The effect of temperature evolution on the interior structure of H2{}_{2}O-rich planets

For most planets in the range of radii from 1 to 4 R$_{\oplus}$, water is a major component of the interior composition. At high pressure H${}_{2}$O can be solid, but for larger planets, like Neptune, the temperature can be too high for this. Mass and age play a role in determining the transition between solid and fluid (and mixed) water-rich super-Earth. We use the latest high-pressure and ultra-high-pressure phase diagrams of H${}_{2}$O, and by comparing them with the interior adiabats of various planet models, the temperature evolution of the planet interior is shown, especially for the state of H${}_{2}$O. It turns out that the bulk of H${}_{2}$O in a planet's interior may exist in various states such as plasma, superionic, ionic, Ice VII, Ice X, etc., depending on the size, age and cooling rate of the planet. Different regions of the mass-radius phase space are also identified to correspond to different planet structures. In general, super-Earth-size planets (isolated or without significant parent star irradiation effects) older than about 3 Gyr would be mostly solid.Comment: Accepted by ApJ, in print for March 2014 (14 pages, 3 colored figures, 1 table

cAMP Pulsing of Denuded Mouse Oocytes Increases Meiotic Resumption Via Activation of AMP-activated Protein Kinase

cAMP plays a critical role in the control of oocyte maturation, as a high level of cAMP maintains oocyte arrest at the first meiotic prophase. Yet this study shows that pulsing meiotically arrested denuded oocytes (DO) with cAMP induces oocyte maturation through the activation of AMP-activated protein kinase (PRKA). Short-term (3 h) pulsing of meiotically arrested oocytes with forskolin, an adenyl cyclase (AC) activator, increased oocyte cAMP, led to elevated AMP, and induced oocyte meiotic resumption compared to oocytes continuously cultured in the control medium with or without forskolin. Western analysis showed that germinal vesicle (GV)-stage oocytes after forskolin pulsing contained increased levels of phospho-acetyl CoA carboxylase (pACACA), a primary substrate of PRKA. Pulsing oocytes with the phosphodiesterase (PDE)-sensitive cAMP analog, 8-bromo-cAMP (8-Br-cAMP), also increased pACACA and pPRKA levels in GV-stage oocytes and induced oocyte meiotic resumption. Moreover, the PRKA inhibitors, compound C and araA, prevented 8-Br-cAMP pulsing-induced maturation. The lack of effect on meiotic induction and PRKA activation when oocytes were pulsed with the PDE-resistant activators of cAMP-dependent protein kinase, Sp-cAMP-AM and Sp-5,6-DCI-cBIMPS, suggests that cAMP degradation is required for pulsing-induced maturation. Pulsing oocytes with the exchange protein directly activated by cAMP (Epac)-specific activator, 8-CPT-2′-O-Me-cAMP, had no stimulatory effect on oocyte maturation, suggesting Epac is not involved in the pulsing-induced maturation. Taken together, these data support the idea that a transient increase in oocyte cAMP can induce meiotic resumption via activation of PRKA

In-process monitoring and analysis of bearing outer race way grinding based on the power signal

In production engineering, monitoring of the grinding process is critical for acquiring information on material removal, wheel performance, and workpiece quality. Here, a general model of the power signal and material removal rate is proposed to monitor the internal plunge grinding of a bearing outer race way product. Three continuous grinding cycles after dressing were used to analyse the roughing, semi-finishing, finishing and spark-out process under the same parameters. Based on the actual grinding process, a practical analysis method is applied to improve the general model to predict more accurately the power curve. Finally, estimations of grinding wheel performance and grind quality using the grinding power signal model (GPSM) coefficients are also presented. The experimental results showed that the improved power signal model is capable of solving the industrial problem of multi-stage in-feed grinding cycles and improving grind quality

First-principles method of propagation of tightly bound excitons: exciton band structure of LiF and verification with inelastic x-ray scattering

We propose a simple first-principles method to describe propagation of tightly bound excitons. By viewing the exciton as a composite object (an effective Frenkel exciton in Wannier orbitals), we define an exciton kinetic kernel to encapsulate the exciton propagation and decay for all binding energy. Applied to prototypical LiF, our approach produces three exciton bands, which we verified quantitatively via inelastic x-ray scattering. The proposed real-space picture is computationally inexpensive and thus enables study of the full exciton dynamics, even in the presence of surfaces and impurity scattering. It also provides intuitive understanding to facilitate practical exciton engineering in semiconductors, strongly correlated oxides, and their nanostructures.Comment: 5 pages, 4 figures. Accepted by PR

Hierarchical Reinforcement Learning for Modeling User Novelty-Seeking Intent in Recommender Systems

Recommending novel content, which expands user horizons by introducing them to new interests, has been shown to improve users' long-term experience on recommendation platforms \cite{chen2021values}. Users however are not constantly looking to explore novel content. It is therefore crucial to understand their novelty-seeking intent and adjust the recommendation policy accordingly. Most existing literature models a user's propensity to choose novel content or to prefer a more diverse set of recommendations at individual interactions. Hierarchical structure, on the other hand, exists in a user's novelty-seeking intent, which is manifested as a static and intrinsic user preference for seeking novelty along with a dynamic session-based propensity. To this end, we propose a novel hierarchical reinforcement learning-based method to model the hierarchical user novelty-seeking intent, and to adapt the recommendation policy accordingly based on the extracted user novelty-seeking propensity. We further incorporate diversity and novelty-related measurement in the reward function of the hierarchical RL (HRL) agent to encourage user exploration \cite{chen2021values}. We demonstrate the benefits of explicitly modeling hierarchical user novelty-seeking intent in recommendations through extensive experiments on simulated and real-world datasets. In particular, we demonstrate that the effectiveness of our proposed hierarchical RL-based method lies in its ability to capture such hierarchically-structured intent. As a result, the proposed HRL model achieves superior performance on several public datasets, compared with state-of-art baselines

Prompt Tuning Large Language Models on Personalized Aspect Extraction for Recommendations

Existing aspect extraction methods mostly rely on explicit or ground truth aspect information, or using data mining or machine learning approaches to extract aspects from implicit user feedback such as user reviews. It however remains under-explored how the extracted aspects can help generate more meaningful recommendations to the users. Meanwhile, existing research on aspect-based recommendations often relies on separate aspect extraction models or assumes the aspects are given, without accounting for the fact the optimal set of aspects could be dependent on the recommendation task at hand. In this work, we propose to combine aspect extraction together with aspect-based recommendations in an end-to-end manner, achieving the two goals together in a single framework. For the aspect extraction component, we leverage the recent advances in large language models and design a new prompt learning mechanism to generate aspects for the end recommendation task. For the aspect-based recommendation component, the extracted aspects are concatenated with the usual user and item features used by the recommendation model. The recommendation task mediates the learning of the user embeddings and item embeddings, which are used as soft prompts to generate aspects. Therefore, the extracted aspects are personalized and contextualized by the recommendation task. We showcase the effectiveness of our proposed method through extensive experiments on three industrial datasets, where our proposed framework significantly outperforms state-of-the-art baselines in both the personalized aspect extraction and aspect-based recommendation tasks. In particular, we demonstrate that it is necessary and beneficial to combine the learning of aspect extraction and aspect-based recommendation together. We also conduct extensive ablation studies to understand the contribution of each design component in our framework

AMPK Regulation of Mouse Oocyte Meiotic Resumption in Vitro

We have previously shown that the adenosine analog 5-aminoimidazole-4-carboxamide-1-β-d-ribofuranoside (AICAR), an activator of AMP-activated protein kinase (AMPK), stimulates an increase in AMPK activity and induces meiotic resumption in mouse oocytes [Downs, S.M., Hudson, E.R., Hardie, D.G., 2002. A potential role for AMP-activated protein kinase in meiotic induction in mouse oocytes. Dev. Biol, 245, 200–212]. The present study was carried out to better define a causative role for AMPK in oocyte meiotic maturation. When microinjected with a constitutively active AMPK, about 20% of mouse oocytes maintained in meiotic arrest with dibutyryl cAMP (dbcAMP) were stimulated to undergo germinal vesicle breakdown (GVB), while there was no effect of catalytically dead kinase. Western blot analysis revealed that germinal vesicle (GV)-stage oocytes cultured in dbcAMP-containing medium plus AICAR possessed elevated levels of active AMPK, and this was confirmed by AMPK assays using a peptide substrate of AMPK to directly measure AMPK activity. AICAR-induced meiotic resumption and AMPK activation were blocked by compound C or adenine 9-beta-d-arabinofuranoside (araA, a precursor of araATP), both inhibitors of AMPK. Compound C failed to suppress adenosine uptake and phosphorylation, indicating that it did not block AICAR action by preventing its metabolism to the AMP analog, ZMP. 2′-Deoxycoformycin (DCF), a potent adenosine deaminase inhibitor, reversed the inhibitory effect of adenosine on oocyte maturation by modulating intracellular AMP levels and activating AMPK. Rosiglitazone, an anti-diabetic agent, stimulated AMPK activation in oocytes and triggered meiotic resumption. In spontaneously maturing oocytes, GVB was preceded by AMPK activation and blocked by compound C. Collectively, these results support the proposition that active AMPK within mouse oocytes provides a potent meiosis-inducing signal in vitro