668 research outputs found
Planetary circulations in the presence of transient and self-induced heating
The research program focuses on large-scale circulations and their interaction with the global convective pattern. An 11-year record of global cloud imagery and contemporaneous fields of motion and temperature have been used to investigate organized convection and coherent variability of the tropical circulation operating on intraseasonal time scales. This study provides a detailed portrait of tropical variability associated with the so-called Madden-Julian Oscillation (MJO). It reveals the nature, geographical distribution, and seasonality of discrete convective signal, which is a measure of feedback between the circulation and the convective pattern. That discrete spectral behavior has been evaluated in light of natural variability of the ITCZ associated with climatological convection. A composite signature of the MJO, based on cross-covariance statistics of cloud cover, motion, and temperature, has been constructed to characterize the lifecycle of the disturbance in terms of these properties. The composite behavior has also been used to investigate the influence the MJO exerts on the zonal-mean circulation and the involvement of the MJO in transfers of momentum between the atmosphere and the solid Earth. The aforementioned observational studies have led to the production of two animations. One reveals the convective signal in band-pass filtered OLR and compares it to climatological convection. The other is a 3-dimensional visualization of the composite lifecycle of the MJO. With a clear picture of the MJO in hand, feedback between the circulation and the convective pattern can be diagnosed meaningfully in numerical simulations. This process is being explored in calculations with the linearized primitive equations on the sphere in the presence of realistic stability and shear. The numerical framework represents climatological convection as a space-time stochastic process and wave-induced convection in terms of the vertically-integrated moisture flux convergence. In these calculations, frictional convergence near the equator emerges as a key to feedback between the circulation and the convective pattern. At low latitudes, nearly geostrophic balance in the boundary layer gives way to frictional balance. This shifts the wave-induced convection into phase with the temperature anomaly and allows the attending heating to feed back positively onto the circulation. The calculations successfully reproduce the salient features of the MJO. They are being used to understand the growth and decay phases of the composite lifecycle and the conditions that favor amplification of the MJO
Rare or poorly known scorpions from Colombia. II. Redescription of \u3cem\u3eTityus columbianus\u3c/em\u3e (Thorell, 1876) (Scorpiones: Buthidae)
A fully illustrated redescription is herein presented of Tityus columbianus (Thorell, 1876). It includes a description of the adult male, an update of its geographical distribution, and detailed information about age-related individual variation, with comments on the taxonomy of the “Tityus clathratus” group
Rare or poorly known scorpions from Colombia. I. Redescription of \u3cem\u3eTityus macrochirus\u3c/em\u3e Pocock, 1897 (Scorpiones: Buthidae)
A fully illustrated redescription is herein presented of Tityus macrochirus Pocock, 1897, based upon a series of specimens of both sexes recently collected in a new location near the type locality. We include an update of its geographical distribution and detailed information about age-related individual variation
The Relationship Between Socioeconomic Status, Course Delivery Method, and Student Success at a State College: A Single Institution Analysis
In an effort to improve instruction and better accommodate the needs of students, community colleges are offering courses delivered in a variety of delivery formats that require students to have some level of technology fluency to be successful in the course. This study was conducted to investigate the relationship between student socioeconomic status (SES), course delivery method, and course type on enrollment, final course grades, course completion status, and course passing status at a state college.
A dataset for 20,456 students of low and not low SES enrolled in science, technology, engineering, and mathematics (STEM) course types delivered using traditional, online, blended, and web enhanced course delivery formats at Miami Dade College, a large open access 4-year state college located in Miami-Dade County, Florida, was analyzed. A factorial ANOVA using course type, course delivery method, and student SES found no significant differences in final course grades when used to determine if course delivery methods were equally effective for students of low and not low SES taking STEM course types. Additionally, three chi-square goodness-of-fit tests were used to investigate for differences in enrollment, course completion and course passing status by SES, course type, and course delivery method. The findings of the chi-square tests indicated that: (a) there were significant differences in enrollment by SES and course delivery methods for the Engineering/Technology, Math, and overall course types but not for the Natural Science course type and (b) there were no significant differences in course completion status and course passing status by SES and course types overall and SES and course delivery methods overall. However, there were statistically significant but weak relationships between course passing status, SES and the math course type as well as between course passing status, SES, and online and traditional course delivery methods.
The mixed findings in the study indicate that strides have been made in closing the theoretical gap in education and technology skills that may exist for students of different SES levels. MDC’s course delivery and student support models may assist other institutions address student success in courses that necessitate students having some level of technology fluency
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The Management of Context in the Machine Learning Lifecycle
We present novel techniques and systems for managing data context within the machine learning (ML) lifecycle. Drawing from a vision laid out in 2018, we present Flor and its evolutions, FlorDB and FlorDB with Build extensions, designed for comprehensive metadata capture and version control in the ML lifecycle. A cornerstone of our approach is the use of an interview study to understand what the ML lifecycle is, and how engineers operationalize machine learning, focusing on MLOps and the iterative model development process. Through the implementation of these systems and their use in real-world applications for lawyers and journalists, we demonstrate the tangible benefits of rich data context in agile model development. In sum, we show how the integration of Application, Build, and Change contexts—The ABCs of Context—enables MLEs to close the loop in the ML lifecycle
Estrategia integral urbana para las reconversiones portuarias y el hacer ciudad; plan-proyecto y diseño-ejecución
Esta ponencia, se desarrolla en el contexto de los resultados y conclusiones de la tesis doctoral
en etapa final de desarrollo, Los procesos de Transformación de suelos portuarios en suelos
urbanos, una gestión para la regeneración de la ciudad, el caso del nuevo uso de suelo
portuario en Valparaíso, desarrollada por el autor y dirigida por la co-autora. Se pretende
presentar de manera sintética los aspectos finales de la tesis, que desarrollan una estructura
de gestión para los procesos de reconversión portuaria, desde una perspectiva integral, que
considere desde la planificación-ordenación (plan-proyecto) hasta la ejecución-gestión de las
zonas portuarias obsoletas convertidas en zonas urbanas. Entendiendo que este proceso debe
abarcar un periodo temporal de largo recorrido, desde la identificación de las zonas a
reconvertir hasta la posible gestión económica de las zonas transformadas. Asimismo el
proceso debe incorporar la participación obligada en la planificación, de la administración local
(e incluso la sectorial involucrada), así como al privado y la sociedad, entendida esta última
como agente de control del procesos, pero también como posibilitador, en tanto se han
descubierto mecanismos viables de aportación monetaria por parte de la ciudadanía, situación
que los involucra directamente en los procesos y los valida más como agentes de control.
En una primera parte se presentará la importancia de las zonas portuarias “en y para” las
ciudades y desde una perspectiva histórica breve se plantearán los desafíos de éstas. “La
contribución de los puertos marítimos al desarrollo de las ciudades es un hecho que se ha
venido observando a lo largo de la historia. Las instalaciones portuarias han promovido desde
siempre el comercio, la pesca, la técnica, las relaciones con otras culturas...” (ALEMANY, 2003)
En una segunda parte se presentarán de manera muy breve algunos de los aspectos básicos
de la investigación que han conducido al desarrollo de la propuesta de estructura de gestión,
desde una perspectiva teóricas, considerando algunos de los conceptos involucrados, como
waterfront, marketing urbano, skylines e imagen de ciudad, entre otros. Para continuar con los
procesos y las incidencias que las administraciones han tenido y deben en tener en la toma de
decisiones referidas a estas transformaciones. “En la temática del Waterfront Redevelopment
incide la innovación tecnológica y logística y el cambio de la percepción de la posición pública.”
(HAYUT, 1994)
Finalmente en una tercera parte se presenta el modelo o estrategia integral, en base a los
aspectos previos, relacionándolos con el conjunto de experiencias analizadas, desde las que
se extraen los elementos esenciales de una estrategia y presentando un esquema conceptual y operativo de una estructura integral. De esta última se extraen unas conclusiones a modo de
síntesis del procesoPeer Reviewe
Reconversiones portuarias y waterfronts: Valparaíso y Río de Janeiro ¿utopía o realidad?
Existen diversos estudios acerca de los procesos de reconversión portuaria y de sus frentes marítimos o “waterfronts” sobre todo en el sentido de la conjugación de los intereses de la colectividad y de los privados por las presiones económicas existentes sobre estos suelos, que liberados de sus usos portuarios o industriales anteriores, pasan a tener disponibilidad urbana. Estas operaciones que han comenzado hace ya más de medio siglo tienen sus grandes referentes en Europa y América del norte, sin embargo Puerto Madero en Buenos Aires ha sido también paradigmático en la recuperación de una zona previamente deteriorada y obsoleta de la ciudad. Una de las grandes cuestiones de estos procesos es la compatibilización del interés público y el privado, por eso es interesante investigar, como nuestras ciudades latinoamericanas se plantean la gestión y desarrollo de estos procesos. Valparaíso y Río de Janeiro han realizado en esta última década esfuerzos por materializar procesos en este sentido y estos son objeto de esta ponencia.Peer Reviewe
Diseño de investigación de un modelo experimental factorial en la identificación del nivel de influencia de los factores de producción que afectan el rendimiento de la mezcla de vegetales congelados en una empresa de alimentos de el tejar, Chimaltenango
Plantea la aplicación del diseño de experimentos en la modalidad experimental factorial para la identificación del nivel de influencia que tienen los factores de producción involucrados en la elaboración del producto que afectan el rendimiento productivo en la mezcla de vegetales congelados en una empresa de alimentos de El Tejar, Chimaltenango
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The Importance of the Montreal Protocol in Mitigating the Potential Intensity of Tropical Cyclones
The impact of the Montreal Protocol on the potential intensity of tropical cyclones over the next 50 years is investigated with the Whole Atmosphere Community Climate Model (WACCM), a state-of-the-art, stratosphere-resolving atmospheric model, coupled to land, ocean, and sea ice components, with interactive stratospheric chemistry. An ensemble of WACCM runs from 2006 to 2065 forced with a standard future scenario is compared to a second ensemble in which ozone-depleting substances (ODS) are not regulated (the so-called World Avoided). It is found that by the year 2065, changes in the potential intensity of tropical cyclones in the World Avoided are nearly 3 times as large as for the standard scenario. The Montreal Protocol thus provides a strong mitigation of the adverse effects of intensifying tropical cyclones.
The relative importance of warmer sea surface temperatures (ozone-depleting substances are important greenhouse gases) and cooler lower-stratospheric temperatures (accompanying the massive destruction of the ozone layer) is carefully examined. It is found that the former are largely responsible for the increase in potential intensity in the World Avoided, whereas temperatures above the 70-hPa level—which plunge by nearly 15 K in 2065 in the World Avoided—have no discernible effect on potential intensity. This finding suggests that the modest (compared to the World Avoided) tropical ozone depletion of recent decades has not been a major player in determining the intensity of tropical cyclones, and neither will ozone recovery be in the coming half century
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