Non-Breaking Undular Hydraulic Jump

The discusser performed a large number of experiments on undular hydraulic jumps (CHANSON 1993, 1995a). Most results were reported in CHANSON and MONTES (1995) and CHANSON (1995b, 1995c). The discusser wishes to stress several aspects of undular jump flows and he will show that the work of REINAUER and HAGER did not bring really new information

Nonpolar resistance switching of metal/binary-transition-metal oxides/metal sandwiches: homogeneous/inhomogeneous transition of current distribution

Exotic features of a metal/oxide/metal (MOM) sandwich, which will be the basis for a drastically innovative nonvolatile memory device, is brought to light from a physical point of view. Here the insulator is one of the ubiquitous and classic binary-transition-metal oxides (TMO), such as Fe2O3, NiO, and CoO. The sandwich exhibits a resistance that reversibly switches between two states: one is a highly resistive off-state and the other is a conductive on-state. Several distinct features were universally observed in these binary TMO sandwiches: namely, nonpolar switching, non-volatile threshold switching, and current--voltage duality. From the systematic sample-size dependence of the resistance in on- and off-states, we conclude that the resistance switching is due to the homogeneous/inhomogeneous transition of the current distribution at the interface.Comment: 7 pages, 5 figures, REVTeX4, submitted to Phys. Rev. B (Feb. 23, 2007). If you can't download a PDF file of this manscript, an alternative one can be found on the author's website: http://staff.aist.go.jp/i.inoue

Multiscale modeling and simulation for polymer melt flows between parallel plates

The flow behaviors of polymer melt composed of short chains with ten beads between parallel plates are simulated by using a hybrid method of molecular dynamics and computational fluid dynamics. Three problems are solved: creep motion under a constant shear stress and its recovery motion after removing the stress, pressure-driven flows, and the flows in rapidly oscillating plates. In the creep/recovery problem, the delayed elastic deformation in the creep motion and evident elastic behavior in the recovery motion are demonstrated. The velocity profiles of the melt in pressure-driven flows are quite different from those of Newtonian fluid due to shear thinning. Velocity gradients of the melt become steeper near the plates and flatter at the middle between the plates as the pressure gradient increases and the temperature decreases. In the rapidly oscillating plates, the viscous boundary layer of the melt is much thinner than that of Newtonian fluid due to the shear thinning of the melt. Three different rheological regimes, i.e., the viscous fluid, visco-elastic liquid, and visco-elastic solid regimes, form over the oscillating plate according to the local Deborah numbers. The melt behaves as a viscous fluid in a region for $\omega\tau^R\lesssim 1$, and the crossover between the liquid-like and solid-like regime takes place around $\omega\tau^\alpha\simeq 1$ (where $\omega$ is the angular frequency of the plate and $\tau^R$ and $\tau^\alpha$ are Rouse and $\alpha$ relaxation time, respectively).Comment: 13pages, 12figure

Randomness-driven quantum phase transition in bond-alternating Haldane chain

The effect of bond randomness on the spin-gapped ground state of the spin-1 bond-alternating antiferromagnetic Heisenberg chain is discussed. By using the loop cluster quantum Monte Carlo method, we investigate the stability of topological order in terms of the recently proposed twist order parameter [M. Nakamura and S. Todo: Phys. Rev. Lett. 89 (2002) 077204]. It is observed that the dimer phases as well as the Haldane phase of the spin-1 Heisenberg chain are robust against a weak randomness, though the valence-bond-solid-like topological order in the latter phase is destroyed by introducing a disorder stronger than the critical value.Comment: 4 pages, 5 figures; minor changes; accepted for publication in J. Phys. Soc. Jp

Effect of interleukins response to ECM-induced acquisition of drug resistance in MCF-7 cells

Aim: To examine the effect of various components of extracellular matrix (ECM) on acquisition of drug resistance to taxol and camptothecin by breast carcinoma cell line MCF-7. Methods: Cancer cells were cultured on bovine serum albumin (BSA), vitronectin (VN), fibronectin (FN), collagen type I (COL-I), or Matrigel-coated plates with or without taxol (paclitaxel) or camptothecin treatment. The effect of anticancer drugs on cell growth was accessed by XTT assay, and the alterations of cellular morphology were examined by phase contrast microscopy. Immunofluorescence study was performed using monoclonal anti-b-tubulin antibody. Results: All cell lines showed a significant decrease in cell survival when treated with anticancer drugs without components of ECM, whereas survival rates of Caco-2, MCF-7 and NCI-H292 were significantly increased when cells were cultured on COL-I- and Matrigel-coated dishes after treatment with paclitaxel or camptothecin. MCF-7 cells showed and maintained a colony formation when cultured on the COL-I- and Matrigel-coated dish. Moreover, cytotoxicity (IC50) was decreased by taxol (paclitaxel) or camptothecin treatment during colony formation in MCF-7 cells, suggesting that morphological changes could increase survival of cells treated with anticancer drugs. Thick circumferential bundles of microtubules around the periphery of the cells and chromatin condensation was not observed for MCF-7 cells on COL-I- and Matrigel-coated dishes treated with paclitaxel. To confirm this, spheroid cells were prepared, and we found that cytotoxicity was decreased for these cells, and significantly increased when cells were co-cultured on Matrigel- or COL-I-coated upper wells. The effect of anticancer drugs on cell survival was efficiently inhibited by interleukin-6 (IL-6) and interleukin-8 (IL-8). Conclusions: Present results suggested that not only integrin-ECM interactions but also other factors such as IL-6 and IL-8 secreted by cancer cells, cultured on COL-I and Matrigel dishes, are involved in the acquisition of drug resistance by MCF-7.Цель: изучить влияние различных компонентов внеклеточного матрикса (ECM) на приобретение химиорезистентности к таксолу и камптотецину клетками линии карциномы молочной железы MCF-7. Методы: клетки культивировали на платах, покрытых бычьим сывороточным альбумином (BSA), витронектином (VN), фибронектином (FN), коллагеном I типа (COL-I) или матригелем, без и с добавлением таксола (паклитаксел) или камптотецина. Влияние противоопухолевых препаратов на рост клеток изучали с помощью XTT-теста, изменения клеточной морфологии отмечали в фазовом контрастном микроскопе. Иммунофлуоресцентным методом определяли экспрессию β-тубулина. Результаты: для всех клеточных линий показано существенное снижение выживаемости после культивирования с противоопухолевыми препаратами без компонентов ECM, в то время как уровень выживаемости клеток Caco-2, MCF-7 и NCI-H292 значительно возрос при культивировании с таксолом или камптотецином в чашках, покрытых COL-I и матригелем. Для клеток MCF-7 показано формирование и сохранение колоний при культивировании в чашках с COL-I и матригелем. Более того, цитотоксичность (IC50) таксола и во время колониеобразования клеток MCF-7 была снижена, что позволяет предположить, что морфологические изменения могут влиять на выживаемость клеток при культивировании с химиопрепаратом. Для клеток MCF-7, выращиваемых на чашках с COL-I и матригелем, не отмечали образования плотных периферических узлов микротрубочек и конденсации хроматина. Для подтверждения данного наблюдения проведены опыты с клетками, растущими в виде сфероидов. Показано, что цитотоксичность химиопрепаратов по отношению к этим клеткам снижалась и значительно повышалась при ко-культивировании с матригелем или COL-I в верхних камерах. Снижение выживаемости клеток под действием химиопрепаратов эффективно ингибировалось интерлейкином-6 (IL-6) и интерлейкином-8 (IL-8). Выводы: настоящие исследования показали, что не только интегрин-ECM-взаимодействия, но также и другие факторы, такие как IL-6 и IL-8, секретируемые опухолевыми клетками на чашках с COL-I и матригелем, участвуют в приобретении химиорезистентности опухолевыми клетками MCF-7

Hydrographic Observations During the 2002 IOC Contaminant Baseline Survey in the Western Pacific Ocean

The 2002 IOC Contaminant Baseline Survey in the western Pacific Ocean was the fourth in a series of cruises intended to establish the contemporary concentrations of trace elements and other materials in the major water masses of the ocean and to illuminate the pathways by which materials delivered to the surface ocean are incorporated in the subsurface waters. The expedition occupied 9 vertical profile stations encompassing the subtropical and subarctic gyre of the western North Pacific. In addition, underway surface water samples were collected during transits between the stations. This paper uses the temperature, salinity, nutrient, oxygen, and chlorophyll data to set the hydrographic and biological background for the other papers in this theme

Bond-Dilution-Induced Quantum Phase Transitions in Heisenberg Antiferromagnets

Bond-dilution effects on the ground state of the square-lattice antiferromagnetic Heisenberg model, consisting of coupled bond-alternating chains, are investigated by means of the quantum Monte Carlo simulation. It is found that, when the ground state of the non-diluted system is a non-magnetic state with a finite spin gap, a sufficiently weak bond dilution induces a disordered state with a mid gap in the original spin gap, and under a further stronger bond dilution an antiferromagnetic long-range order emerges. While the site-dilution-induced long-range order is induced by an infinitesimal concentration of dilution, there exists a finite critical concentration in the case of bond dilution. We argue that this essential difference is due to the occurrence of two types of effective interactions between induced magnetic moments in the case of bond dilution, and that the antiferromagnetic long-range-ordered phase does not appear until the magnitudes of the two interactions become comparable.Comment: 7 pages, 13 figure