Seismic structure of the mantle beneath the southwestern Pacific

Thesis (S.M.)--Massachusetts Institute of Technology, Dept. of Earth, Atmospheric, and Planetary Sciences, 2001.Includes bibliographical references (leaves 24-28).We jointly invert 1396 frequency-dependent travel times of turning and surface waves such as S, sS, SS, sSS, SSS, Sa, R1, and G1, together with 82 travel times of multiple ScS waves, to obtain a high-resolution, two-dimensional (2-D) vertical tomogram for the corridor between the Ryukyu subduction zone and Hawaii, which traverses the Hawaiian Swell between Midway and Oahu. The data analysis, inversion procedure, and parameterization are similar to our previous study along the Tonga-Hawaii corridor [Katzman et al., 1998], but in this study we add corrections to the measurements that account for the crustal heterogeneity and topography along the path. The model parameters include shear-speed variations throughout the mantle, perturbations to shearwave radial anisotropy in the uppermost mantle, and the topographies of the 410- and 660-km discontinuities. The model we obtained, which is well resolved in the upper mantle, exhibits high shear speeds at shallow depths and low speeds in the transition zone beneath the Pacific part of the corridor, with the lowest shear speed within a distinct upper-mantle anomaly at the depth of 200-400km near the Hawaiian Swell. Furthermore, we inverted the data from individual source arrays in New Hebrides, Solomon, and Mariana Island for two-dimensional vertical tomograms of mantle structure using the same technique as the Ryukyu-Hawaii corridor. The 2-D tomograms for these corridors were generally consistent with previous tomographic results, although they show uppermantle features that are smaller in scale and larger amplitude than published global models. We then inverted the entire data set from all corridors for a 3-D model of the southwestern Pacific upper mantle. At low wavenumbers, this regional model is consistent with large-scale features found from global tomography. However, our model displays greater lateral heterogeneity in both isotropic and anisotropic structure than the global models, especially in the 200-400 km depth range, which can be attributed to the better resolution of small-scale features by our data set. Fast and slow anomalies in isotropic shear speed are observed in the upper mantle, suggesting a complex 3-D mantle flow in the southwestern Pacific upper mantle.by Liangjun Chen.S.M

Inference on many jumps in nonparametric panel regression models

We investigate the significance of change-points within fully nonparametric regression contexts, with a particular focus on panel data where data generation processes vary across units, and error terms may display complex dependency structures. In our setting the threshold effect depends on one specific covariate, and we permit the true nonparametric regression to vary based on additional (latent) variables. We propose two uniform testing procedures: one to assess the existence of change-points and another to evaluate the uniformity of such effects across units. Our approach involves deriving a straightforward analytical expression to approximate the variance-covariance structure of change-point effects under general dependency conditions. Notably, when Gaussian approximations are made to these test statistics, the intricate dependency structures within the data can be safely disregarded owing to the localized nature of the statistics. This finding bears significant implications for obtaining critical values. Through extensive simulations, we demonstrate that our tests exhibit excellent control over size and reasonable power performance in finite samples, irrespective of strong cross-sectional and weak serial dependency within the data. Furthermore, applying our tests to two datasets reveals the existence of significant nonsmooth effects in both cases

Increased FTO Expression Demethylates XBP1 m6A, Thereby Regulating XBP1-C/EBPα and Promoting Hepatocellular Carcinoma Growth

Background: N6-methyladenosine (m6A) modification predominantly occurs in cancer cells mRNA. The X-box binding protein 1 (XBP1) influences hepatocellular carcinoma (HCC) progression, but its m6A regulatory mechanism remains unclear. Furthermore, the dysregulation of CCAAT/enhancer binding proteins alpha (C/EBPα) in liver cancer is influenced by fat mass and obesity-associated protein (FTO) and acts downstream of XBP1. Therefore, this study aims to investigate how FTO catalyzes XBP1 m6A demethylation in HCC regulation. Methods: Initially, HepG2 cells were used to construct FTO overexpression and knockdown cells. The cells were divided into the FTO overexpression group (oe-FTO), overexpression control group (oe-NC), FTO knocked-down group (sh-FTO), and control of FTO knocked-down group (sh-NC) groups. RNA immunoprecipitation quantitative polymerase chain reaction (RIP-qPCR) was used to determine the interaction between FTO and XBP1. Furthermore, quantitative real time polymerase chain reaction (qRT-PCR) and Western blotting (WB) analysis were utilized to assess the expression levels of XBP1 and C/EBPα. Additionally, subcutaneous transplanted tumor models were constructed and the tumor size, weight, and occurrence time were monitored. Moreover, Hematoxylin-Eosin (H&E) staining was employed to observe the pathological changes of tumors. m6A immunoprecipitation (MeRIP)-qPCR was used to evaluate the XBP1 m6A modification levels. qRT-PCR and WB analysis were used to determine the expression levels of XBP1 and C/EBPα. Results: We observed that FTO specifically binds to XBP1 mRNA in HCC cells, indicating a potential regulatory role at the RNA level. At the cellular level, compared to the sh-NC and oe-NC groups, the m6A methylation level of XBP1 was significantly increased in the sh-FTO group, while it was decreased in the oe-FTO group (p < 0.05). Furthermore, the mRNA and protein expression levels of FTO, XBP1, and C/EBPα were altered following FTO manipulation. Functional assays demonstrated that FTO overexpression promoted cell proliferation and invasion while inhibiting apoptosis. Conversely, FTO knockdown resulted in decreased cell proliferation and invasion and increased apoptosis. In a mouse xenograft tumor model, we observed rapidly growing tumors in the oe-FTO group, whereas sh-FTO tumors exhibited slower growth. Histological analysis revealed distinct patterns of tumor growth and damage. Collectively, these findings suggest that FTO plays a crucial role in HCC progression through its effects on XBP1 and C/EBPα, providing insights into the potential therapeutic intervention of FTO in hepatocellular carcinoma. Conclusion: FTO overexpression leads to m6A demethylation of XBP1, thereby modulating the expression of XBP1-C/EBPα and suppressing cell apoptosis. This, in turn, facilitates the progression of hepatocellular carcinoma by promoting cell growth

Automatic Robotic Development through Collaborative Framework by Large Language Models

Despite the remarkable code generation abilities of large language models LLMs, they still face challenges in complex task handling. Robot development, a highly intricate field, inherently demands human involvement in task allocation and collaborative teamwork . To enhance robot development, we propose an innovative automated collaboration framework inspired by real-world robot developers. This framework employs multiple LLMs in distinct roles analysts, programmers, and testers. Analysts delve deep into user requirements, enabling programmers to produce precise code, while testers fine-tune the parameters based on user feedback for practical robot application. Each LLM tackles diverse, critical tasks within the development process. Clear collaboration rules emulate real world teamwork among LLMs. Analysts, programmers, and testers form a cohesive team overseeing strategy, code, and parameter adjustments . Through this framework, we achieve complex robot development without requiring specialized knowledge, relying solely on non experts participation

Testing Homogeneity in Panel Data Models with Interactive Fixed Effects

This paper proposes a residual-based Lagrange Multiplier (LM) test for slope homogeneity in large-dimensional panel data models with interactive fixed effects. We first run the panel regression under the null to obtain the restricted residuals and then use them to construct our LM test statistic. We show that after being appropriately centered and scaled, our test statistic is asymptotically normally distributed under the null and a sequence of Pitman local alternatives. The asymptotic distributional theories are established under fairly general conditions that allow for both lagged dependent variables and conditional heteroskedasticity of unknown form by relying on the concept of conditional strong mixing. To improve the finite-sample performance of the test, we also propose a bootstrap procedure to obtain the bootstrap p-values and justify its validity. Monte Carlo simulations suggest that the test has correct size and satisfactory power. We apply our test to study the Organization for Economic Cooperation and Development economic growth model.</jats:p

The Development of NBA in China: A Glocalization Perspective

The growing sport industry and 1.3 billion potential consumers in China have been garnering tremendous attention from more and more overseas professional sport leagues. Comparatively, the National Basketball Association (NBA) has had remarkable success in the Chinese market. From the perspective of sport competition or marketing operations, the NBA’s achievement in China provides a model for other overseas sport leagues. This case study was organized by summarizing the developmental history of NBA in China, analyzing its current promotional practices, investigating into its marketing strategies, and extrapolating practical references for other sport leagues aiming to penetrating into the Chinese marketplace. In the perspective of glocalization, multinational corporations should combine both standardized and adapted elements to conceptualize globally and act locally (Tanahashi, 2008). By taking this approach, marketers can meet the needs of local consumers effectively while still maintaining some extent of global standardization (Singh, Kumar, & Baack, 2005). To obtain in-depth understanding about NBA globalization and localization in China, we conducted one-on-one interviews with Chinese academic scholars in sport management and practitioners in Chinese basketball industry and NBA China. Two focus groups with six participants in each group were conducted to learn the perception of NBA products from the perspective of Chinese consumer. The qualitative data analysis was organized around four major aspects: products, media, management and public relations, which were highlighted in the glocalization of transnational corporations (Yang, 2003; Zhang, 2007) The current case study concluded that although NBA has achieved huge successes in the areas of building a large fan base, increasing media exposure, and garnering net income after its entry to China, it still faces many challenges. One viable solution for the NBA is to bring authentic American cultural commodities while adding Chinese characteristics to accommodate local fans. Combining global heroes such as Michael Jordan and Kobe Bryant and local hero such as Yao Ming, Yi Jianlian, and Jeremy Lin, NBA games will continue to appeal to millions of Chinese fans. Meantime, NBA management needs to continue seeking ways to work out and through the differences in government models and cultural contexts between China and United States. Some viable actions include the promotion of Chinese youth basketball, the training service for elite basketball players, and government-level public relations. In addition, this study suggested that the research framework of glocalization would be an ever intriguing inquiry needed for other sport organizations or leagues seeking expansion to overseas markets

Dolfin: Diffusion Layout Transformers without Autoencoder

In this paper, we introduce a novel generative model, Diffusion Layout Transformers without Autoencoder (Dolfin), which significantly improves the modeling capability with reduced complexity compared to existing methods. Dolfin employs a Transformer-based diffusion process to model layout generation. In addition to an efficient bi-directional (non-causal joint) sequence representation, we further propose an autoregressive diffusion model (Dolfin-AR) that is especially adept at capturing rich semantic correlations for the neighboring objects, such as alignment, size, and overlap. When evaluated against standard generative layout benchmarks, Dolfin notably improves performance across various metrics (fid, alignment, overlap, MaxIoU and DocSim scores), enhancing transparency and interoperability in the process. Moreover, Dolfin's applications extend beyond layout generation, making it suitable for modeling geometric structures, such as line segments. Our experiments present both qualitative and quantitative results to demonstrate the advantages of Dolfin