The Spin-Orbit Evolution of GJ 667C System: The Effect of Composition and Other Planet's Perturbations

Potentially habitable planets within the habitable zone of M-dwarfs are affected by tidal interaction. We studied the tidal evolution in GJ 667C using a numerical code we call TIDEV. We reviewed the problem of the dynamical evolution focusing on the effects that a rheological treatment, different compositions and the inclusion of orbital perturbations, have on the spin-down time and the probability to be trapped in a low spin-orbit resonance. Composition have a strong effect on the spin-down time, changing, in some cases, by almost a factor of 2 with respect to the value estimated for a reference Earth-like model. We calculated the time to reach a low resonance value (3:2) for the configuration of 6 planets. Capture probabilities are affected when assuming different compositions and eccentricities variations. We chose planets b and c to evaluate the probabilities of capture in resonances below 5:2 for two compositions: Earth-like and Waterworld planets. We found that perturbations, although having a secular effect on eccentricities, have a low impact on capture probabilities and noth- ing on spin-down times. The implications of the eccentricity variations and actual habitability of the GJ 667C system are discussed.Comment: 15 pages, 9 figures, 4 tables. Accepted for publication in MNRAS - V

El concepto de proporcionalidad en el contexto del modelo de van Hiele

El presente trabajo de investigación aborda los razonamientos que tienen los estudiantes del grado quinto sobre el concepto de proporcionalidad, según el modelo educativo de van Hiele; por lo tanto, el estudio permitió establecer unos descriptores de nivel que caracterizaron y determinaron el nivel de razonamiento en que se encontraban razonando dichos estudiantes. Este estudio se desarrolló en el marco del programa de Maestría en Educación, en la línea de educación matemática, que se desarrolla en una de las sedes regionales de la Universidad de Antioquia, con la participación del grupo de investigación EDUMATH

The Spin-Orbit Evolution of GJ 667C System: The Effect of Composition and Other Planet’s Perturbations

Potentially habitable planets within the habitable zone of M dwarfs are affected by tidal interaction. We studied tidal evolution in GJ 667C using a numerical code we call TIDEV. We reviewed the problem of dynamical evolution, focusing on the effects of a rheological treatment, different compositions and the inclusion of orbital perturbations on the spin-down time and the probability of becoming trapped in a low spin-orbit resonance. The composition has a noticeable effect on the spin-down time, which changes, in some cases, by almost a factor of 2 with respect to the value estimated for a reference Earth-like model. We calculated the time required to reach a low resonance value (3:2) for a configuration of six planets. Capture probabilities are affected when assuming different compositions and eccentricity variations. We chose planets b and c to evaluate the probabilities of capture in resonances below 5:2 for two compositions: Earth-like and Waterworld planets. We found that perturbations, although having a secular effect on eccentricities, have a low impact on capture probabilities and no effect on spin-down times. The implications of the eccentricity variations and actual habitability of the GJ 667C system are discussed.Facultad de Ciencias Astronómicas y Geofísica

Updating dynamic noise models with moving magnetoencephalographic (MEG) systems

Optically pumped magnetometers have opened many possibilities for the study of human brain function using wearable moveable technology. In order to fully exploit this capability, a stable low-field environment at the sensors is required. One way to achieve this is to predict (and compensate for) changes in the ambient magnetic field as the subject moves through the room. The ultimate aim is to account for dynamically changing noise environments by updating a model based on measurements from a moving sensor array. We begin by demonstrating how an appropriate environmental spatial noise model can be developed through Free-energy based model selection. We then develop a Kalman-filter based strategy to account for dynamically changing interference. We demonstrate how such a method could not only provide realistic estimates of interfering signals when the sensors are moving, but also provide powerful predictive performance (at a fixed point within the room) when both sensors and sources of interference are in motion

A Quantitative 3D Motility Analysis of Trypanosoma brucei by Use of Digital In-line Holographic Microscopy

We present a quantitative 3D analysis of the motility of the blood parasite Trypanosoma brucei. Digital in-line holographic microscopy has been used to track single cells with high temporal and spatial accuracy to obtain quantitative data on their behavior. Comparing bloodstream form and insect form trypanosomes as well as mutant and wildtype cells under varying external conditions we were able to derive a general two-state-run-and-tumble-model for trypanosome motility. Differences in the motility of distinct strains indicate that adaption of the trypanosomes to their natural environments involves a change in their mode of swimming

Deciphering pyritization-kerogenization gradient for fish soft-tissue preservation.

Soft-tissue preservation provides palaeobiological information that is otherwise lost during fossilization. In Brazil, the Early Cretaceous Santana Formation contains fish with integument, muscles, connective tissues, and eyes that are still preserved. Our study revealed that soft-tissues were pyritized or kerogenized in different microfacies, which yielded distinct preservation fidelities. Indeed, new data provided the first record of pyritized vertebrate muscles and eyes. We propose that the different taphonomic pathways were controlled by distinct sedimentation rates in two different microfacies. Through this process, carcasses deposited in each of these microfacies underwent different residence times in sulphate-reduction and methanogenesis zones, thus yielding pyritized or kerogenized softtissues, and a similar process has previously been suggested in studies of a late Ediacaran lagerst?tte

Constraints for exomoon detectability via tidal migration

Detection of exoplanets has been a fruitful task over the last decades only tarnished by the lack of confirmed exomoons. The observational bias related to the current methods of detecting exoplanets, as well as the strong dynamical effects that an exomoon of a close-in giant exoplanet undergoes, may be the cause of this absence of positive results. For these kind of systems, and according to newly models for tidal migration of exomoons that consider the evolution of planetary parameters such as its size, Love's number and tidal quality factor, the torque's interplay triggers the orbital evolution of the satellite until its semimajor-axis reaches a stationary value, nicknamed in advance as the \textit{tidal migration's braking point} (TMBP) of the system. The TMBP value mainly depends on a set of initial parameters as the moon and planet masses, distances and rotational rates. On the other hand, the detection of an exomoon is directly related to the moon's size, mass and moon-planet separation, which might be constrained by the satellital tidal biography. In this work we explored the set of initial orbital and physical parameter for a planet-moon system, to numerically asses the TMBP in order to obtain some constraints for exomoon detectability by diverse methods of namely, transits, radial velocity, TTV and TDV, with the instrumentation currently available

Revisiting the sample transmittance and camera bit-depth effects on quantitative phase imaging in off-axis digital holographic microscopy

[EN] The performance of single -shot off -axis digital holographic microscopy (DHM) is determined by the optimum utilization of the space -bandwidth product and by the contrast of the recorded digital hologram. While the former can be easily achieved through an afocal-telecentric DHM, the finding in nature of samples with nonhomogeneous transmittance leads to the recording of digital holograms with contrast ranging from zero to unity. In this work, the effect of the sample transmittance and the bit depth of the digital camera on the performance of quantitative phase imaging in DHM is studied. A theoretical model that links the contrast of the recorded interference fringes, in a transmission -mode DHM, to the bit depth of the digital camera is derived. The model is implemented in an open -source visual script for easy consultation and predicts that, when recorded with a 16 -bit -depth camera, digital holograms of samples that have regions with transmittance below 1% can be successfully processed to render reliable phase information. The theoretical and computer -modeled results are validated with experimental results from a complex sample of the mouth of a honeybee and from endothelial cells slide.This work was funded in part by Generalitat Valenciana, Spain, through project CIPROM/2022/30. C. Buitrago-Duque thanks the Universitat de Valencia for its support through the "Beca Jovenes Investigadores 2022". J. Garcia-Sucerquia thanks Fundacion Carolina and Universidad Nacional de Colombia for their support in finishing this work.Buitrago-Duque, C.; Garcia-Sucerquia, J.; Martínez-Corral, M.; Sánchez-Ortiga, E. (2024). Revisiting the sample transmittance and camera bit-depth effects on quantitative phase imaging in off-axis digital holographic microscopy. Optics and Lasers in Engineering. 175. https://doi.org/10.1016/j.optlaseng.2023.10800217

Speckle reduction of reconstructions of digital holograms using three dimensional filtering

Maycock J, McDonald JB, Hennelly BM. Speckle reduction of reconstructions of digital holograms using three dimensional filtering. Optics Communications. 2013;300:142-155