Optical conductivity of black phosphorus with a tunable electronic structure

Black phosphorus (BP) is a two-dimensional layered material composed of phosphorus atoms. Recently, it was demonstrated that external perturbations such as an electric field close the band gap in few-layer BP, and can even induce a band inversion, resulting in an insulator phase with a finite energy gap or a Dirac semimetal phase characterized by two separate Dirac nodes. At the transition between the two phases, a semi-Dirac state appears in which energy disperses linearly along one direction and quadratically along the other. In this work, we study the optical conductivity of few-layer BP using a lattice model and the corresponding continuum model, incorporating the effects of an external electric field and finite temperature. We find that the low-frequency optical conductivity scales a power law that differs depending on the phase, which can be utilized as an experimental signature of few-layer BP in different phases. We also systematically analyze the evolution of the material parameters as the electric field increases, and the consequence on the power-law behavior of the optical conductivity.Comment: 14 pages, 11 figure

Robust Multi-bit Natural Language Watermarking through Invariant Features

Recent years have witnessed a proliferation of valuable original natural language contents found in subscription-based media outlets, web novel platforms, and outputs of large language models. However, these contents are susceptible to illegal piracy and potential misuse without proper security measures. This calls for a secure watermarking system to guarantee copyright protection through leakage tracing or ownership identification. To effectively combat piracy and protect copyrights, a multi-bit watermarking framework should be able to embed adequate bits of information and extract the watermarks in a robust manner despite possible corruption. In this work, we explore ways to advance both payload and robustness by following a well-known proposition from image watermarking and identify features in natural language that are invariant to minor corruption. Through a systematic analysis of the possible sources of errors, we further propose a corruption-resistant infill model. Our full method improves upon the previous work on robustness by +16.8% point on average on four datasets, three corruption types, and two corruption ratios. Code available at https://github.com/bangawayoo/nlp-watermarking.Comment: ACL 2023 lon

Models and Benchmarks for Representation Learning of Partially Observed Subgraphs

Subgraphs are rich substructures in graphs, and their nodes and edges can be partially observed in real-world tasks. Under partial observation, existing node- or subgraph-level message-passing produces suboptimal representations. In this paper, we formulate a novel task of learning representations of partially observed subgraphs. To solve this problem, we propose Partial Subgraph InfoMax (PSI) framework and generalize existing InfoMax models, including DGI, InfoGraph, MVGRL, and GraphCL, into our framework. These models maximize the mutual information between the partial subgraph's summary and various substructures from nodes to full subgraphs. In addition, we suggest a novel two-stage model with $k$-hop PSI, which reconstructs the representation of the full subgraph and improves its expressiveness from different local-global structures. Under training and evaluation protocols designed for this problem, we conduct experiments on three real-world datasets and demonstrate that PSI models outperform baselines.Comment: CIKM 2022 Short Paper (Camera-ready + Appendix

CVD-grown monolayer MoS2 in bioabsorbable electronics and biosensors

Transient electronics entails the capability of electronic components to dissolve or reabsorb in a controlled manner when used in biomedical implants. Here, the authors perform a systematic study of the processes of hydrolysis, bioabsorption, cytotoxicity and immunological biocompatibility of monolayer MoS2

Measuring Anxiety in Patients With Early-Stage Parkinson's Disease: Rasch Analysis of the State-Trait Anxiety Inventory

The State-Trait Anxiety Inventory (STAI), composed of two 20-item subscales (STAI-state and STAI-trait), has been increasingly used to assess anxiety symptoms in patients with Parkinson's disease (PD). However, the clinimetric attributes of the STAI under the statistical framework of the item-response theory (IRT) have not been fully elucidated within this population to date. We performed an IRT-based Rasch analysis of the STAI outcomes of patients with de novo PD from the Parkinson's Progression Markers Initiative database. The unidimensionality, Rasch model fit, scale targeting, separation reliability, differential item functioning, and response category utility of the STAI were statistically evaluated. A total of 326 (209 males, 117 females) patients without cognitive dysfunction were enrolled in our study. The original versions of the STAI-state and STAI-trait had acceptable separation reliability but lacked appropriate response category functioning, exhibited scale off-targeting, and several items demonstrated poor fit to the Rasch model. The response categories were reduced from four to three, and the rescored three-point TASI-trait demonstrated a marked improvement in clinimetric properties without a significant impact on unidimensionality and separation reliability. The rescored three-point version of the STAI-state required the additional removal of four misfitting items in order to improve the Rasch model fit. To our knowledge, this is the first study to assess the measurement properties based on the IRT of the STAI in patients with PD. Our Rasch analysis identified the components requiring possible amendments in order to improve the clinimetric attributes of the STAI

Comparative study about public administration between the FRG and the GDR

Die vorliegende Dissertationsschrift untersucht die Mentalitäten der Verwaltungstätigen und die Verwaltungssysteme der Bundesrepublik Deutschland und der Deutschen Demokratischen Republik. Der erste Teil dieser Arbeit untersucht die Auswirkungen des jeweiligen Verwaltungssystems auf die Mentalitäten der Verwaltungstätigen. Im Kapitel drei und Kapitel vier werden die Verwaltungsorganisationen und die jeweilige Personalverwaltung der Bundesrepublik Deutschland und der Deutschen Demokratischen Republik neben der Entstehung und der Entwicklung des Verwaltungsfeldes behandelt. Im Kapitel fünf wird anhand der Ergebnisse einer Interviewanalyse die Mentalität der Verwaltungstätigen mit dem jeweiligen Verwaltungsfeld verknüpft. Diese Untersuchungsanordnung soll die Ergebnisse des Kapitels drei und Kapitels vier bestätigen. Die Ergebnisse der Interviewanalyse lassen sich wie folgt zusammenfassen. Die vertikale Abhängigkeit der Staatsfunktionäre ist für die Mentalität der DDR-Verwaltungstätigen zentral. Das vertikale Abhängigkeitsverhältnis schwächte die Abhängigkeit des DDR-Verwaltungsfeldes vom Recht. Die Kontrolle der DDR-Verwaltungstätigen, der Staatfunktionäre erfolgte durch die Planerfüllung. In Angrenzung hierzu hat das BRD- Verwaltungsfeld relativ horizontale Verhältnisse. Dies spiegelt sich in der Mentalität der BRD-Verwaltungstätigen, den Beamten wider. Der Begriff des Rechtsstaates und die individuelle Arbeitskultur trugen dazu bei, das Verwaltungsfeld dezentral aufzubauen.This study examines the Mentality of civil servants as well as the system of public administration in the German Democratic Republic and in the Federal Republic of Germany. The study uses two theories, 'New Institutionalism' and 'Practice Theory' which were created by French sociologist Bourdieu. In chapter 2, if how die mutual relation between the mentality of civil servant and the public administrative System was connected, according this the public administrative system as a external System could be expressed through the statements of the civil servant. this is externalization of a internalized System. In Chapters three and four of this study, outside of the historical analysis of a public administrative field in the both East and West Germanys public administrative organizations and personnel administration are dealt with. Chapter five deals with the internalization of the external system through the body of the civil servants. The internalization of the external system was expressed through the daily life of civil servants from the way they think, attitude, to their statements. According to this, the interviews of civil servants in both countries can confirm the Mentality of civil servant as internalized external system. The result of the interview analysis is the same as the next. The formation of mentality of civil servant in the German Democratic Republic played a vital role in the leading role of a Marxian party and democratic centralization. It was confirmed that East Germany put importance on vertical relation and the orders of superiors at the public administration. Characteristics in the public administrative System have influenced the formation of the mentality of civil servant in the German Democratic Republic. On the contrary to the public administrative system in the German Democratic Republic die public administration in the Federal Republic of Germany moves toward the horizontal relationship between civil servants and their superior

Optical conductivity of black phosphorus with a tunable electronic structure

© 2019 IOP Publishing Ltd. Black phosphorus (BP) is a two-dimensional layered material composed of phosphorus atoms. Recently, it was demonstrated that external perturbations such as an electric field close the band gap in few-layer BP, and can even induce a band inversion, resulting in an insulator phase with a finite energy gap or a Dirac semimetal phase characterized by two separate Dirac nodes. At the transition between the two phases, a semi-Dirac state appears in which energy disperses linearly along one direction and quadratically along the other. In this work, we study the optical conductivity of few-layer BP using a lattice model and the corresponding continuum model, incorporating the effects of an external electric field and finite temperature. We find that the low-frequency optical conductivity scales a power law that differs depending on the phase, which can be utilized as an experimental signature of few-layer BP in different phases. We also systematically analyze the evolution of the material parameters as the electric field increases, and the consequence on the power-law behavior of the optical conductivit

Electromagnetic analysis of a stripline array of slot radiators

A two-dimensional (2D) periodic array of slot radiators excited by strip transmission lines is analyzed. A boundary value problem (which is then reduced to a system of integral equations for equivalent magnetic currents in the slots) is formulated. Expressions for the array scattering matrix and radiation parameters (radiation pattern and gain) are derived. An algorithm for numerical solution of the boundary value problem is developed. Various array operation modes are analyzed