32,685 research outputs found

    The place where curses are manufactured : four poets of the Vietnam War

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    The Vietnam War was unique among American wars. To pinpoint its uniqueness, it was necessary to look for a non-American voice that would enable me to articulate its distinctiveness and explore the American character as observed by an Asian. Takeshi Kaiko proved to be most helpful. From his novel, Into a Black Sun, I was able to establish a working pair of 'bookends' from which to approach the poetry of Walter McDonald, Bruce Weigl, Basil T. Paquet and Steve Mason. Chapter One is devoted to those seemingly mismatched 'bookends,' Walt Whitman and General William C. Westmoreland, and their respective anthropocentric and technocentric visions of progress and the peculiarly American concept of the "open road" as they manifest themselves in Vietnam. In Chapter, Two, I analyze the war poems of Walter McDonald. As a pilot, writing primarily about flying, his poetry manifests General Westmoreland's technocentric vision of the 'road' as determined by and manifest through technology. Chapter Three focuses on the poems of Bruce Weigl. The poems analyzed portray the literal and metaphorical descent from the technocentric, 'numbed' distance of aerial warfare to the world of ground warfare, and the initiation of a 'fucking new guy,' who discovers the contours of the self's interior through a set of experiences that lead from from aerial insertion into the jungle to the degradation of burning human feces. Chapter Four, devoted to the thirteen poems of Basil T. Paquet, focuses on the continuation of the descent begun in Chapter Two. In his capacity as a medic, Paquet's entire body of poems details his quotidian tasks which entail tending the maimed, the mortally wounded and the dead. The final chapter deals with Steve Mason's JohnnY's Song, and his depiction of the plight of Vietnam veterans back in "The World" who are still trapped inside the interior landscape of their individual "ghettoes" of the soul created by their war-time experiences

    Structure and adsorption properties of gas-ionic liquid interfaces

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    Supported ionic liquids are a diverse class of materials that have been considered as a promising approach to design new surface properties within solids for gas adsorption and separation applications. In these materials, the surface morphology and composition of a porous solid are modified by depositing ionic liquid. The resulting materials exhibit a unique combination of structural and gas adsorption properties arising from both components, the support, and the liquid. Naturally, theoretical and experimental studies devoted to understanding the underlying principles of exhibited interfacial properties have been an intense area of research. However, a complete understanding of the interplay between interfacial gas-liquid and liquid-solid interactions as well as molecular details of these processes remains elusive. The proposed problem is challenging and in this thesis, it is approached from two different perspectives applying computational and experimental techniques. In particular, molecular dynamics simulations are used to model gas adsorption in films of ionic liquids on a molecular level. A detailed description of the modeled systems is possible if the interfacial and bulk properties of ionic liquid films are separated. In this study, we use a unique method that recognizes the interfacial and bulk structures of ionic liquids and distinguishes gas adsorption from gas solubility. By combining classical nitrogen sorption experiments with a mean-field theory, we study how liquid-solid interactions influence the adsorption of ionic liquids on the surface of the porous support. The developed approach was applied to a range of ionic liquids that feature different interaction behavior with gas and porous support. Using molecular simulations with interfacial analysis, it was discovered that gas adsorption capacity can be directly related to gas solubility data, allowing the development of a predictive model for the gas adsorption performance of ionic liquid films. Furthermore, it was found that this CO2 adsorption on the surface of ionic liquid films is determined by the specific arrangement of cations and anions on the surface. A particularly important result is that, for the first time, a quantitative relation between these structural and adsorption properties of different ionic liquid films has been established. This link between two types of properties determines design principles for supported ionic liquids. However, the proposed predictive model and design principles rely on the assumption that the ionic liquid is uniformly distributed on the surface of the porous support. To test how ionic liquids behave under confinement, nitrogen physisorption experiments were conducted for micro‐ and mesopore analysis of supported ionic liquid materials. In conjunction with mean-field density functional theory applied to the lattice gas and pore models, we revealed different scenarios for the pore-filling mechanism depending on the strength of the liquid-solid interactions. In this thesis, a combination of computational and experimental studies provides a framework for the characterization of complex interfacial gas-liquid and liquid-solid processes. It is shown that interfacial analysis is a powerful tool for studying molecular-level interactions between different phases. Finally, nitrogen sorption experiments were effectively used to obtain information on the structure of supported ionic liquids

    Probing the Intergalactic medium properties using X-ray absorption from multiple tracers

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    Based on the Lambda Cold Dark Matter concordance cosmological model (ΛCDM), the majority of baryons exist in the Intergalactic medium (IGM). It is extremely challenging to observationally trace the IGM, especially at higher temperatures and low densities. Post reionisation, the vast majority of hydrogen and helium is ionized in the IGM and therefore, the observation of metals is essential for parametrising the IGM properties. My hypothesis is that there is significant absorption in the diffuse highly ionisied IGM and that this IGM column density increases with redshift. I use X-ray absorption in multiple tracers which yields information on the total absorbing column density of the matter between the observer and the source. Clear IGM detections require tracer sources that are bright, distant, and common enough to provide a good statistical sample of IGM lines of sight (LOS). To more accurately isolate any IGM contribution to spectral absorption, I examine each tracer host type to realistically model it, in addition to using appropriate intrinsic continuum curvature models. I test the robustness of the result from a number of perspectives. I examine the impact of the key underlying assumptions that affect the column density calculations including metallicity, ionisation and location of absorption. I look for any evidence of evolution in the parameters. In Chapters 2, 3, 4 and 5, I use gamma-ray bursts (GRBs), blazars and quasars (QSOs) to estimate IGM baryon column densities, metallicity, temperature, ionisation parameters and redshift distributions. My results for each tracer are presented in each of the respective chapters and collectively in Chapter 5 which includes comparative analysis. In conclusion, through the work in this thesis I demonstrate a consistent case for strong X-ray absorption in the IGM on the LOS to three different tracer types and that it is related to redshift. The results are consistent with the ΛCDM model for density, temperature and metallicity. Given these results, I would recommend that studies of distant objects should not follow the convention of assuming all X-ray absorption in excess of our Galaxy is attributed to the host galaxy, that the host is neutral and has solar metallicity. Instead, particularly at higher redshift, absorption in the IGM should be accounted for to give more accurate results for the tracer host properties

    A productive response to legacy system petrification

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    Requirements change. The requirements of a legacy information system change, often in unanticipated ways, and at a more rapid pace than the rate at which the information system itself can be evolved to support them. The capabilities of a legacy system progressively fall further and further behind their evolving requirements, in a degrading process termed petrification. As systems petrify, they deliver diminishing business value, hamper business effectiveness, and drain organisational resources. To address legacy systems, the first challenge is to understand how to shed their resistance to tracking requirements change. The second challenge is to ensure that a newly adaptable system never again petrifies into a change resistant legacy system. This thesis addresses both challenges. The approach outlined herein is underpinned by an agile migration process - termed Productive Migration - that homes in upon the specific causes of petrification within each particular legacy system and provides guidance upon how to address them. That guidance comes in part from a personalised catalogue of petrifying patterns, which capture recurring themes underlying petrification. These steer us to the problems actually present in a given legacy system, and lead us to suitable antidote productive patterns via which we can deal with those problems one by one. To prevent newly adaptable systems from again degrading into legacy systems, we appeal to a follow-on process, termed Productive Evolution, which embraces and keeps pace with change rather than resisting and falling behind it. Productive Evolution teaches us to be vigilant against signs of system petrification and helps us to nip them in the bud. The aim is to nurture systems that remain supportive of the business, that are adaptable in step with ongoing requirements change, and that continue to retain their value as significant business assets

    The JCMT BISTRO Survey: Multi-wavelength polarimetry of bright regions in NGC 2071 in the far-infrared/submillimetre range, with POL-2 and HAWC+

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    Polarized dust emission is a key tracer in the study of interstellar medium and of star formation. The observed polarization, however, is a product of magnetic field structure, dust grain properties and grain alignment efficiency, as well as their variations in the line of sight, making it difficult to interpret polarization unambiguously. The comparison of polarimetry at multiple wavelengths is a possible way of mitigating this problem. We use data from HAWC+/SOFIA and from SCUBA-2/POL-2 (from the BISTRO survey) to analyse the NGC 2071 molecular cloud at 154, 214 and 850 μm. The polarization angle changes significantly with wavelength over part of NGC 2071, suggesting a change in magnetic field morphology on the line of sight as each wavelength best traces different dust populations. Other possible explanations are the existence of more than one polarization mechanism in the cloud or scattering from very large grains. The observed change of polarization fraction with wavelength, and the 214-to-154 μm polarization ratio in particular, are difficult to reproduce with current dust models under the assumption of uniform alignment efficiency. We also show that the standard procedure of using monochromatic intensity as a proxy for column density may produce spurious results at HAWC+ wavelengths. Using both long-wavelength (POL-2, 850 μm) and short-wavelength (HAWC+, ≲200μm) polarimetry is key in obtaining these results. This study clearly shows the importance of multi-wavelength polarimetry at submillimeter bands to understand the dust properties of molecular clouds and the relationship between magnetic field and star formation

    Identification of new regenerative therapies in reproductive medicine and their application as a future therapeutic approach for endometrial regeneration

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    El útero es uno de los principales órganos internos del sistema reproductor femenino. Está compuesto de tres capas tisulares: perimetrio, miometrio y endometrio. Esta última capa recubre la cavidad intrauterina y es responsable directa de la implantación embrionaria (para la cual necesita un grosor endometrial mínimo). Entre las patologías que afectan al endometrio pueden distinguirse, entre otras, la atrofia endometrial (insuficiente grosor endometrial) y el síndrome de Asherman (presencia de adhesiones intrauterinas y tejido fibrótico), las cuales conforman el hilo conductor de esta tesis, compuesta de 4 artículos científicos. En ambos casos, el tejido endometrial se encuentra degenerado, lo que dificulta la implantación embrionaria, ocasionando problemas de fertilidad. A día de hoy, ninguna de estas patologías cuenta con una cura totalmente efectiva. Hasta el momento, una de las opciones terapéuticas más prometedora es la inyección de células madre. Por ello, el primer objetivo de esta tesis fue evaluar como la inyección de células madre derivadas de la médula ósea (aisladas con la detección del antígeno CD133), que había resultado ser efectiva tanto en un modelo humano como en uno animal, estaba modificando el endometrio molecularmente. Para así, intentar entender cuáles son los mecanismos paracrinos a través de los cuales llevan a cabo su acción terapéutica. Este primer estudio reveló que estas células madre parecían estar promoviendo la regeneración endometrial mediante la creación de un escenario inmunomodulador (sub-expresión del gen CXCL8), que daría paso a la sobreexpresión de genes involucrados en la regeneración tisular, como SERPINE1, IL4, y JUN. Otro tratamiento que ha ido ganando acepción con los años es el plasma rico en plaquetas, eje central del manuscrito 2. Este manuscrito evidencia como este plasma, especialmente si proviene de sangre de cordón umbilical, es capaz de promover procesos celulares, como la migración y la proliferación de las células endometriales, así como eventos regenerativos en un modelo animal con daño endometrial inducido. Sea cual sea la aproximación terapéutica de elección, se ha hipotetizado que esta regeneración tisular podría surgir de la estimulación del nicho de células madre presente en el endometrio. Es por ello que el objetivo 3 supuso el estudio de los trabajos publicados, tanto de modelos murinos como humanos, relativos a esta población de células madre endometriales. Esta búsqueda permitió concluir que aún quedan lagunas de conocimiento, bien sea en la definición de marcadores celulares específicos o en de la contribución de la médula ósea a este nicho de células madre endometriales. Finalmente, dada la mencionada falta actual de una terapia definitiva para las pacientes con atrofia endometrial o síndrome de Asherman, el cuarto y último objetivo de esta tesis supuso el estudio de todas aquellas aproximaciones que se han llevado a cabo en modelos animales que simulan este tipo de patologías humanas. Este trabajo concluyó que si bien están emergiendo nuevas terapias muy prometedoras, como son aquellas derivadas de la bioingeniería (por ejemplo, uso de hidrogeles o biomoldes), todavía falta perfeccionar y estandarizar los modelos tanto animales como in vitro que permitan una mejor traslación clínica de las mismas.The uterus is one of the main internal organs of the female reproductive system. It is composed of three different tissue layers: perimetrium, myometrium, and endometrium. This last layer covers the intrauterine cavity and is directly responsible for embryo implantation (for which it needs a certain minimum endometrial thickness). Among the pathologies affecting the endometrium, we can distinguish, among others, endometrial atrophy (characterized by an insufficient endometrial thickness) and Asherman's syndrome (a rare disease characterized by the presence of intrauterine adhesions and fibrotic tissue), which form the common thread of this thesis, composed of four original manuscripts. In both cases, the endometrial tissue is degenerated, which hinders the correct embryo implantation, causing then fertility problems. To date, none of these pathologies has a totally effective cure. So far, one of the most promising therapeutic options is the injection of stem cells. Therefore, the first objective was to evaluate how the infusion of bone marrow-derived stem cells (isolated with the antigen CD133), which had proven effective in both a human and an animal model, was modifying the endometrium at the molecular level. Then, this work aimed to understand the paracrine mechanisms through which these cells were carrying out their therapeutic and regenerative action over the endometrial tissue. This first study revealed that these stem cells appeared to be promoting endometrial regeneration by creating an immunomodulatory scenario (down-regulation of the CXCL8 gene), which would give way to the over-expression of genes (SERPINE1, IL4, and JUN) involved in tissue regeneration. Another treatment gaining acceptance over the years is a blood derivate, platelet-rich plasma, which was the focus of the second manuscript. This work shows how this plasma, mainly derived from umbilical cord blood rather than adult peripheral blood, can promote cellular processes, such as cell migration and proliferation of different types of endometrial cells (from primary culture and from stem cell lines). These plasmas also revealed how they triggered the over-expression of certain proteins involved in regenerative events in a mouse model with induced endometrial damage. Whatever the therapeutic approach of choice, it has been hypothesized that regeneration could arise from stimulation of the stem cell niche present in the endometrium. That is why objective three involved studying those works, both murine and human models, concerning this population of endometrial stem cells. This search concluded that there are still gaps in knowledge, either in the definition of specific endometrial stem cell markers or in the contribution of the bone marrow to this endogenous endometrial stem cell niche. Finally, given the aforementioned current lack of definitive therapy for patients with endometrial atrophy or Asherman's syndrome, the last objective involved studying all those approaches that have been carried out in animal models that simulate this type of human pathology. This work concluded that although new therapies are emerging, such as those derived from bioengineering (e.g. use of decellularized scaffolds or hydrogels), there is still a need to perfect and standardize both animal and in vitro models to allow a better clinical translation of these therapies

    Examining the Potential for Isotope Analyses of Carbon, Nitrogen, and Sulphur in Burned Bone from Experimental and Archaeological Contexts.

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    The aim of this project was to determine whether isotope analyses of carbon, nitrogen and sulphur can be conducted on collagen extracted from burned bone. This project was conducted in two phases: a controlled heating experiment and an archaeological application. The controlled heating experiment used cow (Bos taurus) bone to test the temperature thresholds for the conservation of δ13C, δ15N, and δ34S values. These samples were also used to test the efficacy of Fourier Transform Infrared spectroscopy (FTIR) and colour analysis, for determining the burning intensities experienced by bone burned in unknown conditions. The experiment showed that δ13C values were relatively unchanged up to 400°C (<2‰ variation), while δ15N values were relatively stable up to 200°C (0.5‰ variation). Values of δ34S were also relatively stable up to 200°C (1.4‰ variation). Colour change and FTIR data were well correlated with the change in isotope ratios. Models estimating burning intensities were created from the FTIR data. For the archaeological application, samples were selected from two early Anglo-Saxon cemetery sites: Elsham and Cleatham. Samples were selected from both inhumed and cremated individuals. Among the inhumed individuals δ13C values suggested a C3 terrestrial diet and δ15N values suggested protein derived largely from terrestrial herbivores, as expected for the early Anglo-Saxon period. However, δ34S values suggested the consumption of freshwater resources and that this consumption was related to both the age and sex of the individual. The experimental data shows that there is potential for isotope analyses of cremated remains, as during the cremation process heat exposures are not uniform across the body. The samples selected for the archaeological application, however, were not successful. Bone samples heated in controlled conditions produced viable collagen for isotope analysis; however, there are several differences between experiments conducted in a muffle furnace and open-air pyre cremation that need to be investigated further. Additionally, the influence of taphonomy on collagen survival in burned bone needs to be quantified. Finally, methods of sample selection need to be improved to find bone samples from archaeologically cremated remains that are most likely to retain viable collagen. While there is significant research that must be conducted before this research can be widely applied there are a multitude of cultures that practised cremation throughout history and around the world that could be investigated through the analyses proposed in this project
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