A Survey of the Spacecraft Line-Of-Sight Jitter Problem

Predicting, managing, controlling, and testing spacecraft Line-of-Sight (LoS) jit- ter due to on-board internal disturbance sources is a challenging multi- disciplinary systems engineering problem, especially for those observatories hosting extremely sensitive optical sensor payloads with stringent requirements on allowable LoS jitter. Some specific spacecraft jitter engineering challenges will be introduced and described in this survey paper. Illustrative examples of missions where dynamic interactions have to be addressed to satisfy demanding payload instrument LoS jitter requirements will be provided. Some lessons learned and a set of recommended rules of thumb are also presented to provide guidance for analysts on where to initiate and how to approach a new spacecraft jitter design problem. These experience-based spacecraft jitter lessons learned and rules of thumb are provided in the hope they can be leveraged on new space system development projects to help overcome unfamiliarity with previously identified jitter technical pitfalls and challenges

Agency, Liberation, and Intersectionality among Latina Scholars: Narratives from a Cross-institutional Writing Collective

Among United States residents, the number of doctoral degrees conferred to Latinx students represents a small percentage compared to other groups. For example, from 2009–2010, the percentage of degrees conferred to Latinx students was 5 percent compared to 74 percent for White students, 11 percent for Asian/Pacific Islanders, 7 percent for African Americans, and 0.7 percent for Indian/Alaska Natives. During the same period, the proportion of doctoral degrees conferred to females was 55 percent for Latinas compared to 65 percent for African American students, 56 percent for Asian/Pacific students, 54 percent for American Indian/Alaska Native students, and 51 percent for White female students (National Center for Education Statistics). Historically, underrepresented minority (URM) students encounter a plethora of issues that influence their educational experiences, yet there is a scarcity of scholarship that elucidates the quality of experience of women of color (WOC) pursuing doctorate degrees (Aryan and Guzman). As multi-marginalized, firstgeneration college students, we continuously struggle to find a place within higher education. Our educational pathways to becoming doctoral recipients have occurred primarily within the context of alienation, significantly influencing our need to connect with other WOC who have also felt isolated and disconnected. Consequently, we needed to find each other because knowing that there were other Latinas in doctoral programs, and actually getting to know them, validated our existence within academiaUniversity Writing Cente

The Fuzzy Boundaries in Start-up Firms Industries. A Social Network Analysis

This paper aims to explore and describe the way in which start-up firms are grouped into industries. To this end, a quantitative research approach is presented, applying a social network analysis to a sample of Pacific Alliance start-ups, which were recorded in CrunchBase, considering their operational activities as linkage criteria. In this way, this document offers a new application to social network analysis to demonstrate the need for a different way of classifying start-ups that goes beyond the industry boundaries established by the traditional classification systems. It also shows that Pacific Alliance start-up industries are structured according to a pattern of dominant activity, applied technology and specific use. In addition, there is a concentration on mature or declining start-up industries, while growing industries are left in second order

Vacuum stability conditions of the economical 3-3-1 model from copositivity

By applying copositivity criterion to the scalar potential of the economical $3-3-1$ model, we derive necessary and sufficient bounded-from-below conditions at tree level. Although these are a large number of intricate inequalities for the dimensionless parameters of the scalar potential, we present general enlightening relations in this work. Additionally, we use constraints coming from the minimization of the scalar potential by means of the orbit space method, the positivity of the squared masses of the extra scalars, the Higgs boson mass, the $Z'$ gauge boson mass and its mixing angle with the SM $Z$ boson in order to further restrict the parameter space of this model.Comment: 22 pages, 7 figures, added text and references. Matches published versio

Spacecraft Micro-Vibration: A Survey of Problems, Experiences, Potential Solutions, and Some Lessons Learned

Predicting, managing, controlling, and testing spacecraft microvibrations due to on-board internal disturbance sources is a formidable multi-disciplinary systems engineering challenge, especially for those observatories hosting extremely sensitive optical sensor payloads with stringent requirements on allowable line-of-sight jitter. In this paper some specific spacecraft micro-vibration engineering challenges will be introduced and described. Technical background context is provided with the inclusion of several illustrative examples of NASA and European Space Agency missions (both past and present) where dynamic interactions have to be addressed and which have demanding payload instrument line-of-sight jitter requirements. A general modeling, analysis, simulation, and test approach to address and solve the overall problem of spacecraft micro-vibrations is outlined. Recommended rules of thumb are presented to provide guidance for analysts on where to initiate and how to approach a new spacecraft micro-vibration design problem. A set of experience-based spacecraft micro-vibration lessons learned are also presented in the hope they can be leveraged on new system development projects to help overcome unfamiliarity with previously identified microvibration technical pitfalls and challenges

Metodología para el desarrollo de aplicaciones web ajustada al contexto de los Productos Mínimos Viables

El sector de las Tecnologías de la Información y Comunicación ha sido identificado como un foco de desarrollo para la economía. Se impulsan iniciativas para la creación de negocios en este ramo, las cuales en su mayoría presentan limitaciones en recursos, experiencia y conocimiento. Es por ello que se hace necesaria una ejecución efectiva del proceso. Este artículo formula una metodología para el desarrollo de aplicaciones web como Producto Mínimo Viable (PMV), así como destaca el papel que desempeñar el Software Libre el cual, por sus características, puede soportar el proceso de manera efectiva

Metodología para el desarrollo de aplicaciones web ajustada al contexto de los Productos Mínimos Viables

El sector de las Tecnologías de la Información y Comunicación ha sido identificado como un foco de desarrollo para la economía. Se impulsan iniciativas para la creación de negocios en este ramo, las cuales en su mayoría presentan limitaciones en recursos, experiencia y conocimiento. Es por ello que se hace necesaria una ejecución efectiva del proceso. Este artículo formula una metodología para el desarrollo de aplicaciones web como Producto Mínimo Viable (PMV), así como destaca el papel que desempeñar el Software Libre el cual, por sus características, puede soportar el proceso de manera efectiva

Hacia la construcción de una propuesta analítica para el estudio de las redes de colaboración: CIENCIA ergo sum

El objetivo del trabajo es mostrar la construccion y desarrollo de una prpueta que permita el el estudio de las redes de colaboración científica a partir de revistas científicas, tomando como caso la revista CIENCIA ergo sum. Se toma el artículo como referencia para el análisis de la comformacióin de redes, es decir, la visualización de los mecanismos de de interacción y cooperación entre investoigadores provenientes de diferentes ambitos institucionales y nacionales para la producción del conocimento

“Exploring academic English writing skills in pre-service teachers for professional development”

Academic writing is a skill that allows develop in the academic and professional environment. To master this skill requires knowledge about skills and concepts that help in written production. However, writing and especially academic writing has been a problem in the academic development of students, especially in the eighth level students of the English course at the Technical University of Cotopaxi. These students have difficulty in mastering academic vocabulary, connectors of ideas and, especially, difficulty in organizing their ideas. All the difficulties mentioned above have been reflected in their level of academic writing when presenting their essays. Therefore, the objective of this research is to determine the skills to develop academic English writing in pre-service teachers for professional development. The methodology used in this project is qualitative and descriptive because it explains and describes the main problems that pre-service teachers present in academic writing texts. The results reflect that indeed the pre-service teachers possess a low level of academic writing skills. The researchers identified that the analysis of the writing results was low of clarity in texts, poor context sentences, as well as inadequate application of English as a second language because they use translator.La escritura académica es una habilidad que permite desarrollarse en el ámbito académico y profesional. Para dominar esta habilidad se requiere conocer las habilidades y conceptos que ayudan a la producción escrita. Sin embargo, la escritura y especialmente la escritura académica ha sido un problema en el desarrollo académico de los estudiantes, especialmente en los alumnos de octavo nivel de la carrera de inglés de la Universidad Técnica de Cotopaxi. Estos estudiantes tienen dificultad en el dominio del vocabulario académico, conectores de ideas y, especialmente, dificultad en la organización de sus ideas. Todas las dificultades mencionadas anteriormente se han visto reflejadas en su nivel de escritura académica al presentar sus ensayos. Por lo tanto, el objetivo de esta investigación es determinar las habilidades para desarrollar la escritura académica en inglés en profesores en formación para su desarrollo profesional. La metodología utilizada en este proyecto es cualitativa y descriptiva porque explica y describe los principales problemas que presentan los docentes en formación en los textos de escritura académica. Los resultados reflejan que, efectivamente, los profesores en formación poseen un bajo nivel de habilidades de escritura académica. Los investigadores identificaron que el análisis de los resultados de la escritura fue de baja claridad en los textos, oraciones pobres en el contexto, así como una inadecuada aplicación del inglés como segunda lengua porque utilizan el traductor