Creation of a trajectory framework that could be sustainable for a continuous exploration of Mars and its moons

As humanity looks to the Cislunar region in recent space flight operations, the question remains: where will technology advance next? Mars is of particular interest with both the public and private sector aiming to get humans on the planet in the coming decades. Investigating stable trajectories in the Mars-Phobos-Deimos system for telecommunications and observation is the next step in developing future mission plans. Innovations in orbital mechanics must be considered, neither the Two Body Problem (2BP) nor the Circular Restricted Three Body Problem (CR3BP) are sufficient to effectively model satellite motion. Instead, in similar fashion to the patched-conics solution of transfers between the influence of celestial bodies, a patched CR3BP-2BP-CR3BP method of propagating the orbits is proposed. To begin, assumptions about Deimos and Phobos will be made—co-planar orbits and spherical symmetry to name a few. Once the problem has been successfully modeled, each assumption will be undone methodically to increase modeling accuracy. Impulsive maneuvers will be considered, as well as low, continuous thrust maneuvers. The aim of this project is to develop a robust, sustainable trajectory framework that can be used in future missions

Resolución de conflictos al interior de las organizaciones de usuarios de aguas en Chile: ¿judicialización o arbitraje?

Las alternativas o vías utilizadas actualmente para la solución de conflictos, esto es, la judicialización o el arbitraje no serían aparentemente los únicos caminos existentes para la resolución de las controversias de carácter trascendente para los usuarios de los cauces. En efecto, por una parte creemos que no obtendremos nada productivo si el legislador continúa agregando nuevos procedimientos, tanto para los arbitrajes como para los procesos propiamente judiciales. Esto se debe a que si estos nuevos procedimientos se utilizan diariamente, no cumplen con los fines esperados. Para abordar y solucionar la situación planteada creemos del todo factible que sean las Juntas de Vigilancia las que, utilizando al Directorio como árbitro arbitrador, resuelvan en primera instancia, como lo hacen en la actualidad, los conflictos surgidos en todo su territorio

Toward Eco-centric, Earth-as-School, and Love-based Curriculum and Learning: Example of a graduate course

This article puts forward love, care, and reverence for all people and our nonhuman kin as the center of posthumanist education. Opening our spiritual eye and building intimate relationships with nature and with all elements of the universe is envisioned as part of a schooling or post-schooling experience; our body, heart and spirit, along with our mind, is an essential part of learning. The article describes the experiences of students taking a graduate level course focusing on global climate change and education at a university in the United States. We use the course as an example to explore what posthumanist education entails. In this qualitative study, students taking the course, along with the faculty designing and teaching the course, describe the course curriculum and pedagogies and reflect on the course’s impact on them. Data sources include the syllabus, students’ reflection papers, nature contact journals, final projects, art works, and group conversations. Although situated in North America, the article is rich with international perspectives as student authors came from six different countries. The article posits that posthumanist education must be eco-centric and love-based, engaging students’ whole being to feel for and love Mother Nature. Keywords: curriculum, education, nature, posthumanism, climate change, higher education, teaching and learning, contemplative pedagogies, spirituality &nbsp

Invariant vector fields and the prolongation method for supersymmetric quantum systems

The kinematical and dynamical symmetries of equations describing the time evolution of quantum systems like the supersymmetric harmonic oscillator in one space dimension and the interaction of a non-relativistic spin one-half particle in a constant magnetic field are reviewed from the point of view of the vector field prolongation method. Generators of supersymmetries are then introduced so that we get Lie superalgebras of symmetries and supersymmetries. This approach does not require the introduction of Grassmann valued differential equations but a specific matrix realization and the concept of dynamical symmetry. The Jaynes-Cummings model and supersymmetric generalizations are then studied. We show how it is closely related to the preceding models. Lie algebras of symmetries and supersymmetries are also obtained.Comment: 37 pages, 7 table

Invariant solutions of the supersymmetric sine-Gordon equation

A comprehensive symmetry analysis of the N=1 supersymmetric sine-Gordon equation is performed. Two different forms of the supersymmetric system are considered. We begin by studying a system of partial differential equations corresponding to the coefficients of the various powers of the anticommuting independent variables. Next, we consider the super-sine-Gordon equation expressed in terms of a bosonic superfield involving anticommuting independent variables. In each case, a Lie (super)algebra of symmetries is determined and a classification of all subgroups having generic orbits of codimension 1 in the space of independent variables is performed. The method of symmetry reduction is systematically applied in order to derive invariant solutions of the supersymmetric model. Several types of algebraic, hyperbolic and doubly periodic solutions are obtained in explicit form.Comment: 27 pages, major revision, the published versio

Resumption of elective colorectal surgery during COVID-19 and risk of death

Peer reviewedPostprin

An investigation of the disparity in estimates of microfilaraemia and antigenaemia in lymphatic filariasis surveys

The diagnosis of lymphatic filariasis (LF) is based typically on either microfilaraemia as assessed by microscopy or filarial antigenaemia using an immuno-chromatographic test. While it is known that estimates of antigenaemia are generally higher than estimates of microfilaraemia, the extent of the difference is not known. This dataset was produced as part of a literature review of surveys that estimate microfilaraemia and antigenaemia