Conventional planet formation theory suggests that chondritic materials have delivered crucial atmospheric and hydrospheric elements such as carbon (C), nitrogen (N), and hydrogen (H) onto primitive ...Earth. However, recent measurements highlight the significant elemental ratio discrepancies between terrestrial parent bodies and the supposed planet building blocks. Here we present a volatile evolution model during the assembly of Earth and Earth-like planets. Our model includes impact losses, atmosphere-mantle exchange, and time dependent effects of accretion and outgassing calculated from dynamical modeling outcomes. Exploring a wide range of planetesimal properties (i.e., size and composition) as well as impact history informed by N-body accretion simulations, we find that while the degree of CNH fractionation has inherent stochasticity, the evolution of C/N and C/H ratios can be traced back to certain properties of the protoplanet and projectiles. Interestingly, the majority of our Earth-like planets acquire superchondritic final C/N ratios, implying that the volatile elemental ratios on terrestrial planets are driven by the complex interplay between delivery, atmospheric ablation, and mantle degassing.
•We linked N-body simulations of planet formation, impact delivery, impact escape, and mantle-atmosphere exchange.•We determine the volatile growth histories in dynamical accretion scenarios.•We constrain the initial composition and size distribution of chondritic materials.•Volatile abundance and ratios can be established by a balance between delivery and loss.•Explanation of measured C/N and C/H on primitive bodies requires a set of complex processes.
VR technology allows learners to access simulated, immersive and interactive virtual environments to perform authentic learning activities. In particular, VR has emerged as a valuable tool for L2 ...learning. However, VR research has tended to pay more attention to desktop-based VR than to VR via mobile-rendered HMDs, leaving the potentials of VR through mobile-rendered HMDs yet to be investigated. Therefore, this study fills the gap by using a commercial VR app to examine the effect of VR via mobile-rendered HMDs on EFL learners' vocabulary learning. Forty-nine seventh graders in Taiwan were recruited from two intact classes and assigned to either an experimental (VR players) or control (video watchers) group. The VR players interacted with Mondly VR app using mobile-rendered HMDs and took part in conversations with virtual characters. The video watchers watched the walkthrough video signal of the VR player's app via a personal computer. Vocabulary tests, a perception questionnaire, and interviews were used to evaluate the participants' vocabulary learning. The results showed that the VR players' vocabulary learning and retention was significantly higher than the video watchers'. The majority of the VR players felt that VR-mediated vocabulary learning was motivating and beneficial. The VR app contextualized vocabulary learning by providing virtual environments with multimodal support and enhanced learner engagement through real-time interactivity and feedback. The video watchers' feedback revealed mixed feelings. Some felt that the walkthrough video facilitated vocabulary learning by providing word meaning and use in context. Others reported it lacked interactivity and their attention was easily distracted.
Willingness to communicate (WTC) is considered to be an important factor contributing to successful foreign language learning. Many studies aim at finding effective tools for enhancing WTC. With the ...support of AI and Automatic Speech Recognition technology, intelligent personal assistants (IPAs) seem to have potentials in improving foreign language learners' WTC. However, few empirical studies focus on the possible impact of IPAs on learners' WTC. This study was conducted to investigate the potentials of an IPA, Google Assistant, for developing adolescent EFL learners' WTC and their perceptions of IPAs for EFL learning. This study recruited 112 eighth-grade EFL learners who engaged in Google-Assistant-language-learning activities for two weeks. Two WTC questionnaires were administered at the beginning and end of the intervention. The results demonstrated that Google Assistant significantly promoted EFL learners' WTC, enhanced communicative confidence, and reduced speaking anxiety. Analyses of interviews revealed that participants enjoyed playing games with Google Assistant and talking to chatbots, which helped them feel less anxious and motivated to use English for real and meaningful communication. The findings indicated that IPA-based interaction provided a less threatening environment, in which learners displayed higher levels of engagement, motivation, confidence, and, in turn, their WTC in the target language.
One of the more rapidly advancing subfields of second language acquisition research is Digital-game based language learning (DGBLL) and many studies have found that Commercial off-the-shelf (COTS) ...games can have a positive effect on vocabulary acquisition. COTS games are specifically made for entertainment purposes, while serious games, which studies have found to enhance language and content knowledge, are designed for educational purposes. In the present study, a serious game titled Slave Trade was adopted to examine whether vocabulary and knowledge of history can be acquired at the same time and to investigate how the participants perceived the serious game regarding language and history learning. Sixty six college EFL students were recruited to take part in this study. They were required to take pre- and post-tests in both vocabulary and content knowledge and to respond to a user survey. The study found statistically significant improvements in both vocabulary and history knowledge. The vocabulary learning can mainly be attributed to the rich contextual clues of the gaming environment and repetitive exposure to the target words (i.e. more than six times). However, it was also found that words of fewer occurrences could be acquired because of the gaming environment. In addition, the students reported that they had enjoyed a positive learning experience via the serious game. Finally, it is suggested that language teachers should consider making educational use of serious games.
Chemotherapy-induced impairment of autophagy is implicated in cardiac toxicity induced by anti-cancer drugs. Imperfect translation from rodent models and lack of in vitro models of toxicity has ...limited investigation of autophagic flux dysregulation, preventing design of novel cardioprotective strategies based on autophagy control. Development of an adult heart tissue culture technique from a translational model will improve investigation of cardiac toxicity. We aimed to optimize a canine cardiac slice culture system for exploration of cancer therapy impact on intact cardiac tissue, creating a translatable model that maintains autophagy in culture and is amenable to autophagy modulation. Canine cardiac tissue slices (350 μm) were generated from left ventricular free wall collected from euthanized client-owned dogs (n = 7) free of cardiovascular disease at the Foster Hospital for Small Animals at Tufts University. Cell viability and apoptosis were quantified with MTT assay and TUNEL staining. Cardiac slices were challenged with doxorubicin and an autophagy activator (rapamycin) or inhibitor (chloroquine). Autophagic flux components (LC3, p62) were quantified by western blot. Cardiac slices retained high cell viability for >7 days in culture and basal levels of autophagic markers remained unchanged. Doxorubicin treatment resulted in perturbation of the autophagic flux and cell death, while rapamycin co-treatment restored normal autophagic flux and maintained cell survival. We developed an adult canine cardiac slice culture system appropriate for studying the effects of autophagic flux that may be applicable to drug toxicity evaluations.
A remarkable discovery of NASA's Kepler mission is the wide diversity in the average densities of planets of similar mass. After gas disk dissipation, fully formed planets could interact with nearby ...planetesimals from a remnant planetesimal disk. These interactions would often lead to planetesimal accretion due to the relatively high ratio between the planet size and the hill radius for typical planets. We present calculations using the open-source stellar evolution toolkit mesa (Modules for Experiments in Stellar Astrophysics) modified to include the deposition of planetesimals into the H/He envelopes of sub-Neptunes (∼1-20 M⊕). We show that planetesimal accretion can alter the mass-radius isochrones for these planets. The same initial planet, as a result of the same total accreted planetesimal mass, can have up to 5% difference in mean densities approximately several gigayears after the last accretion due to the inherent stochasticity of the accretion process. During the phase of rapid accretion, these differences are more dramatic. The additional energy deposition from the accreted planetesimals increase the ratio between the planet's radius to that of the core during rapid accretion, which in turn leads to enhanced loss of atmospheric mass. As a result, the same initial planet can end up with very different envelope mass fractions. These differences manifest as differences in mean densities long after accretion stops. These effects are particularly important for planets that are initially less massive than ∼10 M⊕ and with envelope mass fractions less than ∼10%, thought to be the most common type of planets discovered by Kepler.
Chronological aging as well as biological aging accelerated by various pathologies such as diabetes and obesity contribute to cardiovascular aging, and structural and functional tissue damage of the ...heart and vasculature. Cardiovascular aging in humans is characterized by structural pathologic remodeling including cardiac and vascular fibrosis, hypertrophy, stiffness, micro- and macro-circulatory impairment, left ventricular diastolic dysfunction precipitating heart failure with either reduced or preserved ejection fraction, and cardiovascular cell death. Cellular senescence, an important hallmark of aging, is a critical factor that impairs repair and regeneration of damaged cells in cardiovascular tissues whereas autophagy, an intracellular catabolic process is an essential inherent mechanism that removes senescent cells throughout life time in all tissues. Several recent reviews have highlighted the fact that all longevity treatment paradigms to mitigate progression of aging-related pathologies converge in induction of autophagy, activation of AMP kinase (AMPK) and Sirtuin pathway, and inhibition of mechanistic target of rapamycin (mTOR). These longevity treatments include health style changes such as caloric restriction, and drug treatments using rapamycin, the first FDA-approved longevity drug, as well as other experimental longevity drugs such as metformin, rapamycin, aspirin, and resveratrol. However, in the heart tissue, autophagy induction has to be tightly regulated since evidence show excessive autophagy results in cardiomyopathy and heart failure. Here we discuss emerging evidence for microRNA-mediated tight regulation of autophagy in the heart in response to treatment with rapamycin, and novel approaches to monitor autophagy progression in a temporal manner to diagnose and regulate autophagy induction by longevity treatments.
Abstract
We investigate the evolution of the deuterium-to-hydrogen (D/H) mass ratio driven by EUV photoevaporation of hydrogen-rich atmospheres of close-in sub-Neptunes around solar-type stars. For ...the first time, the diffusion-limited approach in conjunction with energy-limited photoevaporation is considered in evaluating deuterium escape from evolving exoplanet H/He envelopes. We find that the planets with smaller initial gas envelopes and thus smaller sizes can lead to weaker atmospheric escape, which facilitates hydrogen–deuterium fractionation. Specifically, in our grid of simulations with a low envelope mass fraction of less than 0.005, a low-mass sub-Neptune (4–5
M
⊕
) at about 0.25–0.4 au or a high-mass sub-Neptune (10–15
M
⊕
) at about 0.1–0.25 au can increase the D/H values by greater than 20% over 7.5 Gyr. Akin to the helium-enhanced envelopes of sub-Neptunes due to photoevaporating escape, the planets along the upper boundary of the radius valley are the best targets to detect high D/H ratios. The ratio can rise by a factor of ≲1.65 within 7.5 Gyr in our grid of evolutionary calculations. The D/H ratio is expected to be higher in thinner envelopes as long as the planets do not become bare rocky cores.
Intelligent Personal Assistant (IPA) has emerged as a valuable tool for EFL learning by offering interactive authentic contexts. Although IPA is believed to be motivational and useful, empirical ...evidence is limited and contradictory, especially the efficacy of listening comprehension. Therefore, the study investigated the impact of IPA on adolescent EFL learners' listening comprehension, particularly regarding the presentation mode of IPA responses and its interaction styles. Ninety-two ninth-grade EFL learners were recruited from three intact classes and randomly divided into two experimental groups (i.e. GA-Hub group, using Google Nest Hub with multimodal responses; GA-Mini group, using Google Nest Mini with audio responses) and one control group (non-GA group, using a CD player as they did in the conventional class). Both quantitative (English listening tests) and qualitative data (questionnaires and interviews) were collected and analyzed in the 10-week study. The results showed that Google Assistant, especially via Google Nest Hub, positively promoted the participants' listening comprehension. Detailed analyses of interviews demonstrated that Google Assistant provided interactive listening, presented multimodal screen-based responses, encouraged peer collaboration, and offered edutainment (a combination of IPA- and game-based learning), which added authenticity, flexibility, and enjoyment for meaningful interaction and thus promoted EFL listening.
Virtual reality via mobile-rendered head-mounted displays (MVR) has emerged as a valuable language learning tool. However, research has yet to fully access its effects on English as a Foreign ...Language (EFL) listening. Therefore, this study investigated the impact of MVR on EFL learners’ listening comprehension. Seventy-two seventh graders in Taiwan were recruited and randomly assigned to an experimental (MVR player) or control (video watcher) group. The MVR players played the language learning VR app Mondly, using a mobile-rendered head-mounted display. The video watchers watched a walkthrough video of Mondly on a PC screen. Listening comprehension tests, a presence questionnaire and interviews were used to evaluate the participants’ listening comprehension, sense of presence, and perception of MVR-assisted EFL listening. The results showed the MVR players’ listening comprehension and retention was significantly higher than the video watchers’. The interviews revealed that the majority of the MVR players found MVR-assisted EFL listening engaging and beneficial. MVR offered learners access to simulated, interactive, and immersive virtual environments to perform authentic learning activities, helping them activate prior knowledge and make appropriate inferences. Furthermore, virtual presence in MVR brought learner involvement from the fringe to the center, prevented cognitive overload, reduced anxiety, and thus aided comprehension.
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