Magnetic Field-Induced Superconductor-Insulator-Metal Transition in an Organic Conductor: An Infrared Magneto-Optical Imaging Spectroscopy

The magnetic field-induced superconductor-insulator-metal transition (SIMT) in partially deuterated $\kappa$-(BEDT-TTF)$_2$Cu[N(CN)$_2$]Br, which is just on the Mott boundary, has been observed using the infrared magneto-optical imaging spectroscopy. The infrared reflectivity image on the sample surface revealed that the metallic (or superconducting) and insulating phases coexist and they have different magnetic field dependences. One of the magnetic field dependence is SIMT that appeared on part of the sample surface. The SIMT was concluded to originate from the balance of the inhomogenity in the sample itself and the disorder of the ethylene end groups resulting from fast cooling.Comment: 5 pages, 5 figures, to appear in Phys. Rev.

Vertically stacked graphene tunnel junction with structured water barrier

We report a vertically stacked graphene tunnel junction with an atomically thin insulating layer for novel function devices. The insulating water layer sandwiched between graphene samples as a tunnel barrier which is fabricated through deionized (DI) water treatment of epitaxial graphene. Two graphene samples fabricated by SiC thermal decomposition are directly bonded to each other in a face-to-face manner. Vertically stacked graphene samples without DI water treated formed an ohmic junction. By inserting the structured water layer as tunnel barrier, the stacked junction exhibits Direct tunneling (DT) characteristics in a low-electric-field regime and Fowler-Nordheim tunneling (FNT) characteristics in a high-electric-field regime. The thickness of the structured water layer is estimated to be 0.28 nm by fitting the FNT formula. The very thin structured water layer is stable as tunnel barrier on epitaxial graphene for diode devices, which will have a widely application in electronic devices

Mixing time and simulated annealing for the stochastic cellular automata

Finding a ground state of a given Hamiltonian on a graph $G=(V,E)$ is an important but hard problem. One of the potential approaches is to use a Markov chain Monte Carlo to sample the Gibbs distribution whose highest peaks correspond to the ground states. In this paper, we investigate a particular kind of stochastic cellular automata, in which all spins are updated independently and simultaneously. We prove that (i) if the temperature is fixed sufficiently high, then the mixing time is at most of order $\log|V|$, and that (ii) if the temperature drops in time $n$ as $1/\log n$, then the limiting measure is uniformly distributed over the ground states.Comment: 16 pages, 8 figure

Synthesized effective atomic numbers for commercially available dual-energy CT

Purpose: The objective of this study was to assess synthesized effective atomic number (Zeff) values with a new developed tissue characteristic phantom and contrast material of varying iodine concentrations using single-source fast kilovoltage switching dual-energy CT (DECT) scanner. Methods: A newly developed multi energy tissue characterisation CT phantom and an acrylic phantom with various iodine concentrations of were scanned using single-source fast kilovoltage switching DECT (GE-DECT) scanner. The difference between the measured and theoretical values of Zeff were evaluated. Additionally, the difference and coefficient of variation (CV) values of the theoretical and measured values were compared with values obtained with the Canon-DECT scanner that was analysed in our previous study. Results: The average Zeff difference in the Multi-energy phantom was within 4.5%. The average difference of the theoretical and measured Zeff values for the acrylic phantom with variation of iodine concentration was within 3.3%. Compared to the results for the single-source Canon-DECT scanner used in our previous study, the average difference and CV of the theoretical and measured Zeff values obtained with the GE-DECT scanner were markedly smaller. Conclusions: The accuracy of the synthesized Zeff values with GE-DECT had a good agreement with the theoretical Zeff values for the Multi-Energy phantom. The GE-DECT could reduce the noise and the accuracy of the Zeff values than that with Canon-DECT for the varying iodine concentrations of contrast medium. Advances in knowledge: The accuracy and precision of the Zeff values of the contrast medium with the GE-DECT could be sufficient with human equivalent materials

Tiam1 interaction with the PAR complex promotes talin-mediated Rac1 activation during polarized cell migration.

Migrating cells acquire front-rear polarity with a leading edge and a trailing tail for directional movement. The Rac exchange factor Tiam1 participates in polarized cell migration with the PAR complex of PAR3, PAR6, and atypical protein kinase C. However, it remains largely unknown how Tiam1 is regulated and contributes to the establishment of polarity in migrating cells. We show here that Tiam1 interacts directly with talin, which binds and activates integrins to mediate their signaling. Tiam1 accumulated at adhesions in a manner dependent on talin and the PAR complex. The interactions of talin with Tiam1 and the PAR complex were required for adhesion-induced Rac1 activation, cell spreading, and migration toward integrin substrates. Furthermore, Tiam1 acted with talin to regulate adhesion turnover. Thus, we propose that Tiam1, with the PAR complex, binds to integrins through talin and, together with the PAR complex, thereby regulates Rac1 activity and adhesion turnover for polarized migration

Doppler ultrasound findings correlate with tissue vascularity and inflammation in surgical pathology specimens from patients with small intestinal Crohn’s disease

BACKGROUND: Crohn’s disease (CD) is routinely evaluated using clinical symptoms, laboratory variables, and the CD activity index (CDAI). However, clinical parameters are often nonspecific and do not precisely reflect the actual activity of CD small-intestinal lesions. The purposes of this prospective study were to compare color Doppler ultrasound (US) findings with histological findings from surgically resected specimens and confirm the hypothesis that color Doppler US can distinguish tissue inflammation and fibrosis. METHODS: Among 1764 consecutive patients who underwent color Doppler US examinations, 10 patients with CD (12 small-intestinal CD lesions) who underwent US examinations before elective small-intestine resection were evaluated in the present study. Areas of thickened intestinal walls were evaluated in terms of blood flow using color Doppler US imaging. The blood flow was semiquantitatively classified as “hyper-flow” and “hypo-flow” according to the Limberg score. Resected lesions were macroscopically and histopathologically processed. Inflammatory cell infiltration, fibrosis and vascularity were evaluated by myeloperoxidase (granulocytes), CD163 (macrophages), CD79a (B cells), CD3 (T cells), Masson’s trichrome (fibrosis), and factor VIII staining (vascular walls). All histopathological images were entered into virtual slide equipment and quantified using a quantitative microscopy integrated system (TissueMorph™). RESULTS: There were no significant differences in disease features or laboratory findings between “hypo-flow” lesions (n = 4) and “hyper-flow” lesions (n = 8). Histopathologically, “hyper-flow” lesions showed significantly greater bowel wall vascularity (factor VIII) (p = 0.047) and inflammatory cell infiltration, including CD163 macrophages (p = 0.008), CD3 T cells, and CD79a B cells (p = 0.043), than did “hypo-flow” lesions. There was no apparent association between the blood flow and CDAI. CONCLUSIONS: In this study, active CD lesions were macroscopically visible in surgical specimens of patients with increased blood flow on preoperative color Doppler US imaging. Additionally, these CD lesions exhibited significantly greater vascularity and numbers of inflammatory leukocytes microscopically. Color Doppler US may predict tissue inflammation and fibrosis in small-intenstinal CD lesions

Unusual endoscopic findings of gastric neuroendocrine tumor

Gastric neuroendocrine tumor (NET) is sometimes found as a submucosal tumor on upper gastrointestinal endoscopy. Gastric NET with malignant profile and neuroendocrine carcinoma (NEC) show various forms which are difficult to distinguish from gastric cancer and other disease. We report a case of a cauliflower-shaped NET of the stomach. A 61-year-old man was referred to our hospital with a complaint of abdominal fullness. Upper gastrointestinal endoscopic examination revealed an unusual, whitish cauliflower-shaped tumor that belongs to Borrmann type I on the lesser curvature of the gastric antrum. Histological examination of the biopsy specimen revealed NET G2, because the tumor cells were CD56- and synaptophysin-positive by immunohistochemical analysis. A distal gastrectomy with D2 lymphadenectomy was performed. A recurrence in the liver was revealed by follow up computed tomography after 11 months from operation. Combined chemotherapy with irinotecan (CPT-11) plus cisplatin (CDDP) was treated. The patient achieved a partial response, but he died after 31 months from gastrectomy. There is no independent, large-scaled prospective study and no standard treatment for gastric NETs with distant metastases. Our case is reported with a literature review of the treatment of metastatic gastric NET G2