For many centuries, the study of the Sun has been an important testbed for understanding stars that are further away. One of the first astronomical observations Galileo Galilei made in 1612 with the newly invented telescope concerned the sunspots, and in 1814, Joseph von Fraunhofer employed his new spectroscope to discover the absorption lines in the solar spectrum that are now named after him. Even though more refined and new modes of observation are now available than in the days of Galileo and Fraunhofer, the study of the Sun is still high on the agenda of contemporary science, due to three guiding interests. The first is connected to the ages-old human striving to understand the structure of the larger world surrounding us. Modern telescopes, some of them even based outside the Earth’s atmosphere in space, have succeeded in observing astronomical objects that are billions of lightyears away. However, for practical reasons precision data that are important for understanding stars can still only be gained from the Sun. In a sense, the observations of far-away astronomical objects thus call for a more precise study of the closeby, of the Sun, for their interpretation. The second interest stems from the human desire to understand the essence of the world, in particular the elementary particles of which it consists. Large accelerators have been constructed to produce and collide these particles. However, man-made machines can never be as luminous as the Sun when it comes to producing particles. Solar neutrinos have thus served not only as an astronomical tool to understand the Sun’s inner workings, but their behavior on the way from the Sun to the Earth is also being studied with the aim to understand their nature and interactions. The third interest is strictly connected to life on Earth. A multitude of research has shown that even relatively slight changes in the Earth’s climate may strongly affect the living conditions in a number of densely populated areas, mainly near the ocean shore and in arid regions. Thus, great effort is expended on the study of greenhouse gases in the Earth’s atmosphere. Also the Sun, via the solar irradiance and via the effects of the so-called solar wind of magnetic particles on the Earth’s atmosphere, may affect the climate. There is no proof linking solar effects to short-term changes in the Earth’s climate. However, such effects cannot be excluded, either, making it necessary to study the Sun. The experiments summarized in the present work contribute to the present-day study of our Sun by repeating, in the laboratory, some of the nuclear processes that take place in the core of the Sun. They aim to improve the precision of the nuclear cross section data that lay the foundation of the model of the nuclear reactions generating energy and producing neutrinos in the Sun. In order to reach this goal, low-energy nuclear physics experiments are performed. Wherever possible, the data are taken in a low-background, underground environment. There is only one underground accelerator facility in the world, the Laboratory Underground for Nuclear Astrophysics (LUNA) 0.4MV accelerator in the Gran Sasso laboratory in Italy. Much of the research described here is based on experiments at LUNA. Background and feasibility studies shown here lay the base for future, higher-energy underground accelerators. Finally, it is shown that such a device can even be placed in a shallow-underground facility such as the Dresden Felsenkeller without great loss of sensitivity.

Le dieu Sol, personnification de l’astre du jour, est documenté à Rome et en Italie bien avant l’avènement de l’empire. Dieu longtemps secondaire, ce n’est que durant l’Antiquité tardive qu’il gagne en importance, mais jamais au point de supplanter Jupiter et de devenir la divinité suprême. Cette étude a pour but d’offrir une approche renouvelée de l’interprétation de son image, en mettant en valeur la constance de son iconographie, l’uniformité des messages qui lui sont associés, son importance croissante dans l’idéologie politique impériale, et ensuite de les expliquer et de les réintégrer dans une perspective plus globale du IIe au IVe siècle. Cette présente thèse a ainsi pour but d’étudier les représentations du dieu Sol, à la fois personne divine et personnification de l’astre diurne, puis d’en déduire la nature du pouvoir cosmique du dieu, notamment par l’étude des documents dans lesquels il est mis en relation directe ou indirecte avec d’autres divinités, et de mettre en relief la spécificité de l’utilisation de l’image du dieu Sol dans un contexte impérial. / The Sun deity was documented in Rome and in Italy well before the advent of the Empire. Considered secondary for a long time, this god’s importance grows only during the late Antiquity.This study aims at offering a renewed approach of its image by emphasizing the constancy of its iconography, the uniformity of the messages associated to it, and its increasing importance in the imperial political ideology which we are to explain and place in a more global perspective from the 2nd to the 4th century.Within this thesis we will study the representations of the Sun deity, as a god and as the personification of the sun. From the analysis of its documented relationship to other divinities we will establish its cosmic power and the particular use of its image in an imperial context.

The Bethe-Weizsäcker cycle consists of a set of nuclear reactions that convert hydrogen into helium and release energy in the stars. It determines the luminosity of low-metal stars at their turn-off from the main-sequence in the Hertzsprung-Russel diagram, so its rate enters the calculation of the globular clusters’ age, an independent lower limit on the age of the universe. The cycle contributes less than 1% to our Sun’s luminosity, but it produces neutrinos that can in principle be measured on Earth in underground experiments and bring direct information of the physical conditions in the solar core, provided that the nuclear reaction rate is known with sufficient precision. The 14N(p,γ)15O reaction is the slowest reaction of the Bethe-Weizs¨acker cycle and establishes its rate. Its cross section is the sum of the contributions by capture to different excited levels and to the ground state in 15O. Recent experiments studied the region of the resonance at Ep = 278 keV. Only one modern data set from an experiment performed in 1987 is available for the high-energy domain. Both energy ranges are needed to constrain the fit of the excitation function in the R-matrix framework and to obtain a reliable extrapolated S-factor at the very low astrophysical energies. The present research work studied the 14N(p,γ)15O reaction in the LUNA (Laboratory for Underground Nuclear Astrophysics) underground facility at three proton energies 0.36, 0.38, 0.40MeV, and in Dresden in the energy range Ep = 0.6 - 2MeV. In both cases, an intense proton beam was sent on solid titanium nitride sputtered targets, and the prompt photons emitted from the reaction were detected with germanium detectors. At LUNA, a composite germanium detector was used. This enabled a measurement with dramatically reduced summing corrections with respect to previous studies. The cross sections for capture to the ground state and to the excited states at 5181, 6172, and 6792 keV in 15O have been determined. An R-matrix fit was performed for capture to the ground state, that resolved the literature discrepancy of a factor two on the extrapolated S-factor. New precise branching ratios for the decay of the Ep = 278 keV resonance were measured. In Dresden, the strength of the Ep = 1058 keV resonance was measured relative to the well-known resonance at Ep = 278 keV, after checking the angular distribution. Its uncertainty is now half of the error quoted in literature. The branching ratios were also measured, showing that their recommended values should be updated. Preliminary data for the two most intense transitions off resonance are provided. The presence in the targets of the other stable nitrogen isotope 15N with its well- known isotopic abundance, allowed to measure the strength of two resonances at Ep = 430 and 897 keV of the 15N(p,αγ)12 C reaction, improving the precision for hydrogen depth profiling.

For about 20 years now, observations of 6Li in several old metal-poor stars inside the halo of our galaxy have been reported, which are largely independent of the stars’ metallicity, and which point to a possible primordial origin. The observations exceed the predictions of the Standard Big-Bang Nucleosynthesis model by a factor of 500. In the relevant energy range, no directly measured S-factors were available yet for the main production reaction 2H(α,γ)6Li, while different theoretical estimations have an uncertainty of up to two orders of magnitude. The very small cross section in the picobarn range has been measured with a deuterium gas target at the LUNA acceler- ator (Laboratory for Underground Nuclear Astrophysics), located deep underground inside Laboratori Nazionali del Gran Sasso in Italy. A beam-induced, neutron-caused background in the γ-detector occurred which had to be analyzed carefully and sub- tracted in an appropriate way, to finally infer the weak signal of the reaction. For this purpose, a method to parameterize the Compton background has been developed. The results are a contribution to the discussion about the accuracy of the recent 6Li observations, and to the question if it is necessary to include new physics into the Standard Big-Bang Nucleosynthesis model.

El estudio y practica de la literatura, en la mayoría de las veces, fueron ralizados por hombres, según valores patriarcales y tradicionales, los cuales establecieron definiciones sobre el lugar de la mujer en la sociedad, determinando así, su condición de sujeto subordinado al poder y al margen de la historia oficial. De esa manera, se hace pertinente analisar la situación cultural de la mujer, con objetivo de compreender la manera que ella es observada por si misma, por el otro y como ella percibe ese otro y transfire esa percepción a sus producciones. A partir de tales consideraciones, esta disertación de maestría tiene como objetivo problematizar la literatura escrita por mujeres por medio de un cotejo entre las novelas Eva Luna (1987) y Tropical sol da liberdade (1988) de las escritoras Isabel Allende y Ana Maria Machado, las cuales dialogan con la obra As mil e uma noites (autoría desconocida), acercando el papel de su personaje principal. Por primero se destacan algunos aspectos relacionados a la narrativa, su oralidad y su conexión con los aspectos identitarios, que aluden al discurso dominante y excludente de otras formas discursivas. Luego, serán analisadas las relaciones existentes entre literatura e historia, las aspecifidades de cada discurso, destacando las voces marginalizadas que a lo largo del tiempo, transgriden y reconfiguran los registros oficiales. Con igual destaque, al momento histórico de las obras: inicio del siglo XX periodo que Venezuela estaba bajo el régimen de la dictaduta y con un creciente proceso de capitalización, mientras tanto Brasil vivía las presiones dictatoriales en nombre de la llamada seguridad nacional . A través de la práctica comparativa, en que los puntos convergentes y divergentes son investigados se puede percebir la importancia de las narradoras y protagonistas de las novelas, las cuales destacan el lugar de la mujer en el campo de la enunciación y acción, o sea, el modelo femenino tradicional pasa a la esfera de un ser acctivo, como agente de tranformaciones personales y sociales. / O estudo e a prática da Literatura, em geral, foram efetuados pelos homens, segundo valores patriarcais e tradicionais, os quais estabeleceram as definições sobre o lugar da mulher na sociedade, determinando sua condição de sujeito subordinado ao poder e à margem da história oficial. Diante disso, torna-se pertinente analisar a situação cultural da mulher, no intuito de compreender o modo que ela é observada por si mesma, pelo outro e como ela vê esse outro e transfere isso para as suas produções. A partir dessas considerações, esta dissertação de mestrado objetiva problematizar a literatura escrita pelas mulheres por meio do cotejo entre os romances Eva Luna (1987) e Tropical sol da liberdade (1988) das escritoras Isabel Allende e Ana Maria Machado, os quais dialogam com a obra As mil e uma noites (autoria desconhecida), aproximando o papel de sua personagem principal. Em primeira instância, destacam-se algumas questões relacionadas à narrativa, sua oralidade e a sua conexão com os aspectos identitários, que remetem ao discurso dominante enquanto excludente das outras formas discursivas. A seguir, analisam-se as relações existentes entre Literatura e História, as especificidades de cada discurso, apontando como as vozes marginalizadas, ao longo do tempo, transgridem e reconfiguram os registros oficiais. Enfoca-se, igualmente, o momento histórico que as obras retratam: o início do século XX período em que a Venezuela estava exposta ao regime ditatorial e a um intenso processo de capitalização e o Brasil vivenciava as opressões da ditadura em nome da segurança nacional . Através da prática comparativa, onde os pontos convergentes e divergentes são investigados, pode-se observar a relevância das narradoras e protagonistas dos romances, as quais enfatizam o lugar da mulher no plano da enunciação e da ação, promovendo o modelo de sujeito feminino tradicional à esfera de sujeito ativo e agente de transformações pessoais e sociais.

The Bethe-Weizsäcker cycle consists of a set of nuclear reactions that convert hydrogen into helium and release energy in the stars. It determines the luminosity of low-metal stars at their turn-off from the main-sequence in the Hertzsprung-Russel diagram, so its rate enters the calculation of the globular clusters’ age, an independent lower limit on the age of the universe. The cycle contributes less than 1% to our Sun’s luminosity, but it produces neutrinos that can in principle be measured on Earth in underground experiments and bring direct information of the physical conditions in the solar core, provided that the nuclear reaction rate is known with sufficient precision. The 14N(p,γ)15O reaction is the slowest reaction of the Bethe-Weizs¨acker cycle and establishes its rate. Its cross section is the sum of the contributions by capture to different excited levels and to the ground state in 15O. Recent experiments studied the region of the resonance at Ep = 278 keV. Only one modern data set from an experiment performed in 1987 is available for the high-energy domain. Both energy ranges are needed to constrain the fit of the excitation function in the R-matrix framework and to obtain a reliable extrapolated S-factor at the very low astrophysical energies. The present research work studied the 14N(p,γ)15O reaction in the LUNA (Laboratory for Underground Nuclear Astrophysics) underground facility at three proton energies 0.36, 0.38, 0.40MeV, and in Dresden in the energy range Ep = 0.6 - 2MeV. In both cases, an intense proton beam was sent on solid titanium nitride sputtered targets, and the prompt photons emitted from the reaction were detected with germanium detectors. At LUNA, a composite germanium detector was used. This enabled a measurement with dramatically reduced summing corrections with respect to previous studies. The cross sections for capture to the ground state and to the excited states at 5181, 6172, and 6792 keV in 15O have been determined. An R-matrix fit was performed for capture to the ground state, that resolved the literature discrepancy of a factor two on the extrapolated S-factor. New precise branching ratios for the decay of the Ep = 278 keV resonance were measured. In Dresden, the strength of the Ep = 1058 keV resonance was measured relative to the well-known resonance at Ep = 278 keV, after checking the angular distribution. Its uncertainty is now half of the error quoted in literature. The branching ratios were also measured, showing that their recommended values should be updated. Preliminary data for the two most intense transitions off resonance are provided. The presence in the targets of the other stable nitrogen isotope 15N with its well- known isotopic abundance, allowed to measure the strength of two resonances at Ep = 430 and 897 keV of the 15N(p,αγ)12 C reaction, improving the precision for hydrogen depth profiling.

This paper traces La Llorona’s evolution from ancient Aztec cosmology to Trace Elements of Random Tea Parties, a contemporary novel by Felicia Luna Lemus. I argue that the protagonist’s entrenchment in her own Llorona myth ultimately inhibits the development of a queer community in collaboration with the community of her birth. While Trace Elements of Random Tea Parties leaves the tension between familial duty and personal desire unresolved, the constant narrative oscillation between past tea parties with Leti’s grandmothers and present tea parties with Leti’s chosen lesbian familia opens a space for new kinship structures to emerge, remapping the contours of the Mexican-American family and a woman’s role within it. / text

No description available.

For many centuries, the study of the Sun has been an important testbed for understanding stars that are further away. One of the first astronomical observations Galileo Galilei made in 1612 with the newly invented telescope concerned the sunspots, and in 1814, Joseph von Fraunhofer employed his new spectroscope to discover the absorption lines in the solar spectrum that are now named after him. Even though more refined and new modes of observation are now available than in the days of Galileo and Fraunhofer, the study of the Sun is still high on the agenda of contemporary science, due to three guiding interests. The first is connected to the ages-old human striving to understand the structure of the larger world surrounding us. Modern telescopes, some of them even based outside the Earth’s atmosphere in space, have succeeded in observing astronomical objects that are billions of light- years away. However, for practical reasons precision data that are important for understanding stars can still only be gained from the Sun. In a sense, the observations of far-away astronomical objects thus call for a more precise study of the closeby, of the Sun, for their interpretation. The second interest stems from the human desire to understand the essence of the world, in particular the elementary particles of which it consists. Large accelerators have been constructed to produce and collide these particles. However, man-made machines can never be as luminous as the Sun when it comes to producing particles. Solar neutrinos have thus served not only as an astronomical tool to understand the Sun’s inner workings, but their behavior on the way from the Sun to the Earth is also being studied with the aim to understand their nature and interactions. The third interest is strictly connected to life on Earth. A multitude of research has shown that even relatively slight changes in the Earth’s climate may strongly affect the living conditions in a number of densely populated areas, mainly near the ocean shore and in arid regions. Thus, great effort is expended on the study of greenhouse gases in the Earth’s atmosphere. Also the Sun, via the solar irradiance and via the effects of the so-called solar wind of magnetic particles on the Earth’s atmosphere, may affect the climate. There is no proof linking solar effects to short-term changes in the Earth’s climate. However, such effects cannot be excluded, either, making it necessary to study the Sun. The experiments summarized in the present work contribute to the present-day study of our Sun by repeating, in the laboratory, some of the nuclear processes that take place in the core of the Sun. They aim to improve the precision of the nuclear cross section data that lay the foundation of the model of the nuclear reactions generating energy and producing neutrinos in the Sun. In order to reach this goal, low-energy nuclear physics experiments are performed. Wherever possible, the data are taken in a low-background, underground environment. There is only one underground accelerator facility in the world, the Laboratory Underground for Nuclear Astro- physics (LUNA) 0.4 MV accelerator in the Gran Sasso laboratory in Italy. Much of the research described here is based on experiments at LUNA. Background and feasibility studies shown here lay the base for future, higher-energy underground accelerators. Finally, it is shown that such a device can even be placed in a shallow-underground facility such as the Dresden Felsenkeller without great loss of sensitivity.

The CNO cycle consists of a set of nuclear reactions that convert hydrogen into helium and releases energy in stars. The cycle contributes less than 1% to our Sun's luminosity, but it is responsible for detectable neutrino fluxes that can bring direct information of the physical conditions in the solar core, provided that the nuclear reaction rate is known with sufficient precision. The 14N(p,γ)15O is the slowest reaction in the CNO cycle and estabilishes its rate. The experimental study has been performed both at the LUNA 400 kV accelerator deep underground in the Gran Sasso mountain in Italy and at a 3 MV Tandetron in the Helmholtz-Zentrum Dresden-Rossendorf. A proton beam was sent on solid TiN targets and the prompt photons were collected by a composite HPGe detector (at LUNA) or by up to four HPGe detectors (Dresden). The obtained results improve the fit of the excitation function in the R-matrix framework, that is used to extrapolate the S-factor at the very low astrophysical energies. In addition, the strength of two resonances at Ep = 430 and 897 keV of the 15N(p,αγ)12C reaction were measured, improving the precision for hydrogen depth profiling.