The dominant features of the internet linguistics

This research aims at the modern Internet linguistics features by carrying out linguistic analysis using descriptive statistics of students in distance learning. A linguistic analysis found that most students used lexical, orthographic, paralinguistic, and graphic features when communicating in an online classroom. A total of 452 messages, containing a corpus of 6,340 words, were analyzed and found that only 23.72% of the total corpus was found with lexical, spelling, paralinguistic and graphical features at the Massachusetts Institute of Technology, 22.63% at Stanford University, 21.78% at Harvard University, 24.58% at the California Institute of Technology and 22.76% at Oxford University.

FIRST FINDINGS ON COMETARY ACTIVITY FROM THE PTF COMET SAMPLE

We present preliminary results from the Palomar Transient Factory (PTF) uniform sample of short period comets (SPCs) and long period comets (LPCs), captured between September 2009 and March 2013. We study their dynamical and physical properties in relation to their activity for a better understanding of cometary evolution. This observing campaign was part of PTF in its intermediate phase (iPTF) at the California Institute of Technology (Caltech). The photometric sample comprises more than 180 comets, which makes it one of the largest samples studied to-date. We present a new approach to identifying active comets that compares subtracted aperture magnitudes of comets with the distribution of stars of similar brightness in each image. In this paper, we present initial findings on cometary activity in relationship to their perihelion distances. We show differences between the distributions of the SPCs and that of the LPCs. As others predicted, it seems that a larger fraction of LPCs are found to be active at larger perihelia than for the SPCs. We look at ratios of active comets in different perihelia brackets and compare those to previous works and results. We do not discuss the statistical significance of our findings as this is still work in progress.

Realizing the Potential of JWST High Contrast Imaging with Coronagraphic Phase-Retrieval

<div>  The James Webb Space Telescope (JWST) will probe circumstellar environments at an unprecedented sensitivity. However, the performance of high-contrast imaging instruments is limited by the residual light from the star at close separations (<2-3”), where the incidence of exoplanets increases rapidly. There is currently no solution to get rid of the residual light down to the photon noise level at those separations, which may prevent some crucial discoveries.</div> <div>  We are further developing and implementing a potentially game-changing technique of post-processing that does not require the systematic observation of a reference star, but instead directly uses data from the science target by taking advantage of the technique called “phase retrieval”. This technique is built on a Bayesian framework that provides a more robust determination of faint astrophysical structures around a bright source.</div> <div>  This approach uses a model of instrument that takes advantage of prior information, such as data from wavefront sensing operations on JWST, to estimate instrumental aberrations and further push the limits of high-contrast imaging. With this approach, our goal is to improve the contrast that can be achieved with JWST instruments.</div> <div>  We were awarded a JWST GO-Calibration proposal to implement, test and validate this approach on NIRCam imaging and coronagraphic imaging. This work will pave the way for the future space-based high-contrast imaging instruments such as the Nancy Grace Roman Space Telescope Coronagraph Instrument (Roman CGI). This technique will be crucial to make the best use of the telemetry data that will be collected during the CGI operations.</div> <div>  <br />“© 2021 California Institute of Technology. Government sponsorship acknowledged. The research was carried out in part at the Jet Propulsion Laboratory, California Institute of Technology, under a contract with the National Aeronautics and Space Administration. This document has been reviewed and determined not to contain export controlled data.”</div>

Compositional mapping of Titan’s surface using Cassini VIMS and RADAR data

<p>The investigation of Titan’s surface chemical composition is of great importance for the understanding of the atmosphere-surface-interior system of the moon. The Cassini cameras and especially the Visual and infrared Mapping Spectrometer has provided a sequence of spectra showing the diversity of Titan’s surface spectrum from flybys performed during the 13 years of Cassini’s operation. In the 0.8-5.2 μm range, this spectro-imaging data showed that the surface consists of a multivariable geological terrain hosting complex geological processes. The data from the seven narrow methane spectral “windows” centered at 0.93, 1.08, 1.27, 1.59, 2.03, 2.8 and 5 μm provide some information on the lower atmospheric context and the surface parameters. Nevertheless, atmospheric scattering and absorption need to be clearly evaluated before we can extract the surface properties. In various studies (Solomonidou et al., 2014; 2016; 2018; 2019; 2020a, 2020b; Lopes et al., 2016; Malaska et al., 2016; 2020), we used radiative transfer modeling in order to evaluate the atmospheric scattering and absorption and securely extract the surface albedo of multiple Titan areas including the major geomorphological units. We also investigated the morphological and microwave characteristics of these features using Cassini RADAR data in their SAR and radiometry mode. Here, we present a global map for Titan’s surface showing the chemical composition constraints for the various units. The results show that Titan’s surface composition, at the depths detected by VIMS, has significant latitudinal dependence, with its equator being dominated by organic materials from the atmosphere and a very dark unknown material, while higher latitudes contain more water ice. The albedo differences and similarities among the various geomorphological units give insights on the geological processes affecting Titan’s surface and, by implication, its interior. We discuss our results in terms of origin and evolution theories.</p> <p>References: [1] Solomonidou, A., et al. (2014), J. Geophys. Res. Planets, 119, 1729; [2] Solomonidou, A., et al. (2016), Icarus, 270, 85; [3] Solomonidou, A., et al. (2018), J. Geophys. Res. Planets, 123, 489; [4] Solomonidou, A., et al. (2020a), Icarus, 344, 113338; [5] Solomonidou, A., et al. (2020b), A&A 641, A16; [6] Lopes, R., et al. (2016) Icarus, 270, 162; [7] Malaska, M., et al. (2016), Icarus 270, 130; [8] Malaska, M., et al. (2020), Icarus, 344, 113764.</p> <p>Acknowledgements: This work was conducted at the California Institute of Technology (Caltech) under contract with NASA. Y.M. and A.S. (partly) was  supported by the Czech Science Foundation (grant no. 20-27624Y). ©2021 California Institute of Technology. Government sponsorship acknowledged.</p>

НАУКОВЕ ЗАБЕЗПЕЧЕННЯ ПРОЄКТУ «ПРЕЗИДЕНТСЬКИЙ УНІВЕРСИТЕТ»

Представлено візію, місію, ключові особливості Президентського університету, діяльність якого спрямовуватиметься на впровадження ефективних освітніх стратегій для реалізації інтелектуального і творчого потенціалу громадян України, що забезпечить підготовку лідерів для стратегічних галузей розвитку держави, готових до викликів сучасного мінливого світу. Наведено стратегічні цілі для реалізації діяльності університету як сучасного інноваційного освітнього і наукового центру. Висвітлено порівняльні концептуальні характеристики Каліфорнійського інституту технології (California Institute of Technology, Caltech) та майбутнього Президентського університету. Наведено ризики, зумовлені відсутністю законодавчого забезпечення, особливим статусом університету, складністю конкурентних умов з топовими українськими університетами.

Smart Power Supply Calibration System

This paper details the development of an automated procedure to conduct calibrations of power supplies at Jet Propulsion Laboratory, California Institute of Technology (JPL). The fundamentals of power supply calibrations are given, and discussion on the method by which this custom software handles that calibration. Additionally, this technique provides real time uncertainty quantification of the calibrations. This automated system has demonstrated a time savings over existing automated techniques in use today.

“…this Brazilian venture…” A brief biography of Theodosius Dobzhansky before he arrived in Brazil

This paper describes life and career of Theodosius Dobzhansky (1900-1975) until he arrived in Brazil in 1943. During his years in Russia, Dobzhansky began his entomology studies and undertook research expeditions to Central Asia to study livestock, which focused on speciation biology. Once he arrived in the United States Dobzhansky began working with Drosophila melanogaster with Thomas Hunt Morgan (1866-1945) at Columbia University. Once Morgan relocated to the California Institute of Technology (Caltech), Dobzhansky started collaborating with his colleague, Alfred Henry Sturtevant (1891-1970), on studies of a wild cousin of Drosophila melanogaster, Drosophila pseudoobscura. Dobzhansky and Sturtevant’s friendship and collaboration suffered due to several factors, including most importantly, their differing approaches to Drosophila pseudoobscura as influenced by their different conceptions of the purpose of their work. While Sturtevant studied the flies using the same techniques as his studies of the domestic Drosophila melanogaster, Dobzhansky studied Drosophila pseudoobscura in the field considering his broader dictum that “Nothing in biology makes sense except in the light of evolution.”

A baseline Antarctic GIA correction for space gravimetry

<p class="western"><span>Within the past decade, newly collected GPS data and geochronological constraints have resulted in refinement of glacial isostatic adjustment (GIA) models for Antarctica. These are critical to understanding ice mass changes at present-day. A correction needs to be made when using space gravity for ice mass balance assessments as any vertical movements of the solid Earth masquerade as changes in ice mass, and must be carefully removed. The main upshot of the new Antarctic GIA models is a downward revision of negative ice mass trends deduced from the Gravity Recovery and Climate Experiment (GRACE), resulting from a reduced GIA correction. This revision places GRACE inferred trend in mass balance within the 1-σ uncertainty of mass balance deduced by altimetry. Because uncertainties in Holocene ice history and the low viscosity rheology beneath the West Antarctic Ice Sheet (WAIS) continue to vex further improvement in predictions of present-day GIA gravity rate, more emphasis has been given to regional-scale GIA models. Here we use a Bayesian method to explore the gravimetric GIA trend over Antarctica, both with and without the impact of a late Pleistocene Antarctic ice loads, along with the contribution of oceanic loads. We call this model without loads associated with Antarctica a baseline for regional GIA models to build upon. We consider variations of the radial mantle viscosity profile and the volume of continental-scale ice sheets during the last glacial cycle. The modeled baseline GIA is mainly controlled by the lower mantle viscosity and continental levering caused by ocean loading. We find that the predicted baseline GIA correction weakly depends on the ice history. This correction averages to +28.4 [16.5–41.9, 95% confidence] Gt/yr. In contrast, with Pleistocene Antarctic-proximal ice included, the total modeled mass trend due to GIA is +73.7 [30.1–114.7] Gt/yr. A baseline GIA correction of 28.4 Gt/yr is of order 50% of the mean net mass trend measured during the period 1992-2017. The statistical analysis provides tools for synthesizing any regional Antarctic GIA model with a self-consistent far-field component. This may prove important for accounting for both global and regional 3-D variations in mantle viscosity.</span></p> <p class="western"><span>© 2020 California Institute of Technology.<br />Government sponsorship acknowledged. This work was performed at the California Institute of Technology's Jet Propulsion Laboratory under a contract with the National Aeronautics and Space Administration's Cryosphere Science Program. </span></p>

A Selective History of the Jet Propulsion Laboratory

The Jet Propulsion Laboratory (JPL) of the California Institute of Technology had its origins in a student project to develop rocket propulsion in the late 1930s. It attracted funding from the U.S. Army just prior to U.S. entry into World War II and became an Army missile research facility in 1943. Because of its origins as a contractor-operated Army research facility, JPL is the National Aeronautics and Space Administration’s (NASA) only contractor-operated field center. It remains a unit of the California Institute of Technology. In the decades since its founding, the laboratory, first under U.S. Army direction and then as a NASA field center, has grown and evolved into an internationally recognized institution generally seen as a leader in solar system exploration but whose portfolio includes substantial Earth remote sensing. JPL’s history includes episodes where the course of the laboratory’s development took turning points into new directions. After developing short-range ballistic missiles for the Army, the laboratory embarked on a new career in lunar and planetary exploration through the early 1970s and abandoned its original purpose as a propulsion technology laboratory. It developed the telecommunications infrastructure for planetary exploration too. It diversified into Earth science and astrophysics in the late 1970s and, due to a downturn in funding for planetary exploration, returned to significant amounts of defense work in the 1980s. The end of the Cold War between 1989 and 1991 resulted in a declining NASA budget, but support for planetary exploration actually improved within NASA management—as long as that exploration could be done more cheaply. This resulted in what is known as the “Faster Better Cheaper” period in NASA history. For JPL, this ended in 2000, succeeded by a return to more rigorous technical standards and increased costs.