We consider the curved N-body problem, N > 2, on a surface of constant Gaussian curvature κ ≠ 0; i.e., on spheres S2κ, for κ > 0, and on hyperbolic manifolds H2κ, for κ < 0. Our goal is to define and study relative equilibria, which are orbits whose mutual distances remain constant during the motion. We find new relative equilibria in the curved N-body problem for N = 4, and see whether bifurcations occur when passing through κ = 0. After obtaining a criterion for the existence of quadrilateral configurations on the equator of the sphere, we study two restricted 4-body problems: One in which two bodies are massless , and the second in which only one body is massless. In the former we prove the evidence for square-like relative equilibria, whereas in the latter we discuss the existence of kite-shaped relative equilibria. We will further study the 5-body problem on surfaces of constant curvature. Four of the masses arranged at the vertices of a square, and the fifth mass at the north pole of S2κ, when the curvature is positive, it is shown that relative equilibria exists when the four masses at the vertices of the square are either equal or two of them are infinitesimal, such that they do not affect the motion of the remaining three masses. In the hyperbolic case H2κ, κ < 0, there exist two values for the angular velocity which produce negative elliptic relative equilibria when the masses at the vertices of the square are equal. We also show that the square pyramidal relative equilibria with non-equal masses do not exist in H2κ. Based on the work of Florin Diacu on the existence of relative equilibria for 3-body problem on the equator of S2κ, we investigate the motion of more than three bodies. Furthermore, we study the motion of the negative curved 2-and 3-centre problems on the Poincaré upper semi-plane model. Using this model, we prove that the 2-centre problem is integrable, and we study the dynamics around the equilibrium point. Further, we analyze the singularities of the 3- centre problem due to the collision; i.e., the configurations for which at least two bodies have identical coordinates. / Graduate

Les matériaux cimentaires tels que le béton, le ciment et le plâtre sont largement utilisés dans la construction, les matières premières dont ils sont faits étant abondantes sur Terre. Cette tendance ne devrait pas changer dans les prochaines décennies. Mais ces matériaux subissent l'impact du fluage. Le fluage des matériaux cimentaires est une problématique complexe. D'une part, dans les matériaux cimentaires, le fluage est souvent couplé avec d'autres phénomènes tels que le séchage, l'hydratation et la fissuration, et peut être influencé par différents paramètres comme la température, le niveau de contrainte, la teneur en eau et la formulation. D'autre part, la mesure du fluage par un test macroscopique traditionnelle du fluage requiert du temps (il est recommandé de réaliser l'essai de fluage du béton sur plusieurs mois afin de donner une caractérisation fiable du fluage à long terme) et s'avère fastidieuse, puisque les paramètres expérimentaux doivent être bien contrôlés sur de longues périodes de temps. Cette thèse étudie la micro indentation à l'échelle de la pâte de ciment ou du plâtre pour évaluer les propriétés de fluage propre à long terme des matériaux cimentaires, en comparant les fonctions de fluage obtenues par des tests de micro indentation de quelques minutes avec celles obtenues par des expériences macroscopiques de fluage réalisées pendant de longues années. Pour la pâte de ciment, la comparaison a été faite à l'échelle du béton à l'aide d'une certaine homogénéisation. L'étude a validé le fait que un test de micro indentation de quelques minutes peut fournir une mesure des propriétés à long terme de matériaux cimentaires. Une fois validée la technique d'indentation, nous avons étudié l'effet de la microstructure (c'est-à-dire la distribution des phases) et celui de l'eau sur le fluage propre à long terme des matériaux cimentaires. L'effet de la microstructure a été étudiée sur des matériaux tels que des pâtes de C3S et de C2S ainsi que sur des compacts de C-S-H synthétique, de portlandite (CH) et leurs mélanges préparés par compression de poudres. Une attention particulière a été consacrée à créer des compacts avec de grandes fractions volumiques de phase cristalline. Pour tous les échantillons examinés, nous avons identifié le bon modèle micromécanique qui permette de prédire les résultats. Le choix du modèle micromécanique concorde avec les observations microstructurales. L'effet de l'humidité relative a été étudié par le conditionnement et l'indentation de certains de ces matériaux (par exemple la pâte de C3S, de compact de C-S-H et de compact de CH) dans différentes humidités relatives allant de 11% à 94%. L'humidité relative a eu un effet significatif sur le fluage : pour tous les matériaux testés, une plus grande humidité a conduit à un fluage plus important. Le compact de portlandite fut le plus sensible à l'humidité relative, sans doute parce que le fluage se produit au niveau des interfaces entre les cristaux de portlandite. Pour la pâte de C3S, une relation simple a été identifiée entre les propriétés de fluage à long terme et la teneur en eau. Enfin, nous avons proposé des modèles micromécaniques qui permettent la prédiction des propriétés de fluage à long terme de matériaux cimentaires avec une large gamme de fraction volumique de phase cristalline et sur une gamme d'humidités relatives étendue / Cementitious materials such as concrete, cement and gypsum are widely used in construction, as the raw materials of which they are made are abundant on Earth. Such trend is unlikely to change in the coming decades. But these materials suffer from creep. The creep of cementitious materials is a complex issue. On one hand, in cementitious materials creep is often coupled with other phenomena such as drying, hydration and cracking, and can be influenced by various parameters such as temperature, level of stress, water content and mix design. On the other hand, measuring creep by traditional macroscopic creep testing is time-consuming (creep test on concrete is recommended to be carried out over several months in order to provide a reliable characterization of long-term creep) and tedious, since experimental parameters need to be well controlled over extensive periods of time. This thesis studied microindentation at the scale of cement paste or gypsum plaster for the assessment of long-term basic creep properties of cementitious materials, by comparing creep functions obtained by minutes-long microindentation testing with those obtained with macroscopic creep experiments which lasted up to years. For cement paste, the comparison was made at the scale of concrete with the aid of upscaling tools. The study validated that minutes-long microindentation testing can provide a measurement of the long-term creep properties of cementitious materials. With the validated indentation technique, we studied the effect of microstructure (i.e., the distribution and the spatial organization of phases) and of water on long-term basic creep of cementitious materials. The effect of microstructure was studied on materials such as C3S pastes and C2S pastes as well as on compacts of synthetic C-S-H, portlandite (CH) and their mixtures prepared by compaction of powders. For all samples considered, we identified the right micromechanical model that allows predicting the results. The choice of micromechanical model was consistent with microstructural observations. The effect of relative humidity was studied by conditioning and testing some of those materials (i.e., C3S paste, compact of C-S-H, and compact of CH) in various relative humidities ranging from 11% to 94%. Relative humidity had a significant effect on creep: for all materials tested, a greater humidity led to a greater creep. The compact of portlandite was the most sensitive to relative humidity, probably because creep occurs at interfaces between portlandite crystals. For C3S paste, a linear relation was identified between long-term creep properties and water content at relative humidities ranging from 11% to 75%.Finally, we proposed micromechanical models that allow predicting long-term basic creep properties of cementitious materials with a wide range of volume fraction of crystalline phase and over a wide range of relative humidities

In Hamiltonian systems with symmetry, many previous studies have centred their attention on compact symmetry groups, but relatively little is known about the effects of noncompact groups. This thesis investigates the properties of the system of N point vortices on the hyperbolic plane H2, which has noncompact symmetry SL (2, R).The Poisson Hamiltonian structure of this dynamical system is presented and the relative equilibria conditions are found. We also describe the trajectories of relative equilibria with momentum value not equal to zero. Finally, stability criteria are found for a number of cases, focusing on N = 2, 3. These results are placed in context with the study of point vortices on the sphere, which has compact symmetry.

This master's thesis is based on a Minor Field Study (MFS) and conducted in Nicaragua during seven weeks in the spring of 2011. Nicaragua has since 2006 been given international attention due to the National Assembly's decision to criminalize the previously allowed therapeutic abortion. The procedure could be used by women whose pregnancies turned out to be life threatening is now considered illegal and can result in years of imprisonment, both for women and doctors.This study focus upon the perception and opinions regarding this law among women living in Nicaragua. Distinction was made between women living in rural and urban settings. Further, women employed within organizations were chosen as a final group of interest. The aim of the study has been to explore if these women's perception have resulted in different levels of frustration and further how this variation in frustration can be explained. The study is mainly based on interviews conducted with these three groups of women. Relative deprivation was used as an analytical framework in order to explain how women's frustration could vary.It can be concluded that there were large differences in women's awareness and knowledge of the law and rural women appeared to have a rather small perceived frustration. The deprivation increased among women in urban areas, but became most intense among women active within organizations. The study has shown that religiosity, awareness and information about the law and its consequences, organization activity and to some extent level of education have the possibilities of affecting the level of frustration. The present frustration towards the law which criminalize therapeutic abortion is however not sufficient to cause collective violence or a similar reaction.

Background: Studies have shown that children and adolescents who are relatively older than their younger peers have advantages in sports, partly because they are more biologically mature, a relative age effect (RAE). However the occurrence of RAE in physical performance is still somewhat unclear and more knowledge is needed. Aim: The aim of this study was to investigate if there were any RAEs on anthropometric measures and physical performance in adolescents who are 13 years old and active in sports. Methods: 128 subjects (78 boys, 50 girls) from Malmö idrottsakademi, a school with a sports profile, were included in this study. Measurements of height and weight were taken and the physical performance was tested for grip strength, sprint and countermovement jump (CMJ). To analyse RAEs the subjects were divided into three groups (teriles) according to their month of birth. Subjects born in Tertile 1 (Jan-Apr) and Tertile 3 (Sep-Dec) were compared together as well as within and between the sexes with independent t-tests. Results: RAEs were present in height (p=0.01), weight (p=0.01), and grip strength (0.03) where higher values were found in the relatively older subjects. Additionally, if weight was accounted for, RAE was present in CMJ where the relatively younger subjects performed better (p=0.03). Further, when sexes was analysed separately the older boys were taller (p=0.01), heavier (p=0.02), and stronger (p=0.05) compared with the younger boys. The older girls were heavier (p=0.01) compared with the younger girls whereas the younger girls got a higher CMJ weight ratio (p=0.05). Conclusion: RAEs were found on anthropometric measures, but were less clear in physical performance. This indicates that although relatively older adolescents are taller and heavier, they are not always in advantage over their younger peers regarding physical performance.

No description available.

Este trabalho tem como objetivo observar as estratégias de relativização utilizadas por estudantes brasileiros adultos de espanhol como língua estrangeira e uma eventual influência da língua 1 (L1) nas preferências constatadas nessa produção. Para tanto, fizemos, primeiramente, um estudo comparado entre as estratégias de relativização presentes no português brasileiro (PB) e no espanhol (E). Nesse estudo, observamos a presença e a ausência, junto às relativas do tipo padrão simples (sem preposição) e às relativas do tipo padrão piedpiping (com preposição), das chamadas relativas cortadoras, (TARALLO, 1993), típicas do português brasileiro (PB), e das relativas com pronomes cópia, estruturas conhecidas como de despronominalización de relativos (LOPE BLANCH, 1983) ou como de (re)duplicación de relativos (BRUCART, 1999). As duas últimas estratégias de relativização, ainda que apareçam em ambas as línguas, de acordo com diversos estudos, ocorrem com diferente frequência e aceitação na língua culta dos dois idiomas, e, portanto, têm especial importância em nossa pesquisa. Para observar as consequências que a influência dessas construções relativas poderia ocasionar na produção não nativa de estudantes brasileiros aprendizes de espanhol como língua estrangeira (ELE), analisamos uma amostra de aceitabilidade, outra de produção oral e outra de produção escrita, e verificamos que a influência da L1 ocorre em algumas circunstâncias e que essa influência se deve ao fato de que as relativas cortadoras e as despronominalizadas ou (re)duplicadas fazem parte de um conjunto de características que corroboram a existência de uma inversa assimetria entre o português do Brasil e o espanhol no que se refere à presença e/ou à ausência das formas pronominais átonas ou tônicas para a expressão dos argumentos do verbo, tal como constatou González (1994). / It is aim in this paper to observe the strategies of relativization used by Brazilian adults who study Spanish as a foreign language and a possible influence of the first language in the preferences shown in their production. For this, firstly, we did a compared study between the strategies of relativization in Brazilian Portuguese (PB) and in Spanish (E). In this study, we observe the presence and the absence, in the simple standard relative (without preposition) and the piedpiping standard relative (with preposition), relative clauses known as cortadoras relative or pp-chopping, (TARALLO, 1993), typical of Brazilian Portuguese (PB) relatives, and the relative with redundance inside relative clauses or with resumptive pronouns, structures known as despronominalizadoras (LOPE BLANCH, 1983) or as (re)duplication of relative (BRUCART, 1999). According to several studies, although the two last strategies of relativization are present in both languages, they appear with different frequency and approval in the standard language, and, therefore, have a particular importance in our investigation. To observe the consequences that the influence of these relative structures could have in the non native production of Brazilian students of ELE (Spanish as foreign language), we have analyzed a sample of acceptability, a sample of oral production and a sample of written production, and verify that the influence of the first language happens under some circumstances and that it happens because of the cortadoras relative and the despronominalizadas or (re)duplicate are part of a group of characteristics that reinforce the existence of a reverse asymmetry between Brazilian Portuguese and Spanish regarding the presence and/or the absence of the atonic or tonic pronominales forms for the expression of the verb arguments, as it was found by González (1994).

The extreme motion and load of ships have been assessed using a linear frequency domain method or a linear energy spectral method and RAOs, which may be too approximate to be used for estimation of ship motion in severest seas. The new technology uses simulation in the time domain to deal with the non-linear responses to the random seas. However, the current simulation technique has been successful only up to the sea state of 7 (“high seas”), defined by the significant wave height of 9 meters. The above cannot provide the extreme wave loads and motions for seas higher than the sea state 7. The ultimate goal of this work would be to develop a new technique that can simulate responses to the seas of states 8 and 9. The objective of the present study is to simulate the vertical relative motion and wave topping of a moored ship in the time domain by varying the significant wave heights. The analysis was able to predict with a fair accuracy the relative motion characteristics of a freely floating body in the head and beam sea conditions. The resonance aspects and its significance in the overall response are also analyzed.

The influence of nitrogen supply on relationships of relative growth rate (RGR) to leaf physiology, structural and non-structural carbon partitioning, and nitrogen- and water-use efficiencies were examined in loblolly pine (Pinus taeda L.) clonal lines differing in growth potential. Nine 18-month-old loblolly pine clones were grown in a climate-controlled greenhouse for 20 weeks under two contrasting nitrogen (N) regimes (50 and 250 ppm) and a growth analysis was carried out. Higher nitrogen increased plant RGR and largely resulted in proportional shifts in biomass from roots and stems to needles. The RGR of plants receiving higher nitrogen was increased primarily through increased leaf area ratio (LAR), which was increased through higher leaf mass fraction (LMF) and not through changes in needle morphology. Although concentrations of needle glucose in plants receiving 250 ppm N were 22 percent higher than plants receiving lower N, total non-structural carbohydrate concentrations in needles of plants receiving 50 ppm N were nearly double that of clones receiving 250 pm N, primarily due to starch accumulation of the nitrogen-deficient plants. Plants receiving 250 ppm N also had 39 and 18 percent lower starch in the coarse and fine roots, respectively. Plants receiving higher nitrogen were also more water-use efficient, but had lower photosynthetic nitrogen-use efficiency. LAR, net assimilation rate (NAR), specific leaf area (SLA), and LMF were all positively correlated with RGR, but the main influence on RGR differences among clones was LAR. In addition, leaf-level rates of photosynthesis and respiration were positively correlated with RGR; however, faster-growing clones did not exhibit greater carbon economy at the leaf level. Both instantaneous water-use efficiency (A/E) and δ13C were positively correlated with RGR and photosynthetic nitrogen-use efficiency was negatively correlated with RGR. The identification of physiological and morphological traits underpinning differences in RGR among clones and how these traits are affected by nitrogen supply provides new information on trait correlations within species and parallels broader patterns observed among species.

Formation flying is a new satellite mission concept that is concerned with clusters of satellites in neighboring orbits cooperating to perform a specific task. The tasks may be Earth observation or space-based interferometry where a cluster of small satellites is able to fulfill the same requirements as that of a larger, monolithic satellite. There exist a variety of models for the study of relative motion between two satellites. These include models based upon differential orbital elements, and relative position and velocity coordinates. Extensive work has been done on such models, both in the absence and presence of the J2 perturbation arising from the aspherical nature of the Earth, which causes variations in the orbital elements that describe the orbit. The approximate relative motion can be obtained analytically by using mean elements. However, the true orbit can only be described by the instantaneous osculating elements. An analytical method to propagate the relative motion between two satellites in highly elliptic orbits is the main focus of this thesis. The method is kinematically exact and it maintains a high degree of accuracy even in the presence of J2 perturbations. Mean orbital elements are used for orbit propagation, and expansions involving the powers of eccentricity are not utilized. The true anomaly of the reference satellite is treated as the independent variable, instead of time. The relative orbit kinematics are obtained by using a projection onto a unit sphere. This procedure allows the relative position variables to be treated as angles depending on the orbital element differences. The effect of adding short-period corrections due to J2 to the mean elements is also studied. Finally, the problem of formation reconfiguration is studied. The reconfiguration of a formation may be achieved by using impulsive thrust (velocity increments) or continuous control. This thesis presents a method to obtain the optimal velocity increments through numerical optimization, utilizing the analytical technique developed for relative orbit propagation. A continuous control law is also developed using a candidate Lyapunov function, and the asymptotic stability of the closed-loop system is ascertained.