A propósito del voseo: su historia, su morfología y su situación en Costa Rica

La enseñanza y aprendizaje de la lengua materna, dentro de un contexto social, involucra, también, el entorno cultural. En este marco, se pretende, en concreto, un aporte a la capacitación de los docentes y las docentes en lo relativo al estudio diacrónico y sincrónico de la lengua española, en específico, a las formas de tratamiento de segunda persona singular, enfatizando en el paradigma de conjugación del voseo; se persigue tomar conciencia de que hay que valorar el dialecto propio, como medio de identidad socio- cultural, y en el hecho de que el empleo de vos no implica para nada una corrupción de la lengua y que no es un fenómeno circunscrito a Costa Rica, sino que es general a la América hispanohablant

확률적 열화학 점탄성 모델을 적용한 탄소섬유 강화 적층 복합재료의 가상 RTM제조 시뮬레이션

학위논문 (석사) -- 서울대학교 대학원 : 공과대학 항공우주공학과, 2020. 8. 윤군진.Composite materials undergo a shrinkage process related to the curing kinetics of the matrix. This shrinkage effect, added to the material thermal expansion, results in geometric distortions and residual interlaminar stresses that affect negatively the mechanical response of the materials. This work addresses the effects of the manufacturing process on carbon fiber reinforced composite laminates used in aerospace structures. Here, computational tools are implemented to model a viscoelastic material with degree of cure and time-dependent properties. Additionally, probabilistic modeling tools are implemented in the interest of increasing the reliability of the results by considering the random nature of curing kinetics parameters. The model consists of a multiphysics system that couples the thermochemical and mechanical processes. First, the heat transfer analysis is performed by relating Fouriers heat conduction governing equations with Kamals model of curing kinetics. Then, for the mechanical analysis, a 9-element Generalized Maxwell Model is implemented to compute the viscoelastic behavior. The representation of a cure and time-dependent viscoelastic model is possible due to the thermorheologically simple nature of the thermosetting resins. Here, a shift factor is applied to obtain stress relaxation times that change with the temperature and the degree of cure of the material. To produce the stochastic behavior of the materials, random fields were created by implementing the Karhunen-Loève Expansion method with a Monte Carlo simulation. The manufacturing method consisted of a vacuum-assisted transfer molding (VARTM) with a post-curing treatment. To emulate this process, the mechanical and thermal boundary conditions are divided into four stages. The first one refers to the curing stage. Here, the plate is constrained in the mold and subjected to thermal conduction in the surfaces. The second stage is when the plate is released from the mold and left to cool down to room temperature by natural convection. The third stage consists of placing the cooled plate into an oven (forced thermal convection). Finally, the plate is left to cool down as in the second stage. The stress and distortions that result from this manufacturing process were analyzed in six plates with different ply configurations. The results showed that the quasi-isotropic laminate [−60/−30/0/30/60/90] undergoes the highest interlaminar stresses and distortions, followed by the asymmetric cross-ply laminate[903/03] . tt also revealed that the post-curing process increases the interlaminar residual stresses in most of the laminates, especially in the case of the antisymmetric angle ply laminate. The effect of the cure dependent viscoelastic model is then compared to a basic linear elastic material response. Revealing that a viscoelastic model predicts higher stresses during the curing stage (in-mold plates) but lower stresses once the plates are released from the molds. Finally, the effects of taking into account the random nature of the curing kinetics parameters were observed in the curing stage of a cross-ply laminate. This analysis revealed that the stresses can be 23.86% higher than the values predicted from a viscoelastic model that ignores this effect. Demonstrating the importance of considering the random nature of the properties involved in the curing process.복합 재료는 매트릭스(matrix)의 경화 속도에 관련된 수축 과정을 거친다. 재료 열팽창에 더해지는 이러한 수축 효과는 재료의 기계적 성능에 부정적인 영향을 미치는 기하학적 비틀림과 잔류 층간 응력을 초래한다. 본 연구는 항공 우주 구조물에 사용되는 탄소 섬유 강화 복합재료 라미네이트(laminate)에 제조 공정이 미치는 영향을 분석한다. 여기서, 경화 정도 및 시간 의존적 특성을 갖는 점탄성 재료를 모델링하는 컴퓨터 시뮬레이션 툴이 구현된다. 또한, 결과의 신뢰성을 높이기 위해 경화 동역학 파라미터의 랜덤 특성을 고려하는 확률론적 모델이 구현된다. 이 모델은 열화학 및 기계 공정을 결합하는 다중 물리 시스템으로 구성된다. 먼저, 열전달 해석은 FourierFourier의 열전도 지배 방정식과 Kamal의 경화 동역학 모델을 통해 수행된다. 그런 다음 점탄성 거동을 나타내기 위해 아홉개의 요소(9-element)로 일반화 된 Maxwell 모델이 구현된다. 재료모델이 경화 모델과 점탄성 모델 만으로 표현될 수 있는 이유는 열경화성 수지가 열/유동학적으로 간단한 성질을 가지기 때문이다. 여기서, 재료의 온도 및 경화 정도에 따라 변화하는 응력 완화 시간을 얻기 위해 환산 인자(shift factor)가 적용된다. 재료의 확률론적 거동을 나타내는 랜덤 필드(random field)는 Monte Carlo 시뮬레이션으로 Karhunen-Loève Expansion 방법을 구현하여 만들어진다. 이번 연구에서 모델링하는 제조 공정은 진공 레진 전달 몰딩(vacuumvacuum--assisted transfer molding, assisted transfer molding, VARTM)과 그 후처리 과정으로 구성되었다. 이 공정을 모방하기 위한 열기계적 경계 조건은 4 단계로 나뉜다. 첫 번째는 경화 단계이다. 여기서 플레이트는 몰드(mold)에 구속되고 몰드 표면에서 열 전도가 일어난다. 두 번째 단계는 플레이트가 몰드에서 분리되어 대류에 의해 상온으로 냉각되는 상태이다. 세 번째 단계는 냉각된 플레이트를 오븐(강제 열 대류)에 넣는 것이다. 마지막으로, 플레이트는 두 번째 단계에서와 같이 냉각되도록 방치된다. 이 제조 공정에서 발생하는 응력과 비틀림은 플라이 구성이 다른 6 개의 플레이트에 대해 분석되었다. 시뮬레이션 결과 준 등방성 라미네이트 [-60 / -30 / 0 / 30 / 60 / 90]가 가장 높은 층간 응력과 비틀림을 겪었고 그 다음으로는 비대칭 크로스-플라이(cross-ply) 라미네이트[903/03] 가 높은 층간 응력과 비틀림을 기록했다. 또한, 후처리 공정은 대부분의 비대칭 앵글 플라이(angle ply) 라미네이트에서 층간 잔류 응력을 증가시키는 것으로 밝혀졌다. 경화 의존 점탄성 모델의 타당성은 선형 탄성 재료모델과의 비교를 통해 검증된다. 점탄성 모델은 선형 탄성 모델에 비해 경화 단계에서는 더 높은 응력을 예측하지만 플레이트가 몰드에서 분리되면 더 낮은 응력을 보여준다. 마지막으로, 경화 동역학 파라미터의 랜덤 특성을 고려함에 따른 효과는 크로스-플라이 라미네이트의 경화 단계에서 관찰되었다. 랜덤 특성을 고려한 모델은 이 효과를 고려하지 않은 모델에 비해서 최대 23.86% 더 높은 응력을 가질 수 있음이 관측되었다. 이는 경화 공정과 관련된 랜덤 특성을 고려하는 것이 복합재료 경화 공정을 해석하는 데에 매우 중요 함을 보여준다.Chapter 1. Introduction 1 1.1 Aerospace Industry Materials 2 1.2 Composite Materials 4 1.3 Manufacture of Composite Materials 6 1.4 Previous Research 9 1.5 Thesis Structure 10 Chapter 2. Literature Review 11 2.1 Thermochemical Model 11 2.2 Viscoelastic Model 14 2.2.1 Analog Mechanical Models 15 2.2.2 Multiple Element Models 20 2.2.3 Generalized Kelvin Model 21 2.2.4 Generalized Maxwell Model 22 2.3 Cure and temperature dependence 24 2.4 Random Field Modeling 28 2.4.1 Orthogonal Series Expansion 29 2.4.2 Karhunen-Loève Expansion 31 2.4.3 Parameters to be randomized 33 2.5 Classical Lamination Theory 34 Chapter 3. Materials and Methodology 36 3.1 Materials 36 3.2 Methodology 40 3.3 Experimental Setup 44 Chapter 4. Model Verification 46 Chapter 5. Results 50 5.1 Residual stress comparison 50 5.2 Cure-induced distortion 53 5.3 Curing-induced distortions coupling effects 58 5.4 Post curing-induced stress and distortion 64 5.5 Viscoelasticity Effects 66 5.6 Random Field Distribution 68 5.7 Experimental Results 73 6. Conclusions 78 Bibliography 81 Appendix 91 Appendix A. Laminate Stiffness Matrix 91 Appendix B. Thermochemical analysis code 93Maste

The influence of gender beliefs and early exposure to math, science and technology in female degree choices

This research consists of three sections testing the hypothesis that gender roles and gender-stereotyping of certain fields of study could be associated with women choosing traditionally female degree options characterized by lower wages. The analysis is framed within the identity economics framework. In the first chapter, data from the 1970 British Cohort Study supports the hypothesis that teenage girls are more likely to accept gender-equal beliefs when their mother shares these beliefs or she works; and that having gender equal beliefs and developing early mathematical and technological skills either encourage girls to study for high-paying degrees or discourage them from entering female-dominated degrees. The second chapter analyses the responses from an online questionnaire applied to female academics at the University of York. Such survey collected testimonies about their experiences regarding the construction of gender, encouragement and discouragement in mathematics, science and technology at school and the household environments; and their degree choice. Results provide some evidence in favour of the initial hypothesis, but they also show a disassociation between how women perceive the sex-typing of subject fields and their own confidence in their capabilities and tastes. It also suggests that bad experiences with certain subjects are more relevant in keeping women away from high-earnings degrees than the lack of positive experiences. Finally, the third chapter estimates earnings functions and provides a gender wage decomposition using data from the 1970 British Cohort Study at ages 29 and 34. Results do not support the hypothesis that having a high-earnings degree is associated with higher wages for women. Although there is an initial premium, it disappears by age 34. In contrast, working in a high-earnings occupation is positively associated with higher wages, while remaining in female-dominated occupations is negatively associated with wages for women

Percepción de las mujeres miskitas sobre el Liwa en Wasla, Waspam, río Coco

In this research, we have determined the perception that the Miskitu indigenous women from the community of Wasla has about the Liwa or spirit of the waters. It is a qualitative study based on an ethnographic design, in which we applied interviews to 30 miskitu women from the community of Wasla, Waspam. Among the most important findings, we can highlight that these women believe in the existence of Liwa and this belief affects the people’s health, especially in pregnant women and children. Also the most frequent discomforts and pains that the women present are: pain in the lower abdomen, transvaginal bleeding, itching and vaginal flow, spots on the skin and early miscarriage. The conclusion indicates that is necessary the recognition of traditional medicine and its articulation with western medicine in order to improve the health care quality in the municipality.En este estudio se ha determinado la percepción que tienen las mujeres indígenas miskitas sobre el Liwa o espíritu de las aguas en la comunidad de Wasla. Es un estudio cualitativo sustentado en diseño etnográfico donde aplicó una entrevista a 30 mujeres del grupo étnico Miskitu pertenecientes a la comunidad Wasla, Waspam. Entre los hallazgos más importantes se destacan que: las mujeres creen en la existencia del Liwa y este afecta sobre la salud de las personas, más en mujeres embarazadas y niños; y los malestares más frecuentes que presentan las mujeres son: dolor en bajo vientre, sangrado transvaginal, picazón y flujo vaginal, manchas en la piel y aborto prematuro. Se concluye, que es necesario el reconocimiento de la de la medicina tradicional y la articulación con la medicina occidental para mejorar la calidad de la atención en salud del municipio

Safety Program for the assembly and disassembly processes of Trópika, habitation module, in the Solar Decathlon 2014 competition

Proyecto de Graduación (Bachillerato en Ingeniería en Seguridad Laboral e Higiene Ambiental) Instituto Tecnológico de Costa Rica, Escuela de Ingeniería en Seguridad Laboral e Higiene Ambiental, 2014.This project was made for the participation of Team Tec (Tech Team Costa Rica) in intercollegiate competition, Solar Decathlon Europe (SDE), France 2014. In this competition 20 universities from around the world must design, build and test a housing module that works with solar energy and must be sustainable. The organization of the SDE requires compliance with European safety standards, which have a higher level than the ones in Costa Rica. To meet the level of security that should be, was defined as a general objective to propose a Safety Program for the assembly and disassembly process of the Trópika, habitation module proposed by Tec Team for the competition. In order not only to meet the requirements of the organization, but also to strengthen the safety of team members. Among the main results are the following: During assembly the members of the team will be exposed to activities that involve risks with extreme level. Any team member has experience about construction works, which increase the risk of accident or incident. The knowledge of the team members in construction safety matters is deficient. SDE organization requires higher level of safety during all the stages of the project but especially during the assembly and disassembly process. In response to the above a Safety Program for the assembly and disassembly of Trópika was developed, incorporating safety aspects that should be followed during these processes, safe work procedures in order to guide the team members in the work was prepared to be conducted. It also contains a training plan and an emergency plan. With this tool Tec Team is benefited mainly to have a guide document to perform the work of more securely way which helps to protect and care for the integrity of the team members.Instituto Tecnológico de Costa Ric

Variaciones anatómicas del arco aórtico en una muestra de población Colombiana

Introducción. El arco aórtico (AA) es el origen de estructuras vasculares que suplen los miembros superiores y el encéfalo. Se han descrito hasta ocho diferentes tipos de distribución con implicaciones clínicas y quirúrgicas. Objetivo. Determinar la frecuencia de las variaciones anatómicas del AA y establecer los diámetros vasculares de sus ramas emergentes en una muestra de población colombiana. Materiales y métodos. Se realizó un estudio descriptivo analítico transversal mediante disección de 35 plastrones cervicotorácicos obtenidos con muestreo a conveniencia. Resultados. La distribución de los AA resultó muy similar a la reportada en Colombia y otros países, siendo más frecuente el AA Tipo I seguido del AA Tipo II o arco bovino. Los diámetros vasculares arrojaron resultados análogos a otros obtenidos en población colombiana, pero medias evidentemente menores a las reportadas en estudios internacionales. Conclusión. Aunque las frecuencias de los tipos de AA de la población colombiana resultan ser similares a las de otros países, los diámetros vasculares en Colombia son menores.ntroduction: The aortic arch (AA) is the origin of the vascular structures that supply the upper limbs and the brain. Up to eight different types of distributions have been described with clinical and surgical implications. Objective: To determine the frequency of anatomical variations of the AA, and to establish the vascular diameters of its branches in a sample of Colombian population. Materials and methods: A descriptive cross-sectional study was conducted by dissecting 35 cervicothoracic grafts obtained through convenience sampling. Results: The distribution of AA was similar to that reported in Colombia and other countries, being Type I the most frequent, followed by Type II or bovine arch. The vascular diameters showed results similar to those obtained in the Colombian population, but evidently lower than those reported in international studies. Conclusion: Although the frequency of AA types in the Colombian population happen to be similar to those in other countries, the vascular diameters in Colombia are smaller

Posible asociación entre alta sospecha de apnea obstructiva del sueño, fenotipo craneofacial y de vías aéreas superiores en niños de 6 a 18 años con fisura labiopalatina no sindrómica postcirugía

Se tomaron radiografías laterales a 51 niños con corrección de FLPNS que fueron comparadas con 19 niños sin FLPNS con AOS y 25 niños sin FLPNS y sin AOS. El diagnóstico de AOS en el grupo control se realizó mediante polisomnografía. La edad de la población osciló entre 6 y 18 años. El diagnóstico de alta sospecha de AOS se realizó mediante la aplicación del cuestionario pediátrico de trastornos del sueño. Se emplearon pruebas estadísticas X2, prueba exacta de Fisher, U-Mann Whitney y OR. Resultados: En el grupo sin FLPNS con AOS se observó disminución del espacio de la vía aérea inferior en un 52.6% comparado con 29.4% en el grupo con FLPNS y 24% en el grupo sin FLPNS y sin AOS (p=0.04). En el grupo control sin apnea ningún sujeto presentó una posición inferior del hueso hioides respecto a plano mandibular, mientras que 11 pacientes del grupo con FLPNS sí presentaron dicha posición (p=0.006). Se observó una posición anterior del hueso hioides respecto a la tercera vértebra cervical en un 4% del grupo control sin apnea comparado con el 31.4% de los casos con FLPNS (p=0.002).Conclusión: Los resultados sugieren que los pacientes con FLPNS presentan características fenotípicas en la posición del hueso hioides que los hacen más susceptibles de presentar AOS, sin embargo se deben realizar futuros estudios para determinar si esta susceptibilidad es inherente a la patología, o es resultado de las secuelas quirúrgicas.Lateral x-rays were taken in 51 children with corrective surgery for cleft and lip palate. Cephalometrics measurements in this case group were compared with cephalometrics measurements obtained from 19 non NSCLP children with OSA and 25 children without OSA diagnosed by polisomnography. The age oscillate between 6 and 18 years. The diagnosis for suspected obstructive sleep apnea was made trough pediatric sleep questionnaires. X2, Fisher, U-Mann Whitney and OR were used for statistical analysis. Results: A decrease size of the lower airway was found in 52,6% of control OSA group compared with 29,4% of NSCLP group and 24% of control without OSA (p=0.04) None of the patients in Control without OSA group had a lower position of hyoid bone compared with 11 patients in NSCLP group (p=0.006). An anterior hyoid bone position was found in 4% of Control without OSA group compared with 31.4% of NSCLP patients (p=0.002). Conclusions: The results of this study suggest that NSCLP had phenotypic features in hyoid bone position making them more susceptible for OSA, however future studies should be done to determine if this susceptibility is inherent to the pathology or if is the result of surgical seculae.Especialista en OrtodonciaEspecializació

Compact Modeling Technique for Outdoor Navigation

16 pages, 46 figures.In this paper, a new methodology to build compact local maps in real time for outdoor robot navigation is presented. The environment information is obtained from a 3-D scanner laser. The navigation model, which is called traversable region model, is based on a Voronoi diagram technique, but adapted to large outdoor environments. The model obtained with this methodology allows a definition of safe trajectories that depend on the robot's capabilities and the terrain properties, and it will represent, in a topogeometric way, the environment as local and global maps. The application presented is validated in real outdoor environments with the robot called GOLIAT.This work was supported by the Spanish Government through the MICYT project DPI2003-01170.Publicad