Dallas, TX: The Staggering Wealth Gap

In the summer of 2019, I had the privilege of serving as an AmeriCorps member with an organization called Equal Heart. One of Equal Heart’s main initiatives was to provide meals to children in underserved populations, to make sure that without school in session, these children would still be receiving food. Unfortunately, in many instances, without these meals, many of the children we served would likely not know when they would be eating their next fulfilling meal. There were certain pockets of Dallas that we would travel to everyday, places that were fifteen minutes maximum from my house, but places that felt like an entirely different planet. These areas included many different locations in West Dallas, and also pockets of Northeast Dallas. Seeing these impoverished neighborhoods, and then driving back to my neighborhood, I was shocked at how vast the differences were. I live in North Dallas, in a predominantly white neighborhood where there is an abundance of parks, grocery stores, shopping centers, and recreational centers. In the areas that we served, there were not as many resources, recreational areas, or healthy grocery or dining options

Deconstructing Discourse: Gender and Neoliberal Orientalism in the Egyptian Revolution

This thesis will show that in Egyptian media and political discourse, women’s rights rhetoric serves as a façade for anti-woman nationalism, and in American media and political discourse, neoliberal support for the revolution cloaks gendered orientalism. Each is riddled with contradictions. The juxtaposition of appropriating a pro-woman label while dismissing its substance, with the dismissal of a racist concept’s label yet utilization of its substance demonstrates a grave problem in both political activism and media: indifference to probing reflection and the prioritization of a means-to-an-end attitude. This indifference and these priorities only produce short-term or surface-level solutions because they employ short-term and surface-level tactics. Consequently, revolutions do not result in the desperately desired deconstruction of hegemonic political, economic and social systems, and media does not yield in-depth investigations into the systemic problems in which the issues discussed are rooted

SABRE hyperpolarisation of vitamin B3 as a function of pH

In this work we describe how the signal enhancements obtained through the SABRE process in methanol-d4 solution are significantly affected by pH. Nicotinic acid (vitamin B3, NA) is used as the agent, and changing pH is shown to modify the level of polarisation transfer by over an order of magnitude, with significant improvements being seen in terms of the signal amplitude and relaxation rate at high pH values. These observations reveal that manipulating pH to improve SABRE enhancements levels may improve the potential of this method to quantify low concentrations of analytes in mixtures.1H NMR spectroscopy results link this change to the form of the SABRE catalyst, which changes with pH, resulting in dramatic changes in the magnitude of the ligand exchange rates. The presented data also uses the fact that the chemical shifts of the nicotinic acids NMR resonances are affected by pH to establish that hyperpolarised 1H-based pH mapping with SABRE is possible. Moreover, the strong polarisation transfer field dependence shown in the amplitudes of the associated higher order longitudinal terms offers significant opportunities for the rapid detection of hyperpolarised NA in H2O itself without solvent suppression. 1H and 13C MRI images of hyperpolarised vitamin B3 in a series of test phantoms are presented that show pH dependent intensity and contrast. This study therefore establishes that when the pH sensitivity of NA is combined with the increase in signal gain provided for by SABRE hyperpolarisation, a versatile pH probe results

Effect of electrochemical cycling on microstructure of sulfur electrodes

In lithium–sulfur (Li–S) batteries, during discharge, there is a significant morphology change as solid sulfur (S) gets dissolved and undergoes successive reduction and finally precipitates as lithium sulfide (Li2S) in porous cathode [1]. This also leads to volume change of the electrolyte in the pore space attributed to precipitation/dissolution of the solid sulfur phase. Moreover, due to the changes in the pore volume coming from the hydrostatic pressure induced by the electrolyte, the cathode microstructure shrinks or swells to accommodate these changes [2]. This leads to mechanical degradation of the electrode over cycling. Thus, the electrochemical performance of lithium sulfur battery is strongly affected by the microstructure of S electrode

Electron and nuclear spin dynamics in the thermal mixing model of dynamic nuclear polarization

A novel mathematical treatment is proposed for computing the time evolution of dynamic nuclear polarization processes in the low temperature thermal mixing regime. Without assuming any a priori analytical form for the electron polarization, our approach provides a quantitative picture of the steady state that recovers the well known Borghini prediction based on thermodynamics arguments, as long as the electrons-nuclei transition rates are fast compared to the other relevant time scales. Substantially different final polarization levels are achieved instead when the latter assumption is relaxed in the presence of a nuclear leakage term, even though very weak, suggesting a possible explanation for the deviation between the measured steady state polarizations and the Borghini prediction. The proposed methodology also allows to calculate nuclear polarization and relaxation times, once specified the electrons/nuclei concentration ratio and the typical rates of the microscopic processes involving the two spin species. Numerical results are shown to account for the manifold dynamical behaviours of typical DNP samples.Comment: 11 pages, 11 figure

El COVID-19, ¿conspiración real o relato?: una mirada crítica

La mayoría de los países del mundo comprenden que la pandemia del Coronavirus -declarada por la Organización Mundial de la Salud en marzo 2020- es una crisis global, y probablemente será la entrada a un nuevo orden internacional. Esto conlleva a que emerjan nuevos actores que van a tener importancia en el tablero estratégico mundial. Antes de entrar en el análisis global de esta pandemia, primero explicare varios asuntos que atravesaba el mundo. Muchos analistas estaban enfocados en la salida definitiva de Gran Bretaña de la Unión Europea –Brexit- , la denominada “Guerra Comercial” entre Estados Unidos y China, y el conflicto entre Irán y Estados Unidos. Además, es interesante analizar que esta no es la primera pandemia detectada por la OMS en el Siglo XXI, existieron también en 2009 - Pandemia Gripe A, más conocida como H1N1, iniciada en México luego se desplazó a Estados Unidos y Canadá. Después apareció en 2014 – 2019 el Ébola en la zona de áfrica occidental. Asimismo, la pandemia de Poliomielitis que afectó a países como Siria, Irak, Afganistán, Nigeria, Pakistán y África Central. En el año 2016, en América Latina y el Caribe apareció el Zika, y finalmente con la llegada del año 2020 apareció el virus COVID-19, más conocido como Coronavirus.Instituto de Relaciones Internacionale

Transiciones del mercado laboral de los NEETS. Una encuesta para Argentina

This study addresses the NEET phenomenon in Argentina using the country’s Household Survey for the period 2003-2018. The approach identifies NEETs’ challenges pertaining to decent job opportunities and education completion. The static perspective is extended by the use of a Multinomial Logit model, in which three potential transitions are analysed: finding a formal job, getting an informal job, or re-entering the education system. As was expected, gender, age, education level, income, and family educational and employment background were identified as highly relevant explanatory variables, but with different strength and even signs, depending on each transition. JEL codes: J21, J46, J62Este estudio aborda el fenómeno Ni-Ni en Argentina, utilizando la Encuesta Permanente de Hogares para el período 2003-2018. El enfoque identifica los desafíos vinculados con las oportunidades de trabajo decente y la finalización de la educación. Mediante el uso de un modelo Logit Multinomial, se analizan tres posibles transiciones: encontrar un trabajo formal, hallar un trabajo informal o reingresar al sistema educativo. Como se esperaba, el género, la edad, el nivel educativo, los ingresos y los antecedentes educativos y laborales de la familia se identificaron como variables explicativas muy relevantes, pero con diferente intensidad e incluso signo, según cada transición. Clasificación JEL: J21, J46, J6

Toughening mechanisms for the attachment of architectured materials: The mechanics of the tendon enthesis

Use of load-bearing materials whose functionality arises from architectured microstructures, so called architectured materials, has been hindered by the challenge of connecting them. A solution in nature is found at the tendon enthesis, a tissue that connects tendon and bone, two vastly different natural architectured materials. The tendon enthesis provides stability and allows for mobility of a joint though effective transfer of muscle forces from tendon to bone, while exhibiting toughness across a wide range of loadings. Unfortunately, many painful and physically debilitating conditions occur at or near this interface when the enthesis architecture is compromised due to injury or degeneration. Surgical and natural repairs do not reconstitute the natural toughening mechanisms of the enthesis and often fail. Hence, understanding the architectural mechanisms by which healthy and pathologic tendon entheses achieve strength and toughness would inform the development of both biological and engineered attachments.Integrating biomechanical analyses, failure characterizations, numerical simulations, and novel imaging, this thesis presents architectural mechanisms of enthesis toughening in a mouse model. Imaging uncovered fibrous architecture within the enthesis, which controlled trade-offs between strength and toughness. Ex vivo enthesis failure modes exhibited nanoscale differences in damage, milliscale differences in fiber load-sharing, and macroscale differences in energy absorption that depended on structure, composition, and the nature of loading. The elastic and failure responses of the tendon enthesis also varied with the direction of loading. This variation was due to the fibrous nature of the tendon enthesis, with a clear role for bony anatomy and fiber recruitment in enthesis toughening behavior. In vivo, , the loss of toughening mechanisms at the enthesis due to pathologic loading was evaluated by either increased (i.e., overuse) loading via downhill treadmill running or decreased (i.e., underuse) loading via botulinum toxin A induced paralysis. These loading environments led to changes in the mineralization and architecture at the tendon enthesis. These micro-architectural adaptations compromised the trade-offs between strength and toughness; overuse loading prompted active reinforcement and stiffening of the underlying trabeculae, leading a maintenance of strength and a compromise in overall toughness, whereas underloading prompted active resorption of the underlying trabecular architecture, leading to a compromise in both strength and toughness. The mouse models of the tendon enthesis failure revealed a correlation between tendon enthesis architecture and injury prevention (i.e., toughening) mechanisms. To test this concept in a clinical setting, an injury classification system was developed for patellar tendinopathy and partial patellar tendon tears. This classification system identified the stages of tear progression and prognosis by tracking changes to patellar tendon architecture. Results revealed a relationship between patellar tendon thickness and likelihood of improvement with nonoperative treatment. Taken together, this dissertation revealed how fibrous architecture can be tailored to toughen attachments between vastly different materials. This understanding can have prognostic value: tracking changes to enthesis architecture can be used as a tool for identifying candidates for various treatment options, as we showed for the patellar tendon clinical example. Furthermore, the toughening mechanisms identified here provide guidance for enhancing enthesis surgical repair and designing enthesis tissue engineered scaffolds, as well as motivating biomimetic approaches for attachment of architectured engineering material systems