nominal mission scenario with transfer trajectories connecting the two is presented. The MMAT method is used to select the appropriate resonant orbits, and the associated impulsive transfer costs are analyzed. The trajectory concepts are also validated in a higher-fidelity ephemeris model.</div><div> </div><div>Finally, an efficient and general design strategy for transfers between planetary moons that fulfill specific requirements is also included. In particular, the strategy leverages Finite-Time Lyapunov Exponent (FTLE) maps within the context of the MMAT scheme. Incorporating these two techniques enables direct transfers between moons that offer a wide variety of trajectory patterns and endgames designed in the circular restricted three-body problem, such as temporary captures, transits, takeoffs and landings. The technique is applicable to several mission scenarios. Additionally, an efficient strategy that aids in the design of tour missions that involve impulsive transfers between three moons located in their true orbital planes is also included. The result is a computationally efficient technique that allows three-moon tours designed within the context of the circular restricted three-body problem. The method is demonstrated for a Ganymede->Europa->Io tour.</div>

Life presents fascinating examples of self-organization and emergent phenomena. In multi-cellular organisms, a multitude of cells interact to form and maintain highly complex body plans. This requires reliable communication between cells on various length scales. First, there has to be the right number of cells to preserve the integrity of the body and its size. Second, there have to be the right types of cells at the right positions to result in a functional body layout. In this thesis, we investigate theoretical feedback mechanisms for both self-organized body plan patterning and size control. The thesis is inspired by the astonishing scaling and regeneration abilities of flatworms. These worms can perfectly regrow their entire body plan even from tiny amputation fragments like the tip of the tail. Moreover, they can grow and actively de-grow by more than a factor of 40 in length depending on feeding conditions, scaling up and down all body parts while maintaining their functionality. These capabilities prompt for remarkable physical mechanisms of pattern formation. First, we explore pattern scaling in mechanisms previously proposed to describe biological pattern formation. We systematically extract requirements for scaling and highlight the limitations of these previous models in their ability to account for growth and regeneration in flatworms. In particular, we discuss a prominent model for the spontaneous formation of biological patterns introduced by Alan Turing. We characterize the hierarchy of steady states of such a Turing mechanism and demonstrate that Turing patterns do not naturally scale. Second, we present a novel class of patterning mechanisms yielding entirely self-organized and self-scaling patterns. Our framework combines a Turing system with our derived principles of pattern scaling and thus captures essential features of body plan regeneration and scaling in flatworms. We deduce general signatures of pattern scaling using dynamical systems theory. These signatures are discussed in the context of experimental data. Next, we analyze shape and motility of flatworms. By monitoring worm motility, we can identify movement phenotypes upon gene knockout, reporting on patterning defects in the locomotory system. Furthermore, we adapt shape mode analysis to study 2D body deformations of wildtype worms, which enables us to characterize two main motility modes: a smooth gliding mode due to the beating of their cilia and an inchworming behavior based on muscle contractions. Additionally, we apply this technique to investigate shape variations between different flatworm species. With this approach, we aim at relating form and function in flatworms. Finally, we investigate the metabolic control of cell turnover and growth. We establish a protocol for accurate measurements of growth dynamics in flatworms. We discern three mechanisms of metabolic energy storage; theoretical descriptions thereof can explain the observed organism growth by rules on the cellular scale. From this, we derive specific predictions to be tested in future experiments. In a close collaboration with experimental biologists, we combine minimal theoretical descriptions with state-of-the-art experiments and data analysis. This allows us to identify generic principles of scalable body plan patterning and growth control in flatworms. / Die belebte Natur bietet uns zahlreiche faszinierende Beispiele für die Phänomene von Selbstorganisation und Emergenz. In Vielzellern interagieren Millionen von Zellen miteinander und sind dadurch in der Lage komplexe Körperformen auszubilden und zu unterhalten. Dies verlangt nach einer zuverlässigen Kommunikation zwischen den Zellen auf verschiedenen Längenskalen. Einerseits ist stets eine bestimmte Zellanzahl erforderlich, sodass der Körper intakt bleibt und seine Größe erhält. Anderseits muss für einen funktionstüchtigen Körper aber auch der richtige Zelltyp an der richtigen Stelle zu finden sein. In der vorliegenden Dissertation untersuchen wir beide Aspekte, die Kontrolle von Wachstum sowie die selbstorganisierte Ausbildung des Körperbaus. Die Dissertation ist inspiriert von den erstaunlichen Skalierungs- und Regenerationsfähigkeiten von Plattwürmern. Diese Würmer können ihren Körper selbst aus winzigen abgetrennten Fragmenten -wie etwa der Schwanzspitze- komplett regenerieren. Darüberhinaus können sie auch, je nach Fütterungsbedingung, um mehr als das 40fache in der Länge wachsen oder schrumpfen und passen dabei alle Körperteile entsprechend an, wobei deren Funktionalität erhalten bleibt. Diese Fähigkeiten verlangen nach bemerkenswerten physikalischen Musterbildungsmechanismen. Zunächst untersuchen wir das Skalierungsverhalten von früheren Ansätzen zur Beschreibung biologischer Musterbildung. Wir leiten daraus Voraussetzung für das Skalieren ab und zeigen auf, dass die bekannten Modelle nur begrenzt auf Wachstum und Regeneration von Plattwürmern angewendet werden können. Insbesondere diskutieren wir ein wichtiges Modell für die spontane Entstehung von biologischen Strukturen, das von Alan Turing vorgeschlagen wurde. Wir charakterisieren die Hierarchie von stationären Zuständen solcher Turing Mechanismen und veranschaulichen, dass diese Turingmuster nicht ohne weiteres skalieren. Daraufhin präsentieren wir eine neuartige Klasse von Musterbildungsmechanismen, die vollständig selbstorgansierte und selbstskalierende Muster erzeugen. Unser Ansatz vereint ein Turing System mit den zuvor hergeleiteten Prinzipien für das Skalieren von Mustern und beschreibt dadurch wesentliche Aspekte der Regeneration und Skalierung von Plattwürmern. Mit Hilfe der Theorie dynamischer Systeme leiten wir allgemeine Merkmale von skalierenden Mustern ab, die wir im Hinblick auf experimentelle Daten diskutieren. Als nächstes analysieren wir Form und Fortbewegung der Würmer. Die Auswertung des Bewegungsverhaltens, nachdem einzelne Gene ausgeschaltet wurden, ermöglicht Rückschlüsse auf die Bedeutung dieser Gene für den Bewegungsapparat. Darüber hinaus wenden wir eine Hauptkomponentenanalyse auf die Verformungen des zweidimensionalen Wurmkörpers während der natürlichen Fortbewegung an. Damit sind wir in der Lage, zwei wichtige Fortbewegungsstrategien der Würmer zu charakterisieren: eine durch den Zilienschlag angetriebene gleichmässige Gleitbewegung und eine raupenartige Bewegung, die auf Muskelkontraktionen beruht. Zusätzlich wenden wir diese Analysetechnik auch an, um Unterschiede in der Gestalt von verschiedenen Plattwurmarten zu untersuchen. Grundsätzlich zielen alle diese Ansätze darauf ab, das Aussehen der Plattwürmer mit den damit verbundenen Funktionen verschiedener Körperteile in Beziehung zu setzen. Schlussendlich erforschen wir den Einfluss des Stoffwechsels auf den Zellaustausch und das Wachstum. Dazu etablieren wir Messungen der Wachstumsdynamik in Plattwürmern. Wir unterscheiden drei Mechanismen für das Speichern von Stoffwechselenergie, deren theoretische Beschreibung es uns ermöglicht, das beobachtete makroskopische Wachstum des Organismus mit dem Verhalten der einzelnen Zellen zu erklären. Basierend darauf leiten wir Vorhersagen ab, die nun experimentell getestet werden. In enger Zusammenarbeit mit Kollegen aus der experimentellen Biologie führen wir minimale theoretische Beschreibungen mit modernsten Experimenten und Analysetechniken zusammen. Dadurch sind wir in der Lage, Grundlagen sowohl der skalierbaren Ausbildung des Körperbaus als auch der Wachstumskontrolle bei Plattwürmern herauszuarbeiten.

<p> </p> <p>In the coming decades, numerous missions plan to exploit multi-body orbits for operations. Given the complex nature of multi-body systems, trajectory designers must possess effective tools that leverage aspects of the dynamical environment to streamline the design process and enable these missions. In this investigation, a particular class of dynamical structures, quasi-periodic orbits, are examined. This work summarizes a computational framework to construct quasi-periodic orbits and a design framework to leverage quasi-periodic motion within the path planning process. First, quasi-periodic orbit computation in the Circular Restricted Three-Body Problem (CR3BP) and the Bicircular Restricted Four-Body Problem (BCR4BP) is summarized. The CR3BP and BCR4BP serve as preliminary models to capture fundamental motion that is leveraged for end-to-end designs. Additionally, the relationship between the Earth-Moon CR3BP and the BCR4BP is explored to provide insight into the effect of solar acceleration on multi-body structures in the lunar vicinity. Characterization of families of quasi-periodic orbits in the CR3BP and BCR4BP is also summarized. Families of quasi-periodic orbits prove to be particularly insightful in the BCR4BP, where periodic orbits only exist as isolated solutions. Computation of three-dimensional quasi-periodic tori is also summarized to demonstrate the extensibility of the computational framework to higher-dimensional quasi-periodic orbits. Lastly, a design framework to incorporate quasi-periodic orbits into the trajectory design process is demonstrated through a series of applications. First, several applications were examined for transfer design in the vicinity of the Moon. The first application leverages a single quasi-periodic trajectory arc as an initial guess to transfer between two periodic orbits. Next, several quasi-periodic arcs are leveraged to construct transfer between a planar periodic orbit and a spatial periodic orbit. Lastly, transfers between two quasi-periodic orbits are demonstrated by leveraging heteroclinic connections between orbits at the same energy. These transfer applications are all constructed in the CR3BP and validated in a higher-fidelity ephemeris model to ensure the geometry persists. Applications to ballistic lunar transfers are also constructed by leveraging quasi-periodic motion in the BCR4BP. Stable manifold trajectories of four-body quasi-periodic orbits supply an initial guess to generate families of ballistic lunar transfers to a single quasi-periodic orbit. Poincare mapping techniques are used to isolate transfer solutions that possess a low time of flight or an outbound lunar flyby. Additionally, impulsive maneuvers are introduced to expand the solution space. This strategy is extended to additional orbits in a single family to demonstrate "corridors" of transfers exist to reach a type of destination motion. To ensure these transfers exist in a higher fidelity model, several solutions are transitioned to a Sun-Earth-Moon ephemeris model using a differential corrections process to show that the geometries persist.</p>

Syftet med detta arbete är att få en bild av vilka faktorer som är mest betydelsefulla för att lära sig motoriska färdigheter i bollspel och koppla detta till lärandeteori. Finns det skillnader i uppfattning om man är nybörjare eller har erfarenhet från bollspel? Spelar kön och ålder någon roll? Vilken lärandeteori värderas högst? För att ge en bakgrund till problemställningen görs en genomgång av tidigare forskning och en beskrivning av två dominerande lärandeteorier, Generella motoriska programteorin och Dynamiska systemteorin med tillhörande didaktiska och motoriska begrepp inom lärande och bollspel. Frågor har ställts i enkätform till två olika undersökningsgrupper, dels 112 studenter från enheten Idrottsvetenskap vid Lärande och samhälle, Malmö högskola och dels 129 elever från grundskolan och gymnasieskolan i två mellanskånska orter. Undersökningsgrupperna har fått värdera faktorer som anses betydelsefulla för att lära sig motoriska färdigheter i bollspel. Svaren har bearbetats i statistikprogrammet SPSS så att frekvensfördelning, skillnader och samband kan analyseras. Resultaten i undersökning 1, på studenter, visar att Sociala och psykologiska faktorer somkommunikation och motivation är högst värderade. 90 % av studenterna har värderat motivation till högst betydelse för att lära sig färdigheter i bollspel. Studenternas värdering av faktorer som sammankopplas med lärandeteorierna GMP- och DS-teorin visar att båda teorierna värderas likvärdigt. Studenterna uppvisar också samstämmighet i förhållande till kön, ålder och bollspelserfarenhet. De skillnader som finns redovisas. Elevernas svar, i undersökning 2, visar att faktorer som indikerar engagemang och motivation, har den största betydelsen för att lära sig motoriska färdigheter i bollspel. Eleverna värderar faktorer som sammankopplas till DS-teorin och ett indirekt lärande signifikant högre än faktorer som sammankopplas till GMP-teorin och ett direkt lärande. Elevundersökningen uppvisar resultat med signifikanta skillnader mellan könen. Flickor värderar faktorer som indikerar engagemang signifikant högre än pojkarna. Pojkarna värderar faktorer som indikerar fysisk förmåga signifikant högre än flickorna. Enskilda faktorer som instruktion, repetition och demonstration, har flickor värderat signifikant högre än pojkar. Betydelsen av bollspelserfarenhet och ålder har inte spelat någon större roll för hur eleverna har gjort sina värderingar. / The purpose of this work is to understand which factors are most important in learning motor skills in ball games and attach this to learning theory. Are there differences in the perception if you are a beginner or have experience from ball games? Makes gender or age any difference? Which learning theory is most valued? To give a background to the issue, a review of previous research and a description of the two dominant learning theories, General motor program theory and Dynamical systems theory is done together with didactic aspects and motor concept in learning and ball games. Questions have been raised in the questionnaire form to two different study groups, and 112 students from the institution of Sports and Science at Learning and society, Malmö University and part 129 pupils from a primary school and a secondary school in Skåne.Investigation teams have been assessing factors considered to be significant in learning motor skills in ball games. The answers have been processed in SPSS statistical programme, so that the frequency distribution, variation and correlation can be analyzed. The result of survey 1, students, reveals that the social and psychological factors such as communication and motivation are most valued. 90% of students have assessed motivation to a maximum importance to learn skills in ball games. Students ' evaluation of factors linked to learning theories GMP and DS theory shows that both theories are valued equally. Students demonstrate coherence in relation to gender, age and ball game experience. The differences are accounted for. The pupils ' responses, in study 2, shows that the factors which indicates commitment and motivation, have the greatest importance in learning motor skills in ball games. The pupils in this survey value factors linked to DS theory and an indirect learning significantly higher than factors linked to the GMP theory and direct learning. The pupils´ survey results show significant differences between the sexes. Girls value the factors indicating commitment significantly higher than boys. The boys value the factors that indicate physical ability significantly higher than the girls. Individual factors such as instruction, rehearsal and demonstration, have girls valued significantly higher than boys. The importance of ball game experience and age has not played a major role in how the pupils have done their values.

<p dir="ltr">The recent and upcoming increase in spaceflight missions to the lunar vicinity necessitates methodologies to enable operations beyond the Earth. In particular, there is a pressing need for a Space Domain Awareness (SDA) and Space Situational Awareness (SSA) architecture that encompasses the realm of space beyond the sub-geosynchronous region to sustain humanity's long-term presence in that region. Naturally, the large distances in the cislunar domain restrict access rapid and economical access from the Earth. In addition, due to the long ranges and inconsistent visibility, the volume contained within the orbit of the Moon is inadequately observed from Earth-based instruments. As such, space-based assets to supplement ground-based infrastructure are required. The need for space-based assets to support a sustained presence is further complicated by the challenging dynamics that manifest in cislunar space. Multi-body dynamical models are necessary to sufficiently model and predict the motion of any objects that operate in the space between the Earth and the Moon. The current work seeks to address these challenges in dynamical modeling and cislunar accessibility via the exploration of resonant orbits. These types of orbits, that are commensurate with the lunar sidereal period, are constructed in the Earth-Moon Circular Restricted Three-Body Problem (CR3BP) and validated in the Higher-Fidelity Ephemeris Model (HFEM). The expansive geometries and energy options supplied by the orbits are favorable for achieving recurring access between the Earth and the lunar vicinity. Sample orbits in prograde resonance are explored to accommodate circumlunar access from underlying cislunar orbit structures via Poincaré mapping techniques. Orbits in retrograde resonance, due to their operational stability, are employed in the design of space-based observer constellations that naturally maintain their relative configuration over successive revolutions. </p><p dir="ltr"> Sidereal resonant orbits that are additionally commensurate with the lunar synodic period are identified. Such orbits, along with possessing geometries inherent to sidereal resonant behavior, exhibit periodic alignments with respect to the Sun in the Earth-Moon rotating frame. This characteristic renders the orbits suitable for hosting space-based sensors that, in addition to naturally avoiding eclipses, maintain visual custody of targets in the cislunar domain. For orbits that are not eclipse-favorable, a penumbra-avoidance path constraint is implemented to compute baseline trajectories that avoid Earth and Moon eclipse events. Constellations of observers in both sidereal and sidereal-synodic resonant orbits are designed for cislunar SSA applications. Sample trajectories are assessed for the visibility of various targets in the cislunar volume, and connectivity relative to zones of interest in Earth-Moon plane. The sample constellations and observer trajectories demonstrate the utility of resonant orbits for various applications to sustain operations in cislunar space. </p>

<p dir="ltr"> With NASA's Artemis program and international collaborations focused on building a sustainable infrastructure for human exploration of the Moon, there is a growing demand for lunar exploration and complex spaceflight operations in cislunar space. However, designing efficient transfer trajectories between the Earth and the Moon remains complex and challenging. This investigation focuses on developing a dynamically informed framework for constructing low-energy transfers in the Earth-Moon-Sun Bicircular Restricted Four-body Problem (BCR4BP). Techniques within dynamical systems theory and numerical methods are exploited to construct transfers to various cislunar orbits. The analysis aims to contribute to a deeper understanding of the dynamical structures governing spacecraft motion. It addresses the characteristics of dynamical structures that facilitate the construction of propellant-efficient pathways between the Earth and the Moon, exploring periodic structures and energy properties from the Circular Restricted Three-body Problem (CR3BP) and BCR4BP. The investigation also focuses on constructing families of low-energy transfers by incorporating electric propulsion, i.e., low thrust, in an effort to reduce the time of flight and offer alternative transfer geometries. Additionally, the investigation introduces a process to transition solutions to the higher fidelity ephemeris force model to accurately model spacecraft motion through the Earth-Moon-Sun system. This research provides insights into constructing families of ballistic lunar transfers (BLTs) and cislunar low-energy flight paths (CLEFs), offering a foundation for future mission design and exploration of the Earth-Moon system.</p>