156 research outputs found
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 -pyrochlore oxide KOsO. 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 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
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