Attosecond Transient Absorption Spectroscopy of Strongly Correlated Mott Insulators: Signature of the Creation and Annihilation of Double Occupancy

We applied the time-resolved attosecond transient absorption spectroscopy to systematically investigate ultrafast optical responses of condensed matter systems. Under an intense pump pulse, absorption spectra indicate that the non-interacting electrons of band insulators produce a field-induced redshift, known as the dynamical Franz-Keldysh effect, as commonly expected. In contrast to the band insulators, in Mott insulators, unconventional spectra are observed which do not fully reflect the dynamical Franz-Keldysh effect. While it still exhibits the fishbone-like structures mimicking the dynamical Franz-Keldysh effect, the spectra show a negative difference absorption below the band edge, rendering a blueshift. In addition, the decomposed difference absorption reveals the creation and the annihilation of double occupancy mainly contribute to the negative signal, implying that the unconventional spectra are purely driven by the electron-correlations. These demonstrations of unconventional responses would guide us to the correlation-embedded attosecond electron dynamics in condensed matter systems.Comment: 7 pages, 8 figure

Amerikorean

"Amerikorean" is a project that utilizes imagery to elucidate the struggles of an immigrant from South Korea attempting to adjust and define a sense of identity in the United States. The image-making process represents an examination of American cultural, political, and social standards, and contains emotions, thoughts and humor to initiate and promote a productive discussion about the complex subject of immigration. This is a timely topic in the current American political climate. As an immigrant who struggles with communication, my intent is also to share with my viewers the emotional and social distress associated with communication barriers encountered daily through imagery, which is often easier than with words. The main purpose of this study is to define my dual identities as an immigrant: Korean and American, foreign and native, adjusted and never adjusting. The attempt is to provide a voice to all of those who, define themselves as foreign or an "other" in American society

Forecasting Waste Agricultural Plastics Generation in the Republic of Korea and its Policy Implications

The generation of waste plastics mulch is predicted to decline after 2019 and then stabilize at around 200,000 tons per year. This is within the current gross treatment capacity of private and public facilities. However, the Korean Waste Agricultural Plastics (WAP) management system is vulnerable to market uncertainty, which might lead to uncontrollable accumulation of untreated waste plastics as experienced in 2005. Shifting from the KECO (Korea Environment Corporation)-led system to a more flexible market-oriented system is recommended

A Robust Fault-Tolerant and Scalable Cluster-wide Deduplication for Shared-Nothing Storage Systems

Deduplication has been largely employed in distributed storage systems to improve space efficiency. Traditional deduplication research ignores the design specifications of shared-nothing distributed storage systems such as no central metadata bottleneck, scalability, and storage rebalancing. Further, deduplication introduces transactional changes, which are prone to errors in the event of a system failure, resulting in inconsistencies in data and deduplication metadata. In this paper, we propose a robust, fault-tolerant and scalable cluster-wide deduplication that can eliminate duplicate copies across the cluster. We design a distributed deduplication metadata shard which guarantees performance scalability while preserving the design constraints of shared- nothing storage systems. The placement of chunks and deduplication metadata is made cluster-wide based on the content fingerprint of chunks. To ensure transactional consistency and garbage identification, we employ a flag-based asynchronous consistency mechanism. We implement the proposed deduplication on Ceph. The evaluation shows high disk-space savings with minimal performance degradation as well as high robustness in the event of sudden server failure.Comment: 6 Pages including reference