Holographic Gubser-Rocha model does not capture all the transport anomalies of strange metals

In the last decade, motivated by the concept of Planckian relaxation and the possible existence of a quantum critical point in cuprate materials, holographic techniques have been extensively used to tackle the problem of strange metals and high-Tc superconductors. Among the various setups, the Gubser-Rocha model has often been celebrated as a successful holographic model for strange metals since endowed with the famous linear in $T$ resistivity property. As fiercely advocated by Phil Anderson, beyond $T$-linear resistivity, there are several additional anomalies unique to the strange metal phase, as for example a Fermi liquid like Hall angle -- the famous problem of the two relaxation scales. In this short note, we show that the holographic Gubser Rocha model fails in this respect and therefore, at least in its original and simplest form, is not able to capture the transport phenomenology of strange metals. We prove our statement by means of a direct numerical computation, a previously demonstrated scaling analysis and also a hydrodynamic argument. Finally, we conclude with an optimistic discussion on the possible improvements and generalizations which could lead to a holographic model for strange metals in all their glory.Comment: v1: 6 pages, 2 figure

Holography and magnetohydrodynamics with dynamical gauge fields

Within the framework of holography, the Einstein-Maxwell action with Dirichlet boundary conditions corresponds to a dual conformal field theory in presence of an external gauge field. Nevertheless, in many real-world applications, e.g., magnetohydrodynamics, plasma physics, superconductors, etc. dynamical gauge fields and Coulomb interactions are fundamental. In this work, we consider bottom-up holographic models at finite magnetic field and (free) charge density in presence of dynamical boundary gauge fields which are introduced using mixed boundary conditions. We numerically study the spectrum of the lowest quasi-normal modes and successfully compare the obtained results to magnetohydrodynamics theory in $2+1$ dimensions. Surprisingly, as far as the electromagnetic coupling is small enough, we find perfect agreement even in the large magnetic field limit. Our results prove that a holographic description of magnetohydrodynamics does not necessarily need higher-form bulk fields but can be consistently derived using mixed boundary conditions for standard gauge fields.Comment: 54 pages, 22 figure

Monte Carlo simulation-based defect ratio estimation approach for a chemical materials stockpile reliability program

A chemical material stockpile reliability program (CSRP) that determines the usability, safety, reliability, and performance of chemical equipment and materials is developed to determine the storage or disposal of chemical material stockpile (Storage Chemical Equipment and Material Reliability Evaluation Instruction, 2019). However, current inspection for current CSRP depend on test and evaluation of criteria for level of importance, and so the number of samples and acceptance quality limit (AQL) are presented based on the lot size. All the processes are conducted under KS Q ISO 2859-1, and the defect rate of the entire lot of CSRP items is generally assumed to be a distribution that is similar to a binomial distribution. However, the pass-fail test for CSRP items is based on approximately 10 test items, and the factors that cause defects in these items are also heterogeneous. We propose a new methodology for estimating the defect rates of CSRP items based on Monte Carlo simulations, which are widely used in various academic fields. In addition, we show the future applicability of the methodology by applying it to the K1 gas mask case and revealing the results of the defect rate estimation. We also present future work, including the need for a standard sample of CSRP items

Monte Carlo simulation-based defect ratio estimation approach for a chemical materials stockpile reliability program

A chemical material stockpile reliability program (CSRP) that determines the usability, safety, reliability, and performance of chemical equipment and materials is developed to determine the storage or disposal of chemical material stockpile (Storage Chemical Equipment and Material Reliability Evaluation Instruction, 2019). However, current inspection for current CSRP depend on test and evaluation of criteria for level of importance, and so the number of samples and acceptance quality limit (AQL) are presented based on the lot size. All the processes are conducted under KS Q ISO 2859-1, and the defect rate of the entire lot of CSRP items is generally assumed to be a distribution that is similar to a binomial distribution. However, the pass-fail test for CSRP items is based on approximately 10 test items, and the factors that cause defects in these items are also heterogeneous. We propose a new methodology for estimating the defect rates of CSRP items based on Monte Carlo simulations, which are widely used in various academic fields. In addition, we show the future applicability of the methodology by applying it to the K1 gas mask case and revealing the results of the defect rate estimation. We also present future work, including the need for a standard sample of CSRP items

Can We Utilize Pre-trained Language Models within Causal Discovery Algorithms?

Scaling laws have allowed Pre-trained Language Models (PLMs) into the field of causal reasoning. Causal reasoning of PLM relies solely on text-based descriptions, in contrast to causal discovery which aims to determine the causal relationships between variables utilizing data. Recently, there has been current research regarding a method that mimics causal discovery by aggregating the outcomes of repetitive causal reasoning, achieved through specifically designed prompts. It highlights the usefulness of PLMs in discovering cause and effect, which is often limited by a lack of data, especially when dealing with multiple variables. Conversely, the characteristics of PLMs which are that PLMs do not analyze data and they are highly dependent on prompt design leads to a crucial limitation for directly using PLMs in causal discovery. Accordingly, PLM-based causal reasoning deeply depends on the prompt design and carries out the risk of overconfidence and false predictions in determining causal relationships. In this paper, we empirically demonstrate the aforementioned limitations of PLM-based causal reasoning through experiments on physics-inspired synthetic data. Then, we propose a new framework that integrates prior knowledge obtained from PLM with a causal discovery algorithm. This is accomplished by initializing an adjacency matrix for causal discovery and incorporating regularization using prior knowledge. Our proposed framework not only demonstrates improved performance through the integration of PLM and causal discovery but also suggests how to leverage PLM-extracted prior knowledge with existing causal discovery algorithms

Association of pathway mutation with survival after recurrence in colorectal cancer patients treated with adjuvant fluoropyrimidine and oxaliplatin chemotherapy

Background Although the prognostic biomarkers associated with colorectal cancer (CRC) survival are well known, there are limited data on the association between the molecular characteristics and survival after recurrence (SAR). The purpose of this study was to assess the association between pathway mutations and SAR. Methods Of the 516 patients with stage III or high risk stage II CRC patients treated with surgery and adjuvant chemotherapy, 87 who had distant recurrence were included in the present study. We analyzed the association between SAR and mutations of 40 genes included in the five critical pathways of CRC (WNT, P53, RTK-RAS, TGF-β, and PI3K). Results Mutation of genes within the WNT, P53, RTK-RAS, TGF-β, and PI3K pathways were shown in 69(79.3%), 60(69.0%), 57(65.5%), 21(24.1%), and 19(21.8%) patients, respectively. Patients with TGF-β pathway mutation were younger and had higher incidence of mucinous adenocarcinoma (MAC) histology and microsatellite instability-high. TGF-β pathway mutation (median SAR of 21.6 vs. 44.4 months, p = 0.021) and MAC (20.0 vs. 44.4 months, p = 0.003) were associated with poor SAR, and receiving curative resection after recurrence was associated with favorable SAR (Not reached vs. 23.6 months, p <  0.001). Mutations in genes within other critical pathways were not associated with SAR. When MAC was excluded as a covariate, multivariate analysis revealed TGF-β pathway mutation and curative resection after distant recurrence as an independent prognostic factor for SAR. The impact of TGF-β pathway mutations were predicted using the PROVEAN, SIFT, and PolyPhen-2. Among 25 mutations, 23(92.0%)-24(96.0%) mutations were predicted to be damaging mutation. Conclusions Mutation in genes within TGF-β pathway may have negative prognostic role for SAR in CRC. Other pathway mutations were not associated with SAR.This research was supported by the Seoul National University Hospital (SNUH) Research Fund (03–2014-0440) and a grant of the Korea Health Technology R&D Project through the Korea Health Industry Development Institute (KHIDI), funded by the Ministry of Health & Welfare, Republic of Korea (grant number: HI14C1277 and HI13C2163). The funding bodies had no influence on the design of the study and collection, analysis, and interpretation of data and in writing the manuscript

Atomic-layer-confined multiple quantum wells enabled by monolithic bandgap engineering of transition metal dichalcogenides

Quantum wells (QWs), enabling effective exciton confinement and strong light-matter interaction, form an essential building block for quantum optoelectronics. For two-dimensional (2D) semiconductors, however, constructing the QWs is still challenging because suitable materials and fabrication techniques are lacking for bandgap engineering and indirect bandgap transitions occur at the multilayer. Here, we demonstrate an unexplored approach to fabricate atomic-layer-confined multiple QWs (MQWs) via monolithic bandgap engineering of transition metal dichalcogenides and van der Waals stacking. The WOX/WSe2 hetero-bilayer formed by monolithic oxidation of the WSe2 bilayer exhibited the type I band alignment, facilitating as a building block for MQWs. A superlinear enhancement of photoluminescence with increasing the number of QWs was achieved. Furthermore, quantum-confined radiative recombination in MQWs was verified by a large exciton binding energy of 193 meV and a short exciton lifetime of 170 ps. This work paves the way toward monolithic integration of band-engineered hetero-structures for 2D quantum optoelectronics