199 research outputs found

    Topological phases and delocalization of quantum walks in random environments

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    We investigate one-dimensional (1D) discrete time quantum walks (QWs) with spatially or temporally random defects as a consequence of interactions with random environments. We focus on the QWs with chiral symmetry in a topological phase, and reveal that chiral symmetry together with bipartite nature of the QWs brings about intriguing behaviors such as coexistence of topologically protected edge states at zero energy and Anderson transitions in the 1D chiral class at non-zero energy in their dynamics. Contrary to the previous studies, therefore, the spatially disordered QWs can avoid complete localization due to the Anderson transition. It is further confirmed that the edge states are robust for spatial disorder but not for temporal disorder.Comment: 7 pages, 7 figure

    Unveiling hidden topological phases of a one-dimensional Hadamard quantum walk

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    Quantum walks, whose dynamics is prescribed by alternating unitary coin and shift operators, possess topological phases akin to those of Floquet topological insulators, driven by a time-periodic field. While there is ample theoretical work on topological phases of quantum walks where the coin operators are spin rotations, in experiments a different coin, the Hadamard operator is often used instead. This was the case in a recent photonic quantum walk experiment, where protected edge states were observed between two bulks whose topological invariants, as calculated by the standard theory, were the same. This hints at a hidden topological invariant in the Hadamard quantum walk. We establish a relation between the Hadamard and the spin rotation operator, which allows us to apply the recently developed theory of topological phases of quantum walks to the one-dimensional Hadamard quantum walk. The topological invariants we derive account for the edge state observed in the experiment, we thus reveal the hidden topological invariant of the one-dimensional Hadamard quantum walk.Comment: 11 pages, 4 figure

    Stability of topologically protected edge states in nonlinear quantum walks: Additional bifurcations unique to Floquet systems

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    Recently, effects of nonlinearity on topologically nontrivial systems have attracted attention and the stability of topologically protected edge states has been studied for a quantum walk with nonlinear effects, which is akin to time-periodically driven systems (Floquet systems). In the previous work, it has been found that the edge states can be stable attractors or unstable repellers depending on their intrinsic topological property, while the stability is not affected by the strength of nonlinearity. In the present work, we find additional bifurcations at which edge states change from stable attractors to unstable repellers with increasing the strength of nonlinearity in nonlinear quantum walks, for the first time. The new bifurcations are unique to Floquet systems, since we take dynamical properties of Floquet systems into consideration by directly applying the time-evolution operator of the quantum walks to the linear stability analysis. Our results shed new light on nonlinear effects on topological edge states in Floquet systems.Comment: 28 pages, 11 figure

    Geochronological study of post-metamorphic granite from Kasumi Rock, Lutzow-Holm Complex, East Antarctica

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    Kasumi Rock is situated in the amphibolite-facies metamorphic zone in the Lutzow-Holm Complex, East Antarctica. In this area, granitic rocks occur as steeply dipping linear dykes with sharp intrusive contacts, and cross-cut the foliation of layered metamorphic rocks. A geochronological study of this post-metamorphic granite (PMG) has been performed. An Rb-Sr whole rock isochron for five granitic rocks defines an age of 492.1+-23.4 Ma with an initial ^87Sr/^86Sr ratio of 0.70535+-0.00027 (MSWD=0.08). In the Sm-Nd isochron diagram, four rock samples yield an age of 498.4+-90.6 Ma with an initial ^143Nd/^144Nd ratio of 0.511782+-0.000101 (MSWD=0.05). The whole rock isochron ages and mode of occurrence suggest that the Kasumi PMGs were intruded after regional cooling of the area, and probably affected local reequilibrium for isotopic systems of surrounding metamorphic rocks. The PMGs might have been slowly cooled and crystallized after the intrusion. The Kasumi PMGs have no genetic relation to the Oku-iwa PMGs as regards Rb-Sr and Sm-Nd isotopic systems, because the initial ratios of both PMGs are quite different from each other. This is interpreted to mean that the PMGs in the Lutzow-Holm Complex were originated from different source materials or had different chemical reaction processes with crustal materials

    Phase I clinical trial of the vaccination for the patients with metastatic melanoma using gp100-derived epitope peptide restricted to HLA-A*2402

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    <p>Abstract</p> <p>Background</p> <p>The tumor associated antigen (TAA) gp100 was one of the first identified and has been used in clinical trials to treat melanoma patients. However, the gp100 epitope peptide restricted to HLA-A*2402 has not been extensively examined clinically due to the ethnic variations. Since it is the most common HLA Class I allele in the Japanese population, we performed a phase I clinical trial of cancer vaccination using the HLA-A*2402 gp100 peptide to treat patients with metastatic melanoma.</p> <p>Methods</p> <p>The phase I clinical protocol to test a HLA-A*2402 gp100 peptide-based cancer vaccine was designed to evaluate safety as the primary endpoint and was approved by The University of Tokyo Institutional Review Board. Information related to the immunologic and antitumor responses were also collected as secondary endpoints. Patients that were HLA-A*2402 positive with stage IV melanoma were enrolled according to the criteria set by the protocol and immunized with a vaccine consisting of epitope peptide (VYFFLPDHL, gp100-in4) emulsified with incomplete Freund's adjuvant (IFA) for the total of 4 times with two week intervals. Prior to each vaccination, peripheral blood mononuclear cells (PBMCs) were separated from the blood and stored at -80°C. The stored PBMCs were thawed and examined for the frequency of the peptide specific T lymphocytes by IFN-γ- ELISPOT and MHC-Dextramer assays.</p> <p>Results</p> <p>No related adverse events greater than grade I were observed in the six patients enrolled in this study. No clinical responses were observed in the enrolled patients although vitiligo was observed after the vaccination in two patients. Promotion of peptide specific immune responses was observed in four patients with ELISPOT assay. Furthermore, a significant increase of CD8<sup>+ </sup>gp100-in4<sup>+ </sup>CTLs was observed in all patients using the MHC-Dextramer assay. Cytotoxic T lymphocytes (CTLs) clones specific to gp100-in4 were successfully established from the PBMC of some patients and these CTL clones were capable of lysing the melanoma cell line, 888 mel, which endogenously expresses HLA-restricted gp100-in4.</p> <p>Conclusion</p> <p>Our results suggest this HLA-restricted gp100-in4 peptide vaccination protocol was well-tolerated and can induce antigen-specific T-cell responses in multiple patients. Although no objective anti-tumor effects were observed, the effectiveness of this approach can be enhanced with the appropriate modifications.</p

    Novel Soft Meals Developed by 3D Printing

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    Recently, 3D printing is being applied to various fields. 3D printing of foods has been developed; however, there are many challenges. To overcome the challenges, we have started a new research group named “Yonezawa Itadakimasu Research Group,” to focus on the development of 3D printing applications for manufacturing food. We have developed Novel jelly foods that are shaped by 3D printed molds. Fused deposition modeling (FDM) 3D printer for food manufacturing makes the 3D printed molds. First step of making 3D printing mold is to print a cast. Then, food grade silicone is poured into the cast to make a mold. This type of 3D printed mold can be used widely, such as making sweets, restaurant menus, and care foods by changing the design depending on the use of application. Secondly, we started to develop 3D food printers. This type of challenge to develop future foods by 3D printing technology may have a major impact on the care food because the looks of foods are important and will be improved by 3D printing

    Radiologic Findings of IgG4-Related Disease

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    Autoimmune pancreatitis (AIP), characterized by an autoimmune phenomenon of prominent lymphocytes, IgG4-bearing plasma cell infiltration and storiform fibrosis, has been widely reported as a specific type of chronic pancreatitis. Typical image findings of this disease are reported as diffuse pancreatic swelling and a capsule-like rim on CT or MRI. However, AIP presents with a variable morphology, such as focal, segmental and multifocal swellings. Because imaging findings for AIP can look like those of pancreatic cancer, AIP has often been treated with unnecessary surgical resection. In addition, AIP is complicated by the involvement of various other organs besides the pancreas that show lymphoplasmacytic infiltration and fibrosis. These are frequently misdiagnosed as inherent lesions of corresponding organs. Furthermore, these extra-pancreatic lesions show systemic distribution and share common features of IgG4- bearing plasma cell infiltration as well as favorable responses to corticosteroid, indicating the presence of systemic condition, IgG4-related diseases. AIP is now recognized as an IgG4-related disease. Detailed evaluations of imaging findings of CT, MRI and Gallium-67 (Ga-67) scintigraphy for the involvement of these various organs are useful for a correct diagnosis of this systemic disease.ArticleCurrent Immunology Reviews. 7(2):186-203 (2011)journal articl

    Radiologic Findings of IgG4-Related Disease

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    Autoimmune pancreatitis (AIP), characterized by an autoimmune phenomenon of prominent lymphocytes, IgG4-bearing plasma cell infiltration and storiform fibrosis, has been widely reported as a specific type of chronic pancreatitis. Typical image findings of this disease are reported as diffuse pancreatic swelling and a capsule-like rim on CT or MRI. However, AIP presents with a variable morphology, such as focal, segmental and multifocal swellings. Because imaging findings for AIP can look like those of pancreatic cancer, AIP has often been treated with unnecessary surgical resection. In addition, AIP is complicated by the involvement of various other organs besides the pancreas that show lymphoplasmacytic infiltration and fibrosis. These are frequently misdiagnosed as inherent lesions of corresponding organs. Furthermore, these extra-pancreatic lesions show systemic distribution and share common features of IgG4- bearing plasma cell infiltration as well as favorable responses to corticosteroid, indicating the presence of systemic condition, IgG4-related diseases. AIP is now recognized as an IgG4-related disease. Detailed evaluations of imaging findings of CT, MRI and Gallium-67 (Ga-67) scintigraphy for the involvement of these various organs are useful for a correct diagnosis of this systemic disease.ArticleCurrent Immunology Reviews. 7(2):186-203 (2011)journal articl

    Characteristic findings in images of extra-pancreatic lesions associated with autoimmune pancreatitis

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    Purpose: Autoimmune pancreatitis is a unique form of chronic pancreatitis characterized by a variety of extra-pancreatic involvements which are frequently misdiagnosed as lesions of corresponding organs. The purpose of this study was to clarify the diagnostic imaging features of extra-pancreatic lesions associated with autoimmune pancreatitis. Materials and methods: We retrospectively analyzed diagnostic images of 90 patients with autoimmune pancreatitis who underwent computer-assisted tomography, magnetic resonance imaging, and/or gallium-67 scintigraphy before steroid therapy was initiated. Results: AIP was frequently (92.2%) accompanied by a variety of extra-pancreatic lesions, including swelling of lachrymal and salivary gland lesions (47.5%), lung hilar lymphadenopathy (78.3%), a variety of lung lesions (51.2%), wall thickening of bile ducts (77.8%), peri-pancreatic or para-aortic lymphadenopathy (56.0%), retroperitoneal fibrosis (19.8%), a variety of renal lesions (14.4%), and mass lesions of the ligamentum teres (2.2%). Characteristic findings in CT and MRI included lymphadenopathies of the hilar, peri-pancreatic, and para-aortic regions; wall thickening of the bile duct; and soft tissue masses in the kidney, ureters, aorta, paravertebral region, ligamentum teres, and orbit. Conclusions: Recognition of the diagnostic features in the images of various involved organs will assist in the diagnosis of autoimmune pancreatitis and in differential diagnoses between autoimmune pancreatitis-associated extra-pancreatic lesions and lesions due to other pathologies.ArticleEUROPEAN JOURNAL OF RADIOLOGY. 76(2):228-238 (2010)journal articl
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