755 research outputs found
Queer Critical Theory: A Key to Equity for Latinx LGBTQ+ Students in High School
Students living at multiple marginalized identities often struggle most in the K-12 public school system. This is especially true for LGBTQ+ Latinx students in the state of New Mexico where the system often suppresses opportunities for these students to thrive. A key to reversing this suppression is through understanding the lived experiences of students who live at the intersection of being LGBTQ+ and Latinx. To understand these experiences fuller, the question, what is the social experience of male Latinx LGBTQ+ students in high school and how do these social aspects affect their academic achievement, is explored. Due to the lack of research relating to marginalized students, a synthesis of related research was conducted to create what may occur if this intersection was in the literature. This synthesis involved looking at Latinx students and LGBTQ+ students individually and noting the similarities and difference between the experiences. Because of the lack of literature at the intersection a hybrid theoretical framework will be utilized of Latino Critical Race Theory (LatCrit.) in conjunction with Queer Theory. The combination of these two theories will act as Queer Critical Theory or QueerCrit., which is sparse in the literature with only a handful of studies utilizing it as a framework. One way this research can be best achieved is through a case story, involving in-depth semi-structured interviews and demographic information. It is through the combination of these two sources of data that the lived experiences of students can help establish a fuller understanding can be created about this group and how their experiences relate to equity and education. This study is unique as student voice is centered and is focused with data directly from students and not from secondary data analysis, such as health studies. This understanding is critical to create equitable education for LGBTQ+ Latinx students as there is an opportunity gap that exists between them and their non-LGBTQ+ and White counterparts. LGBTQ+ Latinx students deserve an equitable education and a key to creating this is through understanding there lived experiences as told via their voice
Design considerations for the Tandem Junction Solar Cell
Structure and operation of the tandem junction cell (TJC) are described. The impact of using only back contacts is discussed. A model is presented which explains operation of the TJC in terms of transistor action. The model is applied to predict TJC performance as a function of physical parameters
Quantifying fusion born ion populations in magnetically confined plasmas using ion cyclotron emission
Ion cyclotron emission (ICE) offers unique promise as a diagnostic of the
fusion born alpha-particle population in magnetically confined plasmas.
Pioneering observations from JET and TFTR found that ICE intensity
scales approximately linearly with the measured neutron flux from fusion
reactions, and with the inferred concentration, , of fusion-born
alpha-particles confined within the plasma. We present fully nonlinear
self-consistent kinetic simulations that reproduce this scaling for the first
time. This resolves a longstanding question in the physics of fusion
alpha-particle confinement and stability in MCF plasmas. It confirms the
magnetoacoustic cyclotron instability (MCI) as the likely emission mechanism
and greatly strengthens the basis for diagnostic exploitation of ICE in future
burning plasmas
La Traza Oculta de la Plaza de Toros de la Real Maestranza de Caballería de Sevilla. Sobre la Geometría de su Planta
Perhaps one of the most showy characteristics of the Bullring of the Real Maestranza de Caballeria of Seville is the singularity of its geometric layout, the irregularity of its arena. An unusual form to which no convincing justification has been found. There are no documents that explain it in the archives of the Corporation and there is no doubt about the solvency and dexterity of the major teachers, military engineers and architects who built it over a hundred and twenty years. Now, we think we have found an explanation for this irregular geometry. A reasoning based on the history of it construction, also in the observation of the historical and new planimetry, and especially in the knowledge that has provided us with the building of the works of reform and conservation carried out In it during these last years.Quizás una de las características más llamativas de la Plaza de la Real Maestranza de Caballería de Sevilla sea la singularidad de su traza, la irregularidad de su ruedo. Una forma insólita a la que no se ha encontrado justificación convincente. No existen documentos que la expliquen en los archivos de la Corporación y tampoco puede dudarse de la solvencia y destreza de los maestros mayores, ingenieros militares y arquitectos que a lo largo de ciento veinte años la levantaron. Ahora, creemos haber encontrado una explicación a esa geometría irregular. Un razonamiento basado en la historia de su construcción, también en la observación tanto de la planimetría histórica conservada como de los nuevos levantamientos, y sobre todo en el conocimiento que nos han proporcionado del edificio las obras de reforma y conservación llevadas a cabo en ella durante estos últimos años
cloud property retrieval using synergistic AATSR and MERIS observations
A newly developed daytime cloud property retrieval algorithm FAME-C (Freie
Universität Berlin AATSR MERIS Cloud) is presented. Synergistic observations
from AATSR and MERIS, both mounted on the polar orbiting satellite ENVISAT,
are used for cloud screening. For cloudy pixels two main steps are carried out
in a sequential form. First, a micro-physical cloud property retrieval is
performed using an AATSR near-infrared and visible channel. Cloud phase, cloud
optical thickness, and effective radius are retrieved, and subsequently cloud
water path is computed. Second, two independent cloud top height products are
retrieved. For cloud top temperature AATSR brightness temperatures are used,
while for cloud top pressure the MERIS oxygen-A absorption channel is used.
Results from the micro-physical retrieval serve as input for the two cloud top
height retrievals. Introduced are the AATSR and MERIS forward models and
auxiliary data needed in FAME-C. Also, the optimal estimation method with
uncertainty estimates, which also provides for uncertainty estimated of the
retrieved property on a pixel-basis, is presented. Within the frame of the ESA
Climate Change Initiative project first global cloud property retrievals have
been conducted for the years 2007–2009. For this time period verification
efforts are presented comparing FAME-C cloud micro-physical properties to
MODIS-TERRA derived cloud micro-physical properties for four selected regions
on the globe. The results show reasonable accuracies between the cloud micro-
physical retrievals. Biases are generally smallest for marine stratocumulus
clouds; −0.28, 0.41μm and −0.18 g m−2 for cloud optical thickness, effective
radius and cloud water path, respectively. This is also true for the root mean
square error. Also, both cloud top height products are compared to cloud top
heights derived from ground-based cloud radars located at several ARM sites.
FAME-C mostly shows an underestimation of cloud top heights when compared to
radar observations, which is partly attributed to the difficulty of accurate
cloud property retrievals for optically thin clouds and multi-layer clouds.
The bias is smallest, −0.9 km, for AATSR derived cloud top heights for single-
layer clouds
Endocrine and Ovarian Changes in Response to the Ram Effect in Medroxyprogesterone Acetate-primed Corriedale Ewes During the Breeding and Nonbreeding Season
Two experiments were performed to determine the endocrine and ovarian changes in medroxyprogesterone acetate (MAP)-primed ewes after ram introduction. Experiment 1 was performed during the mid-breeding season with 71 ewes primed with an intravaginal MAP sponge for 12 days. While the control (C) ewes (n = 35) were in permanent contact with rams, the ram effect (RE) ewes (n = 36) were isolated for 34 days prior to contact with rams. At sponge withdrawal, all ewes were joined with eight sexually experienced marking Corriedale rams and estrus was recorded over the next 4 days. The ovaries were observed by laparoscopy 4–6 days after estrus. Four weeks later, pregnancy was determined by transrectal ultrasonography. In eight ewes from each group, ovaries were ultrasonographically scanned; FSH, LH, and estradiol-17β were measured every 12 hours until ovulation or 96 hours after estrus. The response to the rams was not affected by the fact that ewes had been kept or not in close contact with males before teasing. No differences were found in FSH, LH, estradiol-17β concentrations, growth of the ovulatory follicle, onset of estrus, ovulation rate, or pregnancy rate. Experiment 2 was performed with 14 ewes during the nonbreeding season. Ewes were isolated from rams for 1 month, and received a 6-day MAP priming. Ovaries were ultrasonographically scanned every 12 hours, and FSH, LH, estradiol-17β, and progesterone were measured. Ewes that ovulated and came into estrus had higher FSH and estradiol-17β levels before introduction of the rams than did ewes that had a silent ovulation. The endocrine pattern of the induced follicular phase of ewes that came into estrus was more similar to a normal follicular phase, than in ewes that had a silent ovulation. The follicle that finally ovulated tended to emerge earlier and in a more synchronized fashion in those ewes that did come into estrus. All ewes that ovulated had an LH surge and reached higher maximum FSH levels than ewes that did not ovulate, none of which had an LH surge. We conclude that (a) the effect of ram introduction in cyclic ewes treated with MAP may vary depending on the time of the breeding season at which teasing is performed; (b) patterns of FSH, and estradiol-17β concentrations, as indicators of activity of the reproductive axis, may be used to classify depth of anestrus; and (c) the endocrine pattern of the induced follicular phase, which is related to the depth of anestrus, may be reflected in the behavioral responses to MAP priming and the ram effect
Exploiting the sensitivity of two satellite cloud height retrievals to cloud vertical distribution
This work presents a study on the sensitivity of two satellite cloud height
retrievals to cloud vertical distribution. The difference in sensitivity is
exploited by relating the difference in the retrieved cloud heights to cloud
vertical extent. The two cloud height retrievals, performed within the Freie
Universität Berlin AATSR MERIS Cloud (FAME-C) algorithm, are based on
independent measurements and different retrieval techniques. First, cloud top
temperature (CTT) is retrieved from Advanced Along Track Scanning Radiometer
(AATSR) measurements in the thermal infrared. Second, cloud top pressure (CTP)
is retrieved from Medium Resolution Imaging Spectrometer (MERIS) measurements
in the oxygen-A absorption band. Both CTT and CTP are converted to cloud top
height (CTH) using atmospheric profiles from a numerical weather prediction
model. A sensitivity study using radiative transfer simulations in the near-
infrared and thermal infrared were performed to demonstrate the larger impact
of the assumed cloud vertical extinction profile on MERIS than on AATSR top-
of-atmosphere measurements. The difference in retrieved CTH (ΔCTH) from AATSR
and MERIS are related to cloud vertical extent (CVE) as observed by ground-
based lidar and radar at three ARM sites. To increase the impact of the cloud
vertical extinction profile on the MERIS-CTP retrievals, single-layer and
geometrically thin clouds are assumed in the forward model. The results of the
comparison to the ground-based observations were separated into single-layer
and multi-layer cloud cases. Analogous to previous findings, the MERIS-CTP
retrievals appear to be close to pressure levels in the middle of the cloud.
Assuming a linear relationship, the ΔCTH multiplied by 2.5 gives an estimate
on the CVE for single-layer clouds. The relationship is weaker for multi-layer
clouds. Due to large variations of cloud vertical extinction profiles
occurring in nature, a quantitative estimate of the cloud vertical extent is
accompanied with large uncertainties. Yet, estimates of the CVE can contribute
to the characterization of a cloudy scene. To demonstrate the plausibility of
the approach, an estimate of the CVE was applied to a case study. In light of
the follow-up mission Sentinel-3 with AATSR and MERIS like instruments, Sea
and Land Surface Temperature Radiometer (SLSTR) and (Ocean and Land Colour
Instrument) OLCI, respectively, for which the FAME-C algorithm can be easily
adapted, a more accurate estimate of the CVE can be expected. OLCI will have
three channels in the oxygen-A absorption band, thus providing more pieces of
information on the cloud vertical extinction profile
Luis Gutiérrez Soto en Sevilla. 1954-1965
Between 1954 and 1965 Luis Gutiérrez Soto designed and built in Seville three buildings of large scale collective houses in the Cuba Square, the great gateway to the new extension of Triana in Los Remedios. While these buildings are included in several catalogs of contemporary architecture (1) (2) and architectural city guides (3), in the different studies of his work, they are cited only in the general indices, and the impact on the sevillian architectural context has not been considered yet. This article aims to point out the importance that these projects were in the implementation and further development of this residential typology in the city of Seville, becoming essential typological models for both local architects and future residents of these homes.Entre 1954 y 1965 Luis Gutiérrez Soto proyectó y construyó en Sevilla tres inmuebles de vivienda colectiva de gran dimensión para la Plaza de Cuba, gran puerta de ingreso al ensanche de Triana en Los Remedios. Si bien estas edificaciones se encuentran recogidas en diversos catálogos de arquitectura contemporánea (1) (2) y guías de arquitectura de la ciudad (3), en los estudios completos de su obra únicamente aparecen recogidas en los índices generales, sin que haya sido considerada su incidencia sobre el contexto arquitectónico sevillano de la época. Este artículo pretende señalar la trascendencia que estos tres proyectos tuvieron en la implantación y el desarrollo posterior de esta tipología en la ciudad de Sevilla, llegando a convertirse en referentes esenciales para arquitectos locales y futuros usuarios de estas viviendas
Food Security in Crop, Livestock and Mixed Farming Systems in Mali
This study evaluates the food security status, its determinants and the coping strategies in crop, livestock and mixed crop-livestock systems in southern Mali. Interviews were conducted with 258 households that were categorized into the three farming systems based on the revenue from livestock and crop production. A linear mixed model was used to analyse the effects of household characteristics on food security using the food consumption score (FCS), household dietary diversity score (HDDS), a modified household food insecurity access scale (mHFIAS) and coping strategies as indicators. Food consumption score was significantly influenced by the farming system with highest FCS for the livestock system (88) followed by the mixed system (77) and the crop system (69). Moreover, FCS was positively influenced by the number of crops cultivated, total farm milk production, off-farm income and number of raised chickens (p \u3c 0.1). The main difference in food intake between systems was for milk with average daily consumption of 201 ml, 110 ml and 60 ml in the livestock, mixed and crop systems, respectively. HDDS was also significantly influenced by the farming system with highest HDDS values for the livestock system (8.9), followed by the mixed system (8.2) and the crop system (8.0). Further, HDDS was positively influenced by crop diversity and number of chickens, and negatively influenced by the number of family dependents. During the food shortage period of August, households from the crop system were more food insecure than households from the mixed and livestock systems with mHFIAS values of 0.9, 1.5 and 4.3, respectively. Livestock and mixed systems were more resilient to food insecurity situations than the crop system. This study confirms the direct effect of milk production on milk consumption and the importance of livestock for enhancing food security and livelihood resilience
Time-lapse and probabilistic inversion strategies for plane-wave electromagnetic data.
L'utilisation efficace des systèmes géothermaux, la séquestration du CO2 pour limiter le changement climatique et la prévention de l'intrusion d'eau salée dans les aquifères costaux ne sont que quelques exemples qui démontrent notre besoin en technologies nouvelles pour suivre l'évolution des processus souterrains à partir de la surface. Un défi majeur est d'assurer la caractérisation et l'optimisation des performances de ces technologies à différentes échelles spatiales et temporelles. Les méthodes électromagnétiques (EM) d'ondes planes sont sensibles à la conductivité électrique du sous-sol et, par conséquent, à la conductivité électrique des fluides saturant la roche, à la présence de fractures connectées, à la température et aux matériaux géologiques. Ces méthodes sont régies par des équations valides sur de larges gammes de fréquences, permettant détudier de manières analogues des processus allant de quelques mètres sous la surface jusqu'à plusieurs kilomètres de profondeur. Néanmoins, ces méthodes sont soumises à une perte de résolution avec la profondeur à cause des propriétés diffusives du champ électromagnétique. Pour cette raison, l'estimation des modèles du sous-sol par ces méthodes doit prendre en compte des informations a priori afin de contraindre les modèles autant que possible et de permettre la quantification des incertitudes de ces modèles de façon appropriée.
Dans la présente thèse, je développe des approches permettant la caractérisation statique et dynamique du sous-sol à l'aide d'ondes EM planes. Dans une première partie, je présente une approche déterministe permettant de réaliser des inversions répétées dans le temps (time-lapse) de données d'ondes EM planes en deux dimensions. Cette stratégie est basée sur l'incorporation dans l'algorithme d'informations a priori en fonction des changements du modèle de conductivité électrique attendus. Ceci est réalisé en intégrant une régularisation stochastique et des contraintes flexibles par rapport à la gamme des changements attendus en utilisant les multiplicateurs de Lagrange. J'utilise des normes différentes de la norme l2 pour contraindre la structure du modèle et obtenir des transitions abruptes entre les régions du model qui subissent des changements dans le temps et celles qui n'en subissent pas. Aussi, j'incorpore une stratégie afin d'éliminer les erreurs systématiques de données time-lapse. Ce travail a mis en évidence l'amélioration de la caractérisation des changements temporels par rapport aux approches classiques qui réalisent des inversions indépendantes à chaque pas de temps et comparent les modèles.
Dans la seconde partie de cette thèse, j'adopte un formalisme bayésien et je teste la possibilité de quantifier les incertitudes sur les paramètres du modèle dans l'inversion d'ondes EM planes. Pour ce faire, je présente une stratégie d'inversion probabiliste basée sur des pixels à deux dimensions pour des inversions de données d'ondes EM planes et de tomographies de résistivité électrique (ERT) séparées et jointes. Je compare les incertitudes des paramètres du modèle en considérant différents types d'information a priori sur la structure du modèle et différentes fonctions de vraisemblance pour décrire les erreurs sur les données. Les résultats indiquent que la régularisation du modèle est nécessaire lorsqu'on a à faire à un large nombre de paramètres car cela permet d'accélérer la convergence des chaînes et d'obtenir des modèles plus réalistes. Cependent, ces contraintes mènent à des incertitudes d'estimations plus faibles, ce qui implique des distributions a posteriori qui ne contiennent pas le vrai modèledans les régions ou` la méthode présente une sensibilité limitée. Cette situation peut être améliorée en combinant des méthodes d'ondes EM planes avec d'autres méthodes complémentaires telles que l'ERT. De plus, je montre que le poids de régularisation des paramètres et l'écart-type des erreurs sur les données peuvent être retrouvés par une inversion probabiliste.
Finalement, j'évalue la possibilité de caractériser une distribution tridimensionnelle d'un panache de traceur salin injecté dans le sous-sol en réalisant une inversion probabiliste time-lapse tridimensionnelle d'ondes EM planes. Etant donné que les inversions probabilistes sont très coûteuses en temps de calcul lorsque l'espace des paramètres présente une grande dimension, je propose une stratégie de réduction du modèle ou` les coefficients de décomposition des moments de Legendre du panache de traceur injecté ainsi que sa position sont estimés. Pour ce faire, un modèle de résistivité de base est nécessaire. Il peut être obtenu avant l'expérience time-lapse. Un test synthétique montre que la méthodologie marche bien quand le modèle de résistivité de base est caractérisé correctement. Cette méthodologie est aussi appliquée à un test de trac¸age par injection d'une solution saline et d'acides réalisé dans un système géothermal en Australie, puis comparée à une inversion time-lapse tridimensionnelle réalisée selon une approche déterministe. L'inversion probabiliste permet de mieux contraindre le panache du traceur salin gr^ace à la grande quantité d'informations a priori incluse dans l'algorithme. Néanmoins, les changements de conductivités nécessaires pour expliquer les changements observés dans les données sont plus grands que ce qu'expliquent notre connaissance actuelle des phénomenès physiques. Ce problème peut être lié à la qualité limitée du modèle de résistivité de base utilisé, indiquant ainsi que des efforts plus grands devront être fournis dans le futur pour obtenir des modèles de base de bonne qualité avant de réaliser des expériences dynamiques.
Les études décrites dans cette thèse montrent que les méthodes d'ondes EM planes sont très utiles pour caractériser et suivre les variations temporelles du sous-sol sur de larges échelles. Les présentes approches améliorent l'évaluation des modèles obtenus, autant en termes d'incorporation d'informations a priori, qu'en termes de quantification d'incertitudes a posteriori. De plus, les stratégies développées peuvent être appliquées à d'autres méthodes géophysiques, et offrent une grande flexibilité pour l'incorporation d'informations additionnelles lorsqu'elles sont disponibles.
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The efficient use of geothermal systems, the sequestration of CO2 to mitigate climate change, and the prevention of seawater intrusion in coastal aquifers are only some examples that demonstrate the need for novel technologies to monitor subsurface processes from the surface. A main challenge is to assure optimal performance of such technologies at different temporal and spatial scales. Plane-wave electromagnetic (EM) methods are sensitive to subsurface electrical conductivity and consequently to fluid conductivity, fracture connectivity, temperature, and rock mineralogy. These methods have governing equations that are the same over a large range of frequencies, thus allowing to study in an analogous manner processes on scales ranging from few meters close to the surface down to several hundreds of kilometers depth. Unfortunately, they suffer from a significant resolution loss with depth due to the diffusive nature of the electromagnetic fields. Therefore, estimations of subsurface models that use these methods should incorporate a priori information to better constrain the models, and provide appropriate measures of model uncertainty.
During my thesis, I have developed approaches to improve the static and dynamic characterization of the subsurface with plane-wave EM methods. In the first part of this thesis, I present a two-dimensional deterministic approach to perform time-lapse inversion of plane-wave EM data. The strategy is based on the incorporation of prior information into the inversion algorithm regarding the expected temporal changes in electrical conductivity. This is done by incorporating a flexible stochastic regularization and constraints regarding the expected ranges of the changes by using Lagrange multipliers. I use non-l2 norms to penalize the model update in order to obtain sharp transitions between regions that experience temporal changes and regions that do not. I also incorporate a time-lapse differencing strategy to remove systematic errors in the time-lapse inversion. This work presents improvements in the characterization of temporal changes with respect to the classical approach of performing separate inversions and computing differences between the models.
In the second part of this thesis, I adopt a Bayesian framework and use Markov chain Monte Carlo (MCMC) simulations to quantify model parameter uncertainty in plane-wave EM inversion. For this purpose, I present a two-dimensional pixel-based probabilistic inversion strategy for separate and joint inversions of plane-wave EM and electrical resistivity tomography (ERT) data. I compare the uncertainties of the model parameters when considering different types of prior information on the model structure and different likelihood functions to describe the data errors. The results indicate that model regularization is necessary when dealing with a large number of model parameters because it helps to accelerate the convergence of the chains and leads to more realistic models. These constraints also lead to smaller uncertainty estimates, which imply posterior distributions that do not include the true underlying model in regions where the method has limited sensitivity. This situation can be improved by combining planewave EM methods with complimentary geophysical methods such as ERT. In addition, I show that an appropriate regularization weight and the standard deviation of the data errors can be retrieved by the MCMC inversion.
Finally, I evaluate the possibility of characterizing the three-dimensional distribution of an injected water plume by performing three-dimensional time-lapse MCMC inversion of planewave EM data. Since MCMC inversion involves a significant computational burden in high parameter dimensions, I propose a model reduction strategy where the coefficients of a Legendre moment decomposition of the injected water plume and its location are estimated. For this purpose, a base resistivity model is needed which is obtained prior to the time-lapse experiment. A synthetic test shows that the methodology works well when the base resistivity model is correctly characterized. The methodology is also applied to an injection experiment performed in a geothermal system in Australia, and compared to a three-dimensional time-lapse inversion performed within a deterministic framework. The MCMC inversion better constrains the water plumes due to the larger amount of prior information that is included in the algorithm. The conductivity changes needed to explain the time-lapse data are much larger than what is physically possible based on present day understandings. This issue may be related to the base resistivity model used, therefore indicating that more efforts should be given to obtain high-quality base models prior to dynamic experiments.
The studies described herein give clear evidence that plane-wave EM methods are useful to characterize and monitor the subsurface at a wide range of scales. The presented approaches contribute to an improved appraisal of the obtained models, both in terms of the incorporation of prior information in the algorithms and the posterior uncertainty quantification. In addition, the developed strategies can be applied to other geophysical methods, and offer great flexibility to incorporate additional information when available
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