No Transits of Proxima Centauri Planets in High-Cadence TESS Data

Proxima Centauri is our nearest stellar neighbor and one of the most well-studied stars in the sky. In 2016, a planetary companion was detected through radial velocity measurements. Proxima Centauri b has a minimum mass of 1.3 Earth masses and orbits with a period of 11.2 days at 0.05 AU from its stellar host, and resides within the star’s Habitable Zone. While recent work has shown that Proxima Centauri b likely does not transit, given the value of potential atmospheric observations via transmission spectroscopy of the closest possible Habitable Zone planet, we reevaluate the possibility that Proxima Centauri b is a transiting exoplanet using data from the Transiting Exoplanet Survey Satellite (TESS). We use three sectors (Sectors 11, 12, and 38 at 2-min cadence) of observations from TESS to search for planets. Proxima Centauri is an extremely active M5.5 star, emitting frequent white-light flares; we employ a novel method that includes modeling the stellar activity in our planet search algorithm. We do not detect any planet signals. We injected synthetic transiting planets into the TESS and use this analysis to show that Proxima Centauri b cannot be a transiting exoplanet with a radius larger than 0.4 R⊕. Moreover, we show that it is unlikely that any Habitable Zone planets larger than Mars transit Proxima Centauri.

Three-Bar structure optimality criterion using the linear resizing rule

The static analysis of the indeterminate three-bar structure is developed using the Castigliano's first theorem, taking the lengths and inclination angles as variables. Some reductions are applied in the resulting set of equations to approximate them to the references models. From now on, the minimum mass optimization model with restrictions is established. Then, the Optimality Criterion linear resizing optimization rule algorithm for the unbounded and bounded design variables is applied in two numerical cases. The analytical and Matlab Optimization Toolbox results are also obtained and they demonstrate the Optimality Criterion linear resizing rule effectiveness in structural optimization with a minimum mass objective and size restrictions.

An enhanced symbiotic organisms search algorithm for design optimization of trusses with frequency constraints

An enhanced symbiotic organisms search (ESOS) algorithm is developed and presented. Modifications to the basic symbiotic organisms search algorithm are carried out in all three phases of the algorithm with the aim of balancing the exploitation and exploration capabilities of the algorithm. To verify validity and capability of the ESOS algorithm in solving general optimization problems, the CEC2014 set of 22 benchmark functions is first optimized and the results are compared with other metaheuristic algorithms. The ESOS algorithm is then used to optimize the sizing and shape of five benchmark trusses with multiple frequency constraints. The best (minimum) mass, mean mass, standard deviation of the mass, total number of function evaluations, and the values of frequency constraints are then compared with those of a number of other metaheuristic solutions available in the literature. It is shown that the proposed ESOS algorithm is generally more efficient in optimizing the shape and sizing of trusses with dynamic frequency constraints compared to other reported metaheuristic algorithms, including the basic symbiotic organisms search and its other recently proposed improved variants such as the improved symbiotic organisms search algorithm (ISOS) and modified symbiotic organisms search algorithm (MSOS).

Optimization of asymmetric I-beams for minimum welding shrinkage

A calculation system has been developed to determine the optimum dimensions of asymmetric I-beams for minimum shrinkage. The objective function is the minimum mass; the unknowns are the I-beam dimensions; the constraints are the stress, local buckling, and deflection. Different steel grades have been considered (235, 355, 460 (MPa) yield stress) and other aluminum alloys (90, 155, 230 (MPa) yield stress). The material, the span length, the loading, and the applied heat input have been changed. It is shown, that using optimum design; the welding shrinkage can be reduced with prebending and can save material cost as well.

The Adult Neck Mass: Predictors of Malignancy

Objective Distinguishing benign from malignant adult neck masses can be challenging because data to guide risk assessment are lacking. We examined patients with neck masses from an integrated health system to identify patient and mass factors associated with malignancy. Study Design Retrospective cohort. Setting Kaiser Permanente Northern California. Methods The medical records of adults referred to otolaryngology in 2017 for a neck mass were evaluated. Bivariate and multivariable logistic regression analyses were performed. Results Malignancy was found in 205 (5.0%) of the cohort’s 4103 patients. Patient factors associated with malignancy included sex, age, and race/ethnicity. Males had more than twice the odds of malignancy compared with females (adjusted odds ratio [aOR] = 2.38). Malignancy rates increased with age, ranging from 2.1% for patients younger than 40 years to 8.4% for patients 70 years or older. White non-Hispanic patients had 1.75 times the risk of malignancy compared with patients of other race/ethnicities. The percentage of patients with malignancy increased with increasing minimum mass dimension, from 3.0% in patients with mass size <1 cm to over 31% in patients with mass sizes 2 cm or larger ( P < .0001). Imaging-based mass factors most highly predictive of malignancy included larger minimum mass dimension (≥1.5 cm vs <1.5 cm: aOR = 3.87), multiple masses (2 or more vs 1: aOR = 5.07), and heterogeneous/ill-defined quality (aOR = 2.57). Conclusion Most neck masses referred to otolaryngology were not malignant. Increasing age, male sex, white non-Hispanic ethnicity, increasing minimum mass dimension, multiple neck masses, or heterogeneous architecture/ill-defined borders were associated with malignancy.

Interior of Jupiter in the context of Juno and Galileo: signature of a decoupling between the atmosphere and the interior

&lt;p&gt;Juno's observations of Jupiter's gravity field have revealed extremely low values for the gravitational moments that are difficult to reconcile with the high abundance of metals observed in the atmosphere by both Galileo and Juno. Recent studies chose to arbitrarily get rid of one of these two constraints in order to build models of Jupiter.&lt;/p&gt;&lt;p&gt;In this presentation, I will detail our new Jupiter structure models reconciling Juno and Galileo observational constraints. These models confirm the need to separate Jupiter into at least 4 layers: an outer convective shell, a non-convective zone of compositional change, an inner convective shell and a diluted core representing about 60 percent of the planet in radius. Compared to other studies, these models propose a new idea with important consequences: a decrease in the quantity of metals between the outer and inner convective shells. This would imply that the atmospheric composition is not representative of the internal composition of the planet, contrary to what is regularly admitted, and would strongly impact the Jupiter formation scenarios (localization, migration, accretion).&lt;/p&gt;&lt;p&gt;In particular, the presence of an internal non-convective zone prevents mixing between the two convective envelopes. I will detail the physical processes of this semi-convective zone (layered convection or H-He immiscibility) and explain how they may persist during the evolution of the planet.&lt;/p&gt;&lt;p&gt;These models also impose a limit mass on the compact core, which cannot be heavier than 5 Earth masses. Such a mass, lower than the runaway gas accretion minimum mass, needs to be explained in the light of our understanding of the formation and evolution of giant planets.&lt;/p&gt;&lt;p&gt;I will finally detail the application of our work to Saturn, and what we can expect to learn about the interior of the giant planets in the years to come.&amp;#160;&lt;/p&gt;