Partial order in a frustrated Potts model

We investigate a 4-state ferromagnetic Potts model with a special type of geometrical frustration on a three dimensional diamond lattice by means of Wang-Landau Monte Carlo simulation motivated by a peculiar structural phase transition found in $\beta$-pyrochlore oxide KOs$_2$O$_6$. We find that this model undergoes unconventional first-order phase transition; half of the spins in the system order in a two dimensional hexagonal-sheet-like structure, while the remaining half stay disordered. The ordered sheets and the disordered sheets stack one after another. We obtain a fairly large residual entropy at $T = 0$ which originates from the disordered sheets.Comment: 7 pages, 8 figures, submitted to PR

Type-based Qubit Allocation for a First-Order Quantum Programming Language

Qubit allocation is a process to assign physical qubits to logical qubits in a quantum program. Since some quantum computers have connectivity constraints on applications of two-qubit operations, it is mainly concerned with finding an assignment and inserting instructions to satisfy the connectivity constraints. Many methods have been proposed for the qubit allocation problem for low-level quantum programs. This paper presents a type-based framework of qubit allocation for a quantum programming language with first-order functions. In our framework, the connectivity constraints are expressed by a simple graph of qubits called a coupling graph. We formalize (1) the source language, whose type system verifies that the number of qubits required for a given program to run does not exceed the number of nodes of the coupling graph, (2) the target language, whose qualified type system verifies that a well-typed program satisfies the connectivity constraints, and (3) an algorithm to translate a source program into a target program. We prove that both languages are type-safe and that the translation algorithm is type preserving.Comment: 15 pages + appendix, 10 figures, presented at PPL2022 (Japanese domestic conference

Neural Structure Fields with Application to Crystal Structure Autoencoders

Representing crystal structures of materials to facilitate determining them via neural networks is crucial for enabling machine-learning applications involving crystal structure estimation. Among these applications, the inverse design of materials can contribute to next-generation methods that explore materials with desired properties without relying on luck or serendipity. We propose neural structure fields (NeSF) as an accurate and practical approach for representing crystal structures using neural networks. Inspired by the concepts of vector fields in physics and implicit neural representations in computer vision, the proposed NeSF considers a crystal structure as a continuous field rather than as a discrete set of atoms. Unlike existing grid-based discretized spatial representations, the NeSF overcomes the tradeoff between spatial resolution and computational complexity and can represent any crystal structure. To evaluate the NeSF, we propose an autoencoder of crystal structures that can recover various crystal structures, such as those of perovskite structure materials and cuprate superconductors. Extensive quantitative results demonstrate the superior performance of the NeSF compared with the existing grid-based approach.Comment: 16 pages , 6 figures. 13 pages Supplementary Informatio

Endoscopic ultrasound-guided immunotherapy

AbstractAnti-tumoral endoscopic ultrasound-guided fine-needle injection (EUS-FNI), with its minimally invasive access for anti-tumoral agent delivery, is the most exciting field of intervention EUS. Pancreatic cancer is regarded as a systemic disease even if imaging modalities reveal no visible metastasis. From that perspective, immunological therapy is performed. To date, several reports have described immunotherapy under EUS-guidance. The first report of EUS-FNI intended for immunotherapy for advanced pancreatic cancer was published in 2000. In that study, an allogeneic mixed-lymphocyte culture was injected into tumors of eight patients with unresectable local pancreatic adenocarcinoma. The study of dendritic cells (DCs) for cancer has continued to develop in recent years. Actually, DCs are potent antigen-presenting cells for the induction of primary T-cell dependent immune response. When injected intratumorally, DCs acquire and process tumor antigens in situ, migrate to regional lymphoid organs, and initiate a strong tumor-specific immune response. To date, three reports have described EUS-FNI of DCs into pancreatic cancer: two for unresectable and one for pre-surgical operations. Every study has indicated the feasibility and safety. Furthermore, these reports showed that EUS-guided DCs injection might be an important option for treating advanced pancreatic cancer. EUS-guided immunotherapy is a very exciting field in interventional EUS for obstinate cancers

RVS for small lesion in hepatectomy

Background : Systemic chemotherapy can drastically downsize metastatic liver tumors and these small liver lesions could sometimes be difficult for surgeons to detect during hepatectomy. We assessed the usefulness of intraoperative real-time virtual sonography (RVS) with contrast-enhanced ultrasonography (CEUS) using ‘Sonazoid’ contrast agent (RVS-CEUS). Methods : We performed the intraoperative RVS-CEUS technique on 10 tumor lesions in six cases, which were scheduled for hepatic resection of < 10 mm in diameter in our liver metastases series. These lesions were preoperatively diagnosed by contrast enhanced-computed tomography (CE-CT) or Gadolinium-ethoxybenzyl-diethylenetriamine pentaacetic acid (Gd-EOB-DTPA)-enhanced magnetic resonance imaging (EOB-MRI). We assessed the detectability of a tumor with RVS-CEUS during surgery and compared it with that of preoperative CE-CT or EOB-MRI. Results : Detectability of RVS-CEUS for 10 small lesions was 90% (n = 9/10) and that of other preoperative modalities were 50% (n = 5/10, CE-CT) and 100% (n = 10/10, EOB-MRI). Minimum tumor size detected was 3.0 mm in diameter, and maximum depth of detection with RVS-CEUS was 43.5 mm ; these results could be an advantage when compared with other intraoperative diagnostic modalities. Conclusion : Intraoperative RVS-CEUS was useful for detecting small metastatic liver lesions after chemotherapy and could be an effective intraoperative diagnostic technique for hepatic resection of a size < 10 mm

Ground-state properties of the one-dimensional attractive Hubbard model with confinement: a comparative study

We revisit the one-dimensional attractive Hubbard model by using the Bethe-ansatz based density-functional theory and density-matrix renormalization method. The ground-state properties of this model are discussed in details for different fillings and different confining conditions in weak-to-intermediate coupling regime. We investigate the ground-state energy, energy gap, and pair-binding energy and compare them with those calculated from the canonical Bardeen-Cooper-Schrieffer approximation. We find that the Bethe-ansatz based density-functional theory is computationally easy and yields an accurate description of the ground-state properties for weak-to-intermediate interaction strength, different fillings, and confinements. In order to characterize the quantum phase transition in the presence of a harmonic confinement, we calculate the thermodynamic stiffness, the density-functional fidelity, and fidelity susceptibility, respectively. It is shown that with the increase of the number of particles or attractive interaction strength, the system can be driven from the Luther-Emery-type phase to the composite phase of Luther-Emery-like in the wings and insulating-like in the center.Comment: 13 pages with 10 figures and 2 table