EVOLUTION OF AGRICULTURAL PRODUCTION IN LATIN AMERICA

International Development,

Asie-Pacifique : une région politique en devenir (Note)

Without denying the importance of economies, the author underlines the necessity of analyzing the significance of Asia-Pacific as a political entity. The member States of the economics-oriented international organizations use the economic image of the region to gain political leverage at a regional or global level. This leads to an interrogation on the reality of « Asia-Pacific as a coherent political entity. The international relations in this area of the world also show an original pattern, insofar as the leadership of the « great powers » is questioned by « middle-sized » powers. The dialogue on collective security began recently and is a long way from achieving peace and stability in the region. It nevertheless shows the willingness of the Asia-Pacific States to overcome the difficulties of the post Cold War new world orde

Data Visualization: Emily Cordonnier (Iteration 2)

This data visualization project draws from Giorgia Lupi and Stefanie Posavec’s book Dear Data: A Friendship in 52 Weeks of Postcards. After thorough research and note-taking from given and discovered resources, students were asked to respond to the novel coronavirus and the outbreak of its affiliated illness, COVID-19. As designers, students were given the responsibility to deliver information about the current culture while also acting as a participant to history — a primary” source. The object was to document history while also allowing for moments of positivity in the midst of such anxiety and uncertainty. Students gathered data about every time they heard or read the words “coronavirus” or “COVID-19.” They were told to keep a sketchbook handy at all times. Each time they heard or read one of the phrases, they noted when it happened; what they were doing; whom they were with; and other details. From this, they created data visualizations inspired by the examples in Dear Data. ”You are actually creating a primary source of history for others to rely on in the future,” said Misty Thomas-Trout, assistant professor of art and design. “Try to enjoy this.”https://ecommons.udayton.edu/stu_vad_covid19/1007/thumbnail.jp

Home Economics and the African American Experience

What was the experience of Black women in home economics programs during the early 20th century like?https://ecommons.udayton.edu/ul_stu_projects/1003/thumbnail.jp

Oh, the Places UD Go : Decades of Photos

Archives student employee Emily Cordonnier \u2721 shares moments in the history of UD and the city in a selection of photos from the University Archives

Non-Newtonian effects in silicate liquids and crystal bearing melts

High-silica volcanic systems are considered to be the most devastating. Their highly viscous properties create a high pressurised non- fluent system which consequently relaxes the stress mostly by exploding through the brittle regime. Even if an explosion is avoided and the magma fl ows, it often generates lava domes at the top of the volcano; which, patiently, accumulate magmas that will rush down the slopes once the yield stress is crossed. Thus, such volcanoes have an explosive nature and often generate catastrophic pyroclastic flows. The modelling of magma ascent inside eruptive conduits is commonly based on fl uid mechanic principles. The difficulty of the approach is however not as much driven by the physical equations of the numerical model as the variability of the parameters of the magma itself. It is well established that the rheology of magma strongly depends on the temperature, the stress, the strain, the chemical composition, the crystal and the bubble contents. In other words, magmatic modelling involves a set of movement equations which call for a comportmental/rheological law. The movement equations give roughly equivalent results through the different models; however magma rheology is poorly controlled. The deformation of highly crystallised dome lavas is key to understanding their rheology and to fixing their failure onset. It is thus essential to adequately understand magma rheology before performing complex numerical models. Here we focus on the well studied Unzen volcano, in Japan, which had a recent period of activity between 1990 and 1995. The dome building eruptions in Unzen generate repeated dome failure and pyroclastic ows. They vary in character and behaviour from effusive domes to brittle pyroclastic events. Since then, the Unzen Scientic Drilling Project, initiated in April 1999, drilled through the volcano and sampled the eruptive conduit. This provides us with rare original samples for study and characterisation. The physico-chemical properties of these valuable samples were determined with an array of devices. Of these a large uniaxial deformation press, which can operate at high load (0 up to 300KN), and temperature (25-1200°C), will be of utmost importance. This press deforms the samples under known parameters and allows us to determine the viscosity of the melt. In this study we investigate the stress and strain-rate dependence on several glasses and Mt Unzen dome lavas. Their rheology has been determined for temperatures from 900 to 1010°C and stresses from 2 to 120 Mpa (60 MPa for crystal bearing melt) in uniaxial compression . This survey aims to distinguish the Non-Newtonian effects perturbing magmatic melts, also known as indicators of the brittle field. Towards our experiments we observed three majors viscosity decrease types: Two were dependant and typical of the solid fraction (Shear thinning & Time weakening effect). The first is instantaneous and on the whole recovered during stress release. The second is time dependent and non-recoverable. The third and last effect observed is attributed to the melt fraction and its self heating under stress (Viscous Heating Effect). We extensively investigated this last eect on pure silicate liquids and crystal bearing melts. Our findings suggest that most of the Non-Newtonians effects observed in silicate melts are linked to a self heating of the sample and can subsequently be corrected with the temperature without involving other laws than a pure viscous material. Moreover we observed that this self heating reorganise the energy distribution within the sample and by localising the strain may favours the formation of shear banding and the apparition of 'hot cracks'. Crystal bearing melts exhibit two more Non-Newtonian eects. The first one, the shear thinning, is typical of that observed in previous experiments on crystal-bearing melts. On crystal free melts, this viscosity decrease is observed at much lower magnitude. We infer that the crystal phase responds elastically to the stress applied and relaxes once the load is withdrawn. The second one, the time weakening effect, appears more complex and this regime depends on the stress (and/or strain-rate) history. We distinguish four different domains: Newtonian, non-Newtonian, crack propagation and failure domains. Each of these domains expresses itself as a dierent regime of viscosity decrease. Due to stress localisation, cracking appears in crystal-bearing melts (intra-phenocryst and/or the in the melt matrix) earlier than in crystal-free melts. For low stresses, the apparent viscosity is higher for crystal-bearing melts (as predicted by Einstein-Roscoe equations). However, while the stress (or strain rate) increases, the apparent viscosity is decreasing to that of the crystal-free melt and could be even lower if viscous heating effects are involved. Consequently, we emphasise that any numerical simulation performed without taking into account the strain-rate dependencies described above would overestimate the apparent viscosity by orders of magnitude. The magma dynamics will appears slower than in reality. Exaggerating the viscosity of a volcanic dynamic system would overestimate the time range available for a potential evacuation of the red zones. Applying a more realistic rheology would improve the early warning tools and improve the safety of the population surrounding volcanic systems

Silver Lining: Emily Cordonnier

In this project, students were asked to produce 10-by-16-inch digital posters responding to the challenge and stress of the COVID-19 pandemic. After reading Professor Misty Thomas-Trout’s handwritten letter, the students used the design tools Photoshop, Illustrator and InDesign to highlight positive messages coming from the present circumstances. “You have one meta-objective with this project: Focus on the positive messages only. If negativity is weaved in or comes across your thoughts, jot this down somewhere. Be aware of that thought, but continue to block it out with positivity.”https://ecommons.udayton.edu/stu_vad_covid19/1038/thumbnail.jp