239 research outputs found
A Note on Stable States of Dipolar Systems at Low Temperatures
In the past several years, many important innovations in nanotechnology were
made. Today it becomes possible to make nanosize magnetic particles, and
development of high storage-density magnetic device is desired. In such a
magnetic particle system, dipole interaction plays the main role. In this note,
we consider stable states of dipolar systems at low temperature: Some systems
show ``antiferromagnetic structure'', and others show magnetic domain
structure, depending on lattice shapes.Comment: 5 pages including 5 eps figures, to appear in "Computer Simulation
Studies in Condensed Matter Physics XVIII", Eds. D. P. Landau, S. P. Lewis,
and H.-B. Sch\"{u}ttler (Springer Verlag, Heidelberg, Berlin
Finite dipolar hexagonal columns on piled layers of triangular lattice
We have investigated, by the Monte Carlo simulation, spin systems which
represent moments of arrayed magnetic nanoparticles interacting with each other
only by the dipole-dipole interaction. In the present paper we aim the
understanding of finite size effects on the magnetic nanoparticles arrayed in
hexagonal columns cut out from the close-packing structures or from those with
uniaxial compression. In columns with the genuine close-packing structures, we
observe a single vortex state which is also observed previously in finite
2-dimensional systems. On the other hand in the system with the inter-layer
distance set times of the close-packing one, we found ground
states which depend on the number of layers. The dependence is induced by a
finite size effect and is related to a orientation transition in the
corresponding bulk system.Comment: 3 pages, 2 figures. Proceedings of the International Conference on
Magnetism 2006 (ICM2006) conference. To appear in a special volume of Journal
of Magnetism and Magnetic Material
RustHorn: CHC-based Verification for Rust Programs (full version)
Reduction to the satisfiability problem for constrained Horn clauses (CHCs)
is a widely studied approach to automated program verification. The current
CHC-based methods for pointer-manipulating programs, however, are not very
scalable. This paper proposes a novel translation of pointer-manipulating Rust
programs into CHCs, which clears away pointers and memories by leveraging
ownership. We formalize the translation for a simplified core of Rust and prove
its correctness. We have implemented a prototype verifier for a subset of Rust
and confirmed the effectiveness of our method.Comment: Full version of the same-titled paper in ESOP202
Acceleration of probabilistic imaginary-time evolution method combined with quantum amplitude amplification
A probabilistic imaginary-time evolution (PITE) method was proposed as a
nonvariational method to obtain a ground state on a quantum computer. In this
formalism, the success probability of obtaining all imaginary-time evolution
operators acting on the initial state decreases as the imaginary time proceeds.
To alleviate the undesirable nature, we propose quantum circuits for PITE
combined with the quantum amplitude amplification (QAA) method. We reduce the
circuit depth in the combined circuit with QAA by introducing a
pre-amplification operator. We successfully demonstrated that the combination
of PITE and QAA works efficiently and reported a case in which the quantum
acceleration is achieved. Additionally, we have found that by optimizing a
parameter of PITE, we can reduce the number of QAA operations and that
deterministic imaginary-time evolution (deterministic ITE) can be achieved
which avoids the probabilistic nature of PITE. We applied the deterministic ITE
procedure to multiple imaginary-time steps and discussed the computational cost
for the circuits. Finally, as an example, we demonstrate the numerical results
of the PITE circuit combined with QAA in the first- and second-quantized
Hamiltonians.Comment: 20 pages, 12 figure
Quadratic acceleration of multi-step probabilistic algorithms for state preparation
For quantum state preparation, a non-unitary operator is typically designed
to decay undesirable states contained in an initial state using ancilla qubits
and a probabilistic action. Probabilistic algorithms do not accelerate the
computational process compared to classical ones. In this study, quantum
amplitude amplification (QAA) and multi-step probabilistic algorithms are
combined to achieve quadratic acceleration. This method outperforms quantum
phase estimation in terms of infidelity. The quadratic acceleration was
confirmed by the probabilistic imaginary-time evolution (PITE) method
A fundamental study assessing the generalized fitting method in conjunction with every possible coalition of N-combinations (G-EPOC) using the appendicitis detection task of computed tomography
Purpose: Increased use of deep learning (DL) in medical imaging diagnoses has led to more frequent use of 10-fold cross-validation (10-CV) for the evaluation of the performance of DL. To eliminate some of the (10-fold) repetitive processing in 10-CV, we proposed a "generalized fitting method in conjunction with every possible coalition of N-combinations (G-EPOC)", to estimate the range of the mean accuracy of 10-CV using less than 10 results of 10-CV. Material and methods: G-EPOC was executed as follows. We first provided (2N-1) coalition subsets using a specified N, which was 9 or less, out of 10 result datasets of 10-CV. We then obtained the estimation range of the accuracy by applying those subsets to the distribution fitting twice using a combination of normal, binominal, or Poisson distributions. Using datasets of 10-CVs acquired from the practical detection task of the appendicitis on CT by DL, we scored the estimation success rates if the range provided by G-EPOC included the true accuracy. Results: G-EPOC successfully estimated the range of the mean accuracy by 10-CV at over 95% rates for datasets with N assigned as 2 to 9. Conclusions: G-EPOC will help lessen the consumption of time and computer resources in the development of computer-based diagnoses in medical imaging and could become an option for the selection of a reasonable K value in K-CV
Borrowable Fractional Ownership Types for Verification
Automated verification of functional correctness of imperative programs with
references (a.k.a. pointers) is challenging because of reference aliasing.
Ownership types have recently been applied to address this issue, but the
existing approaches were limited in that they are effective only for a class of
programs whose reference usage follows a certain style. To relax the
limitation, we combine the approaches of ConSORT (based on fractional
ownership) and RustHorn (based on borrowable ownership), two recent approaches
to automated program verification based on ownership types, and propose the
notion of borrowable fractional ownership types. We formalize a new type system
based on the borrowable fractional ownership types and show how we can use it
to automatically reduce the program verification problem for imperative
programs with references to that for functional programs without references. We
also show the soundness of our type system and the translation, and conduct
experiments to confirm the effectiveness of our approach.Comment: An extended version of the paper to appear in Proceedings of VMCAI
202
"Double eyes” sign of congenital bilateral dacryocystoceles
Dacryocystocele is caused by nasolacrimal duct obstruction and results in cystic dilatation of the proximal part of the nasolacrimal duct, which is located inferomedial to the orbit, leading to fluid accumulation. It is important to consider that persistent congenital bilateral dacryocystoceles may cause neonatal nasal obstruction resulting in respiratory difficulty, and large dacryocystoceles may require surgical drainage. Ultrasonography demonstrates that congenital bilateral dacryocystoceles and normal eyeballs prenatally resemble two pairs of cystic "lesions” of different sizes. We herein present a case of prenatally diagnosed isolated congenital bilateral dacryocystoceles and propose the new name of "double eyes” sign for this rare condition to create an impact on medical students and resident
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