Achieving the Optimal Steaming Capacity and Delay Using Random Regular Digraphs in P2P Networks

In earlier work, we showed that it is possible to achieve $O(\log N)$ streaming delay with high probability in a peer-to-peer network, where each peer has as little as four neighbors, while achieving any arbitrary fraction of the maximum possible streaming rate. However, the constant in the $O(log N)$ delay term becomes rather large as we get closer to the maximum streaming rate. In this paper, we design an alternative pairing and chunk dissemination algorithm that allows us to transmit at the maximum streaming rate while ensuring that all, but a negligible fraction of the peers, receive the data stream with $O(\log N)$ delay with high probability. The result is established by examining the properties of graph formed by the union of two or more random 1-regular digraphs, i.e., directed graphs in which each node has an incoming and an outgoing node degree both equal to one

Neoliberalism and the Politics of Social Enterprises in South Korea: The Dynamics of Neoliberal Governmentality and Hegemony

Social enterprises have been promoted globally as alternative economic institutions to neoliberalism for the last few decades. In this study, I explored how social enterprises and the subjectivities of social entrepreneurs emerged as new discursive formations and institutional mechanisms in the neoliberal transformation of governance strategies in South Korea. Three broader questions guide this study. First, how have social enterprises emerged as a new discursive formation and a new institutional mechanism in neoliberal South Korean society? Second, how are the new subjectivities of social entrepreneurs produced in ways that are consistent with neoliberalism? Finally what are the implications of the emergence of social enterprises and the subjectivities of social entrepreneurs in terms of the neoliberal transformations of South Korean society? I situated these research questions within the theoretical frameworks of Neo-Marxist social theory and Foucauldian governmentality theory. In order to answer these questions, I analyzed newspaper articles, South Korean governmental policy reports, academic journal articles, and guidebooks for social entrepreneurs. I argue that the promotion of social enterprises operates as a new neoliberal government strategy that captures anti-neoliberal progressive social movements and shifts the responsibilities of the state for solving particularly problems of poverty and unemployment onto civil society and social activists. Central findings demonstrate that, despite the pervasiveness of the statements of progressive social movements—solidarity, public good, feminist empowerment, and social change—in the discourses of social enterprises, these statements are dominated by the logic and principles of the market regardless of the discourse producers’ political orientations. In forming the partnership with progressive social movement forces, state power mobilizes them into the mechanisms to promote social enterprises. Social activists are encouraged to be professional social entrepreneurs by arming themselves with an entrepreneurial spirit, knowledge of business administration, and a sense of responsibility for the disadvantaged. Theoretically, this study has broader implications in terms of its exploration of new neoliberal governance mechanisms inscribed in the promotion of social enterprises and social entrepreneurs. This study also has important practical implications insofar as it reveals how Korean progressive leftists are unintentionally allied with neoliberalism, and thereby ironically reinforce its hegemony

Alternative splicing and extra-telomeric role of telomerase reverse transcriptase isoforms in human embryonic stem cells

Human telomerase, a ribonucleoprotein complex consisting of a catalytic subunit (hTERT) and a RNA template component (TERC), prevents telomere attrition in human embryonic stem cells (hESCs) providing these cells with prolonged replicative capacity. Interestingly, hTERT has several alternatively spliced isoforms, most of which are catalytically inactive. One alternative splicing event involving a complete loss of exons 7 and 8 results in a catalytically inactive isoform called β-hTERT. The β-hTERT is highly expressed in certain cancer types and hESCs. Full-length hTERT (FL-hTERT) is known to translocate from nuclei to mitochondria when cells are exposed to either chronic (oxygen tension) or acute (hydrogen peroxide) oxidative stress. In this study, I examined the alternative splicing of endogenous hTERT transcript in hESC, intra-cellular localization of FL-hTERT and β-hTERT in hESCs, and the effect of overexpressing recombinant hTERT on hESC mitochondria. Human ESCs (HES2 line) were cultured under 2% oxygen and 3xFLAG tagged FL-hTERT and β-hTERT were induced by doxycycline prior to 100μM H2O2 treatment. My results demonstrate that overexpression of transgenic FL-hTERT resulted in a significant increase in endogenous β-hTERT transcript level. Additionally, doxycycline and H2O2 altered the splicing pattern of hTERT in favor of β-hTERT. I demonstrate that not only the full-length- but also β-hTERT can bind TERC, and that β-hTERT overexpression inhibits telomerase activity in vitro. However, I failed to observe the mitochondrial localization of recombinant FL-hTERT or β-hTERT. Lastly, my results demonstrate the pro-apoptotic role of β-hTERT and the pro-survival effect of FL-hTERT under H2O2-induced oxidative stress

The role of telomeres and telomerase reverse transcriptase isoforms in pluripotency induction and maintenance

Telomeres are linear guanine-rich DNA structures at the ends of chromosomes. The length of telomeric DNA is actively regulated by a number of mechanisms in highly proliferative cells such as germ cells, cancer cells, and pluripotent stem cells. Telomeric DNA is synthesized by way of the ribonucleoprotein called telomerase containing a reverse transcriptase (TERT) subunit and RNA component (TERC). TERT is highly conserved across species and ubiquitously present in their respective pluripotent cells. Recent studies have uncovered intricate associations between telomeres and the self-renewal and differentiation properties of pluripotent stem cells. Interestingly, the past decade\u27s work indicates that the TERT subunit also has the capacity to modulate mitochondrial function, to remodel chromatin structure, and to participate in key signaling pathways such as the Wnt/β-catenin pathway. Many of these non-canonical functions do not require TERT\u27s catalytic activity, which hints at possible functions for the extensive number of alternatively spliced TERT isoforms that are highly expressed in pluripotent stem cells. In this review, some of the established and potential routes of pluripotency induction and maintenance are highlighted from the perspectives of telomere maintenance, known TERT isoform functions and their complex regulation

NFTs to MARS: Multi-Attention Recommender System for NFTs

Recommender systems have become essential tools for enhancing user experiences across various domains. While extensive research has been conducted on recommender systems for movies, music, and e-commerce, the rapidly growing and economically significant Non-Fungible Token (NFT) market remains underexplored. The unique characteristics and increasing prominence of the NFT market highlight the importance of developing tailored recommender systems to cater to its specific needs and unlock its full potential. In this paper, we examine the distinctive characteristics of NFTs and propose the first recommender system specifically designed to address NFT market challenges. In specific, we develop a Multi-Attention Recommender System for NFTs (NFT-MARS) with three key characteristics: (1) graph attention to handle sparse user-item interactions, (2) multi-modal attention to incorporate feature preference of users, and (3) multi-task learning to consider the dual nature of NFTs as both artwork and financial assets. We demonstrate the effectiveness of NFT-MARS compared to various baseline models using the actual transaction data of NFTs collected directly from blockchain for four of the most popular NFT collections. The source code and data are available at https://anonymous.4open.science/r/RecSys2023-93ED

Visual discomfort with stereo displays: Effects of viewing distance and direction of vergence-accommodation conflict

ABSTRACT Prolonged use of conventional stereo displays causes viewer discomfort and fatigue because of the vergenceaccommodation conflict. We used a novel volumetric display to examine how viewing distance and the sign of the vergence-accommodation conflict affect discomfort and fatigue. In the first experiment, we presented a fixed conflict at short, medium, and long viewing distances. We compared subjects' symptoms in that condition and one in which there was no conflict. We observed more discomfort and fatigue with a given vergence-accommodation conflict at the longer distances. The second experiment compared symptoms when the conflict had one sign compared to when it had the opposite sign at short, medium, and long distances. We observed greater symptoms with uncrossed disparities at long distances and with crossed disparities at short distances. These findings help define comfortable viewing conditions for stereo displays

Modification of argon impurity transport by electron cyclotron heating in KSTAR H-mode plasmas

Experiments with a small amount of Ar gas injection as a trace impurity were conducted in the Korea Superconducting Tokamak Advanced Research (KSTAR) H-mode plasma (BT  = 2.8 T, IP = 0.6 MA, and PNBI = 4.0 MW). 170 GHz electron cyclotron resonance heating (ECH) at 600 and 800 kW was focused along the mid-plane with a fixed major radial position of R  =  1.66 m. The emissivity of the Ar16+ (3.949 Å) and Ar15+ (353.860 Å) spectral lines were measured by x-ray imaging crystal spectroscopy (XICS) and a vacuum UV (VUV) spectrometer, respectively. ECH reduces the peak Ar15+ emission and increases the Ar16+ emission, an effect largest with 800 kW. The ADAS-SANCO impurity transport code was used to evaluate the Ar transport coefficients. It was found that the inward convective velocity found in the plasma core without ECH was decreased with ECH, while diffusion remained approximately constant resulting in a less-peaked Ar density profile. Theoretical results from the NEO code suggest that neoclassical transport is not responsible for the change in transport, while the microstability analysis using GKW predicts a dominant ITG mode during both ECH and non-ECH plasmas

Study of Intense Proton Beams: Generation and Transport in Solid Density Matter

Intense proton beams are appealing research subjects in high energy density physics and fast ignition of inertial confinement fusion as they are advantageous to isochoric heating and local energy deposition deep in the medium. A leading method for generation of proton beams utilizes high-power lasers to accelerate protons to energies over MeV. For applications, generation of these intense beams must be controlled, and understanding of the physics of beam transport in a new intensity regime is required. This thesis contains experimental findings, as well as computational studies, on the generation of intense proton beams and their transport in solid density matter. Experiments were carried out to compare proton beam focusing from different target geometries irradiated by an intense laser. Compared to a free standing target, enclosed targets show a narrower and brighter K-alpha radiation emission spot on a foil placed behind the target, indicating higher beam focusability. Numerical simulations have confirmed that the cause of the experimentally measured focusing effect is a field on the target enclosing structures. Furthermore, the long laser pulse duration (10 ps) was beneficial to keep providing radial electric fields for beam focusing. This thesis presents a simulation of the transport and energy deposition for such an intense proton beam in solid-density matter, where both collective effects and the individual proton slowing-down are taken into account in a self-consistent, dynamically coupled manner. To achieve this, a new proton stopping power module covering warm dense matter states has been implemented in the hybrid PIC code LSP where the proton stopping power is updated with the varying local target thermodynamic state at each simulation grid and time step. Detailed analyses were undertaken to comprehend the collective effects taking place in these system. As an example, a self-generated magnetic field can develop during beam transport at high current density. In the case of a narrow beam, it can be strong enough to pinch the beam, leading to the local target heating up to hundreds of eV. Finally, simulations showing consistent results with experimental data demonstrate that varying stopping power in different materials during proton beam transport can significantly alter the target heating profiles