1,856 research outputs found

    Low-energy Spectra of the t-J-Type Models Studied by Variational Approach

    Full text link
    We discuss recent progress of understanding the phenomena observed in high Tc cuprates by studying the d-wave resonating-valence-bond (d-RVB) based trial wave functions for the 2-dimensional t-J-type models. Treat exactly the strong correlation between electrons by numerical approach, we examine the evolution of ground states described by different variational wave functions and properties of the quasi-hole and -particle excitations of the d-RVB superconducting (SC) state. Properties related to the Fermi surface geometry deduced from quasi-hole energy dispersion of the SC state is shown to be consistent with the observation by photoemission spectroscopy. With the calculated spectral weights (SW's) for adding and removing an electron, we found not only the anti-correlation between conductance peak height and width between peaks seen in tunneling experiments, but also unique properties due to strong correlation which need to be verified by future experiments.Comment: 6 revtex pages with 5 (.eps) figures. To appear in a special volume of Journal of Magnetism and Magnetic Materials for the ICM 2006 proceeding

    Comparative Hydrodynamics Study in a Bubble Column using Computer-Automated Radioactive Particle Tracking (CARPT)/computed Tomography (CT) and Particle Image Velocimetry (PIV)

    Get PDF
    The Hydrodynamics of a 10-Cm-Diameter Cylindrical Bubble Column at the Superficial Gas Velocity of 2, 4, and 8 Cm/s Are Investigated by Computer-Automated Radioactive Particle Tracking (CARPT), Particle Image Velocimetry (PIV), and Computed Tomography (CT). These Experimental Techniques Are Capable of Providing the Knowledge of Velocity and Holdup Fields in a Bubble Column System, Which Are Essential as the Experimental Benchmark for Modeling of Such Systems. the Flow Field of Liquid Phase, as Well as the Reynolds Stresses, Obtained by CARPT and PIV in an Air-Water System Are Compared in Detail. the Results Indicate that CARPT and PIV Complement Each Other Well. Further, the Profile of Gas Holdup Obtained by Gamma Ray based on CT Compares Favorably to the Independently Determined Holdup

    Hyperbaric oxygen suppressed tumor progression through the improvement of tumor hypoxia and induction of tumor apoptosis in A549-cell-transferred lung cancer

    Get PDF
    Tumor cells have long been recognized as a relative contraindication to hyperbaric oxygen treatment (HBOT) since HBOT might enhance progressive cancer growth. However, in an oxygen deficit condition, tumor cells are more progressive and can be metastatic. HBOT increasing in oxygen partial pressure may benefit tumor suppression. In this study, we investigated the effects of HBOT on solid tumors, such as lung cancer. Non-small cell human lung carcinoma A549-cell-transferred severe combined immunodeficiency mice (SCID) mice were selected as an in vivo model to detect the potential mechanism of HBOT in lung tumors. HBOT not only improved tumor hypoxia but also suppressed tumor growth in murine xenograft tumor models. Platelet endothelial cell adhesion molecule (PECAM-1/CD31) was significantly increased after HBOT. Immunostaining of cleaved caspase-3 was demonstrated and apoptotic tumor cells with nuclear debris were aggregated starting on the 14th-day after HBOT. In vitro, HBOT suppressed the growth of A549 cells in a time-dependent manner and immediately downregulated the expression of p53 protein after HBOT in A549 cells. Furthermore, HBOT-reduced p53 protein could be rescued by a proteasome degradation inhibitor, but not an autophagy inhibitor in A549 cells. Our results demonstrated that HBOT improved tissue angiogenesis, tumor hypoxia and increased tumor apoptosis to lung cancer cells in murine xenograft tumor models, through modifying the tumor hypoxic microenvironment. HBOT will merit further cancer therapy as an adjuvant treatment for solid tumors, such as lung cancer

    Audio-video Synchronization with Arbitrary, Non-periodic Video Sources

    Get PDF
    The latency between audio and video streams of a device is usually measured using stock test videos. Although the use of stock test videos eases analysis, the test video differs materially from real-world videos, which tend to be far more diverse in content and encoding schemes, resulting in laborious experimental setup and inaccurate synchronization. This disclosure describes techniques to measure the latency between the audio and video streams of a given device using arbitrary, real-world, audio-visual footage (test video). Characteristic video and audio frames and their differences in timestamps (characteristic durations) are identified within the test video. The test video is played by the device-under-test while being recorded by a high-precision video camera. Characteristic durations of the recorded footage are determined. The differences in characteristic durations between the test and the recorded videos are statistically analyzed to determine the AV asynchrony of the device-under-test

    Electroacupuncture at the Zusanli (ST-36) Acupoint Induces a Hypoglycemic Effect by Stimulating the Cholinergic Nerve in a Rat Model of Streptozotocine-Induced Insulin-Dependent Diabetes Mellitus

    Get PDF
    Animal studies have shown that electroacupuncture (EA) at Zusanli (ST-36) and Zhongwan (CV-12) acupoints reduces plasma glucose concentrations in rats with type II diabetes. However, whether EA reduces plasma glucose levels in type I diabetes is still unknown. In this study, we explore the various non-insulin-dependent pathways involved in EA-induced lowering of plasma glucose. Streptozotocin (STZ) (60 mg kg−1, i.v.) was administered via the femoral vein to induce insulin-dependent diabetes in non-adrenalectomized and in adrenalectomomized rats. EA (15 Hz) was applied for 30 min to bilateral ST-36 acupoints after administration of Atropine (0.1 mg kg−1 i.p.), Eserine (0.01 mg kg−1 i.p.), or Hemicholinium-3 (5 μg kg−1 i.p.) in non-adrenalectomized rats. Rats administered acetylcholine (0.01 mg kg−1 i.v.) did not undergo EA. Adrenalectomized rats underwent EA at bilateral ST-36 acupoints without further treatment. Blood samples were drawn from all rats before and after EA to measure changes in plasma glucose levels. Expression of insulin signaling proteins (IRS1, AKT2) in atropine-exposed rats before and after EA was measured by western blot. Atropine and hemicholinium-3 completely blocked the plasma glucose lowering effects of EA, whereas eserine led to a significant hypoglycemic response. In addition, plasma glucose levels after administration of acetylcholine were significantly lower than the fasting glucose levels. In STZ-adrenalectomized rats, EA did not induce a hypoglycemic response. EA stimulated the expression of IRS1 and AKT2 and atropine treatment blocked the EA-induced expression of those insulin signaling proteins. Taken together, EA at the ST-36 acupoint reduces plasma glucose concentrations by stimulating the cholinergic nerves

    Acute effect of electroacupuncture at the Zusanli acupoints on decreasing insulin resistance as shown by lowering plasma free fatty acid levels in steroid-background male rats

    Get PDF
    <p>Abstract</p> <p>Background</p> <p>Insulin sensitivity has been enhanced by electroacupuncture (EA) in rats, but the EA phenomenon in an insulin resistant state is still unclear. This study reports the use of a large dose of prednisolone to evaluate the effects of EA in a state of insulin resistance.</p> <p>Methods</p> <p>The plasma levels of free fatty acids (FFAs) were estimated in steroid-background rats (SBRs) and compared with those in healthy rats treated with normal saline. In addition, plasma glucose and endogenous insulin levels were assayed to calculate the homeostasis model assessment (HOMA) index. Intravenous glucose tolerance test (IVGTT) was carried out to compare glucose tolerance. The SBRs were randomly divided into EA-treatment and non-EA treatment groups and 15-Hz EA was applied to the bilateral Zusanli acupoints to investigate its effects on insulin resistance. In addition to an insulin challenge test (ICT) and IVGTT, the plasma levels of FFAs were measured and western blot was performed to help determine the effects of EA on the insulin resistant state.</p> <p>Results</p> <p>The plasma levels of FFAs increased markedly in SBRs, the HOMA index was markedly higher, and glucose tolerance was impaired. EA improved glucose tolerance and insulin sensitivity by decreasing the plasma levels of FFAs. Further, the insulin signaling proteins (IRS1) and glucose transporter isoform protein (GLUT4) in skeletal muscle inhibited by prednisolone recovered after EA.</p> <p>Conclusion</p> <p>Insulin resistance was successfully induced by a large dose of prednisolone in male rats. This insulin resistance can be improved by 15 Hz EA at the bilateral Zusanli acupoints, as shown by decreased plasma levels of FFAs.</p
    corecore