Incorporation of trajectory behaviors in the vicinities of different planetary moons using Finite-Time Lyapunov Exponent Maps

There is an increasing interest in future space missions devoted to the exploration of key moons in the Solar system. These many different missions may involve libration point orbits as well as trajectories that satisfy different endgames in the vicinities of the moons. To this end, an efficient design strategy to produce low-energy transfers between the vicinities of adjacent moons of a planetary system is introduced that leverages the dynamics in these multi-body systems. Such a design strategy is denoted as the moon-to-moon analytical transfer (MMAT) method. It consists of a general methodology for transfer design between the vicinities of the moons in any given system within the context of the circular restricted three-body problem, useful regardless of the orbital planes in which the moons reside. A simplified model enables analytical constraints to efficiently determine the feasibility of a transfer between two different moons moving in the vicinity of a common planet. Additionally, Finite-Time Lyapunov Exponent (FTLE) maps within the context of the MMAT scheme are incorporated to enable direct transfers between moons that offer a wide variety of trajectory patterns and endgames, such as temporary captures, transits, takeoffs and landings. The resulting technique is demonstrated to be applicable to several mission scenarios

Orbit and Attitude Coupling in the Full Higher-Fidelity Ephemeris Model within the context of the Geometric Mechanics Framework

Predicting the orientation of spacecraft traveling within the Cislunar (Earth-Moon) region is necessary to ensure the success of future missions planned within that realm of space. This research looks to consider the coupling between translational and rotational motion to not only improve trajectory accuracy, but to also introduce the prediction of attitude in mission planning. Trajectories computed in the circular restricted full three-body problem (CRF3BP), previously proposed by the authors, allow for the spacecraft to be modeled as a rigid-body rather than a point mass. These trajectories are utilized as initial guesses for a full ephemeris model, where the gravitational field of perturbing bodies and the eccentricity of the Moon\u27s orbit alter these trajectories within this more complex dynamical environment. It has been shown through this research that attitude can be predicted in a full ephemeris model by the CRF3BP, a novel contribution to the field of astrodynamics research

Estrategias comunicativas del influencer "Henry Spencer" en la opinión pública de sus seguidores en Tik Tok, entre abril-mayo del 2022

La presente investigación tuvo como principal objetivo determinar las estrategias comunicativas del influencer Henry Spencer en la opinión pública de sus seguidores en la red social Tik Tok, periodo abril-mayo, 2022. Así mismo, el enfoque seleccionado fue el cualitativo, se aplicó la técnica de entrevista con el instrumento guía de entrevista. El instrumento tuvo participación de seis personas, dos de ellos fueron influencers del medio Tik Tok y las otras cuatro fueron seguidores de los contenidos de Henry Spencer. Para el análisis e interpretación de los datos obtenidos por la guía de entrevista, se utilizó el programa Atlas Ti, que lanzó resultados precisos por medio de gráficos que apoyaron a las conclusiones. Del análisis se obtuvo como resultado que los influencers logran conectar con un sector social que los necesita, se vuelve un líder de opinión que se convierte en el representante de su comunidad y se proclama el gestor de contenido que sirve de concilio y entretenimiento para sus seguidores. Finalmente, la conclusión de la investigación fue que las estrategias comunicativas del influencer utiliza un lenguaje globalizado para la mejor comprensión de sus mensajes, ganar confianza con su sencilla imagen y tocar temas actuales de la sociedad

Leveraging the Moon and stable Libration point orbits around L4/L5 to observe the Solar corona

There is a significant interest in studying the Solar corona to gather information about the Sun. This investigation provides an efficient approach to observe the So- lar corona by using the Moon as an occulter to suppress the blinding luminosity of the Sun’s surface. Another objective is an analysis and comparison of diffraction patterns created by Lunar occultations (LO) from L4 and from Earth. By exploit- ing the Libration point L4 within the Cislunar region, a spacecraft (s/c) would be within proper position to observe the Solar corona every sidereal month

Immersive Trajectory Design Framework Using Augmented Reality

The field of astrodynamics currently relies on highly specialized tools for spacecraft trajectory design, resulting in intricate trajectories sometimes difficult to visualize on 2D screens. On the other hand, the intuitive interaction capabilities of augmented reality make it ideal for solving complex 3D problems that require complex spatial representations, which is key for astrodynamics and space mission planning. By implementing common and complex orbital mechanics algorithms in augmented reality, a hands-on method for designing orbit solutions and spacecraft missions is created. This effort explores the aforementioned implementation with the Microsoft Hololens 2 as well as its applications in both industry and academia. Furthermore, the collaboration between the Human Factors and Aerospace Engineering departments led to the creation of a user-friendly augmented reality system tailored for space mission planning. A user-centered design approach was explored, which involved assessing user requirements, analyzing existing processes, prototyping an AR interface, and engaging in iterative design. Moving forward, the team plans to refine and test the application\u27s front-end design through heuristic evaluations, ongoing refinement, and testing of prototypes with potential users. This is all in hopes of ensuring that the tool is user-friendly, while maintaining accuracy and applicability to higher-fidelity problems

A review on hot-spot areas within the Cislunar region and upon the Moon surface, and methods to gather passive information from these regions

The Cislunar region is becoming a focal point of expansion over upcoming decades. Long-term Lunar infrastructure supporting Cislunar expansion must be located in key regions on the Moon\u27s surface and in space. The purpose of this research is to identify key regions of interest on and around the Moon by investigating the location of valuable resources and the destination of future missions. Once key regions are established, low-lunar orbit trajectories are analyzed to enable methods of passive information gain in identified key regions of interest. It has been found that the South Pole and Earth-sided craters are key regions on the Lunar surface in the near future. Furthermore, an analysis of low lunar orbit trajectories is completed and demonstrates a possible framework to service the South Pole region

Feedback Control Methods on Short-Period Orbits Of the Earth-Moon Equilateral Libration Points

Recent research by the authors suggests a unique approach to perform Lunar occultations for a diverse set of scientific applications. Under the circular restricted three-body problem assumptions, short-period orbits (SPOs) near the Earth-Moon equilateral Libration points have been suggested for optimal eclipse time and minimal fuel consumption requirements to stay in orbit. Nevertheless, under the presence of orbital perturbations, SPOs are no longer stable as gravitational effects from neighboring celestial bodies continuously perturb these orbits. In this sense, the current study compares a wide range of control methods, including Lyapunov-based adaptive control schemes and fuel-optimal control policies, to address the fuel consumption and tracking issues of the perturbed system. This inquiry attests that perturbations are effectively cancelled out to achieve the proposed scientific objectives with minimal station-keeping requirements

Development of a "Survival" Guide for Substance Users in Harlem, New York City

Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/40382/2/Factor_Development of a Survival Guide_2002.pd

Development and evaluation of a machine learning-based in-hospital COVID-19 disease outcome predictor (CODOP): A multicontinental retrospective study

New SARS-CoV-2 variants, breakthrough infections, waning immunity, and sub-optimal vaccination rates account for surges of hospitalizations and deaths. There is an urgent need for clinically valuable and generalizable triage tools assisting the allocation of hospital resources, particularly in resource-limited countries. We developed and validate CODOP, a machine learning-based tool for predicting the clinical outcome of hospitalized COVID-19 patients. CODOP was trained, tested and validated with six cohorts encompassing 29223 COVID-19 patients from more than 150 hospitals in Spain, the USA and Latin America during 2020-22. CODOP uses 12 clinical parameters commonly measured at hospital admission for reaching high discriminative ability up to 9 days before clinical resolution (AUROC: 0.90-0.96), it is well calibrated, and it enables an effective dynamic risk stratification during hospitalization. Furthermore, CODOP maintains its predictive ability independently of the virus variant and the vaccination status. To reckon with the fluctuating pressure levels in hospitals during the pandemic, we offer two online CODOP calculators, suited for undertriage or overtriage scenarios, validated with a cohort of patients from 42 hospitals in three Latin American countries (78-100% sensitivity and 89-97% specificity). The performance of CODOP in heterogeneous and geographically disperse patient cohorts and the easiness of use strongly suggest its clinical utility, particularly in resource-limited countries

Reproducibility in the absence of selective reporting : An illustration from large-scale brain asymmetry research

Altres ajuts: Max Planck Society (Germany).The problem of poor reproducibility of scientific findings has received much attention over recent years, in a variety of fields including psychology and neuroscience. The problem has been partly attributed to publication bias and unwanted practices such as p-hacking. Low statistical power in individual studies is also understood to be an important factor. In a recent multisite collaborative study, we mapped brain anatomical left-right asymmetries for regional measures of surface area and cortical thickness, in 99 MRI datasets from around the world, for a total of over 17,000 participants. In the present study, we revisited these hemispheric effects from the perspective of reproducibility. Within each dataset, we considered that an effect had been reproduced when it matched the meta-analytic effect from the 98 other datasets, in terms of effect direction and significance threshold. In this sense, the results within each dataset were viewed as coming from separate studies in an "ideal publishing environment," that is, free from selective reporting and p hacking. We found an average reproducibility rate of 63.2% (SD = 22.9%, min = 22.2%, max = 97.0%). As expected, reproducibility was higher for larger effects and in larger datasets. Reproducibility was not obviously related to the age of participants, scanner field strength, FreeSurfer software version, cortical regional measurement reliability, or regional size. These findings constitute an empirical illustration of reproducibility in the absence of publication bias or p hacking, when assessing realistic biological effects in heterogeneous neuroscience data, and given typically-used sample sizes