An Object-Oriented, Python-Based Moving Mesh Hydrodynamics Code Inspired by Astrophysical Problems

The role of radiative cooling plays an important role in the formation of structures in collapsing gas. In this dissertation I examine the impact of cooling in two formation scenarios: first, the role of H2 cooling in collapsing gas in primordial dark matter halos in the possible formation of supermassive black holes; second, low metallicity cooling in collapsing clouds and its possible role in explaining low-metallicity globular clusters. Further, I introduce a new hydrodynamics code, with a design guided by current software principles. In chapter 2, I examined the proposed mechanism to explain the formation of super-massive black holes through direct collapse. The presence of quasars at redshifts z > 6 indicates the existence of supermassive black holes (SMBHs) as massive as a few times 10^9 mass of the sun, challenging models for SMBH formation. One pathway is through the direct collapse of gas in T_vir ≳ 10^4 K halos; however, this requires the suppression of H2 cooling to prevent fragmentation. In this dissertation, I examine a proposed mechanism for this suppression which relies on cold-mode accretion flows leading to shocks at high densities (n > 10^4 cm^−3 ) and temperatures (T > 10^4 K). In such gas, H2 is efficiently collisionally dissociated. I use high-resolution numerical simulations to test this idea, demonstrating that such halos typically have lower temperature progenitors, in which cooling is efficient. Those halos do show filamentary flows; however, the gas shocks at or near the virial radius (at low densities), thus preventing the proposed collisional mechanism from operating. I do find that, if we artificially suppress H2 formation with a high UV background, so as to allow gas in the halo center to enter the high-temperature, high-density “zone of no return”, it will remain there even if the UV flux is turned off, collapsing to high density at high temperature. Due to computational limitations, we simulated only three halos. However, we demonstrate, using Monte Carlo calculations of 10^6 halo merger histories, that a few rare halos could assemble rapidly enough to avoid efficient H2 cooling in all of their progenitor halos, provided that the UV background exceeds J_21 ∼ few at redshifts as high as z ∼ 20. In chapter 3, I explore the relative role of small-scale fragmentation and global collapse in low-metallicity clouds, pointing out that in such clouds the cooling time may be longer than the dynamical time, allowing the cloud to collapse globally before it can fragment. This, I suggest, may help to explain the formation of the low-metallicity globular cluster population, since such dense stellar systems need a large amount of gas to be collected in a small region (without significant feedback during the collapse). To explore this further, I carried out numerical simulations of low-metallicity Bonner-Ebert stable gas clouds, demonstrating that there exists a critical metallicity (between 0.001 and 0.01 metallicity of the sun ) below which the cloud collapses globally without fragmentation. I also run simulations including a background radiative heating source, showing that this can also produce clouds that do not fragment, and that the critical metallicity – which can exceed the no-radiation case – increases with the heating rate. Lastly in chapter 4, I describe the structure and implementation of the new open-source parallel moving-mesh hydrodynamic code, Python Hydro-Dynamics (phd). The code has been written from the ground up to be easy to use and facilitate future modifications. The code is written in a mixture of Python and Cython and makes extensive use of object-oriented programming. I outline the algorithms used and describe the design philosophy and the reasoning of my choices during the code development. I end by validating the code through a series of test problems

Live Weather Data

On this project we aredeveloping a portable module that will use a tethered smart phone to take advantage of its data transmission, Global Positioning System (GPS) data and processing capabilities. This will enable us to develop a network of meteorological data loggers that will be capable of transmitting live data. This data would be of valuable importance for the meteorology community and would enable them to do more accurate predictions of the weather changes. This is very useful since the will be able to make more accurate forecasts and with more time in advance. On Discovery day we will be presenting the prototype of our board, and we will demonstrate how it sends data to a smartphone connected through blue-tooth wireless protocol

On the impact of early marriage on schooling outcomes in sub-Saharan Africa and South West Asia

This paper examines the effect of age of marriage on women's schooling outcomes for 36 countries from Sub-Saharan Africa and South West Asia. We employ an instrumental variable approach to account for the endogeneity of early marriage driven by socio-economic and cultural factors. Our results show that delaying early marriage by one year is associated with an increase of half a year of education in Sub-Saharan Africa and nearly one third of a year of education in South West Asia as well as a lower likelihood of dropping out from secondary school of 5.5% in South West Asia

"Let the memories begin". The family photo album and contemporary Spanish autobiography

This article explores the interactions between photography and self-writing in contemporary Spanish autobiography. Through the analysis of autobiographies by Carmen Martín Gaite and Paloma Díaz-Mas, the presence of the family album is revealed as a structural device and as an essential constituent of a dialogue between image and word that transcends the boundaries of Spanish autobiographical writing towards the constitution of experimental hybrid texts, or «imagetext», according to the concept created by W. J. T. Mitchell.Publisher PDFPeer reviewe

Donde se forman las expediciones definitivas : El hombre perdido (1947) y las novelas de la nebulosa de Ramón Gómez de la Serna

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Characterization of the killer toxin KTCf20 from wickerhamomyces anomalus, a potential biocontrol agent against wine spoilage yeasts

Wickerhamomyces anomalus Cf20 secretes the killer toxin KTCf20 that inhibits several wine spoilage yeasts of the species Pichia guilliermondii, P. membranifaciens, Brettanomyces bruxellensis and Dekkera anomala. KTCf20 binds cell wall extracts from the sensitive target P. guilliermondii Cd6; however, this capacity was lost when cell wall extracts were pre-treated with fungal β-glucanase. Pustulan and laminarin inhibited killer activity, suggesting that β-1,3 and β-1,6-glucans may be the putative binding sites for KTCf20 on the cell wall of sensitive cells. The toxin was produced and showed to be stable and highly active at physicochemical conditions suitable for winemaking process. In addition, the strain Cf20 is compatible with Saccharomyces cerevisiae in co-culture conditions being potential its application in a mixed starter culture. These data suggest that W. anomalus Cf20 and/or KTCf20 are promising biocontrol agents against spoilage yeasts during wine-making process.Fil: Fernandez de Ullivarri, Miguel. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Tucumán. Centro de Referencia para Lactobacilos; ArgentinaFil: Mendoza, Lucia Margarita. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Tucumán. Centro de Referencia para Lactobacilos; ArgentinaFil: Raya, Raul Ricardo. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Tucumán. Centro de Referencia para Lactobacilos; Argentin