Search

A quasi-geostrophic model of Southern Hemisphere's wintertime atmospheric circulation with horizontal resolution T21 has been coupled to a global ocean circulation model with a resolution of 2° × 2° and simplified physics. This simplified coupled model reproduces qualitatively some features of the first and the second EOF of atmospheric 833 hPa geopotential height in accordance with NCEP data. The variability patterns of the simplified coupled model have been compared with variability patterns simulated by four complex state-of-the-art coupled CMIP5 models. The first EOF of the simplified model is too zonal and does not reproduce the right position of the centre of action over the Pacific Ocean and its extension to the tropics. The agreement in the second EOF between the simplified and the CMIP5 models is better. The total variance of the simplified model is weaker than the observational variance and those of the CMIP5 models. The transport properties of the Southern Ocean circulation are in qualitative accord with observations. The simplified model exhibits skill in reproducing essential features of decadal and multi-decadal climate variability in the extratropical Southern Hemisphere. Notably, 800 yr long coupled model simulations reveal sea surface temperature fluctuations on the timescale of several decades in the Antarctic Circumpolar Current region.

From a dynamical systems theory perspective, the mechanisms of atmospheric regime behavior in a barotropic model, a pseudobarotropic model, and a baroclinic three-level model, where all of them show quite realistic regimes, are unveiled. Along with this, the role played by multiple equilibria for the emergence of regimes in barotropic models is critically reexamined. In the barotropic model, a sequence of bifurcations is observed, which leads to the merging of coexisting attractors and results in two pronounced regimes corresponding to high- and low-index flow. The pseudobarotropic model is constructed from the three-level model by introducing a strong internal friction between the levels and switching off the interfacial diabatic forcing, and it has essentially the same bifurcation properties and regimes as the truly barotropic model. A continuous metamorphosis between the pseudobarotropic and the original baroclinic three-level model is accomplished by a linear interpolation of parameters and forcing fields between these two models. Both local and global bifurcations occurring during this transition to baroclinicity are analyzed in detail, yielding two main results. First, almost all of the multiple steady states of the pseudobarotropic model owe their existence merely to the fact that the surface friction has generally to be chosen unphysically weak in barotropic models in order to obtain chaotic behavior. Second, the circulation regimes in both the pseudobarotropic model and the baroclinic three-level model are proven to emerge from the unification of multiple attractors, which coexist at intermediate strength of baroclinicity and correspond to low- or high-index flow configurations, respectively.

Dynamical mechanisms of atmospheric regime behavior are investigated in the context of a quasigeostrophic three-level T21 model of the wintertime atmospheric circulation over the Northern Hemisphere. The model, driven by realistic orography and using a thermal forcing determined by a newly developed tuning procedure, is shown to possess a reasonable climatology and to simulate the Arctic Oscillation quite realistically. It exhibits pronounced internally generated interannual and decadal variability and, in particular, circulation regimes that agree fairly well with observed ones. Two known hypotheses about the origin of regime behavior, as it occurs in the model herein are addressed: (i) multiple equilibria and (ii) chaotic itinerancy between attractor ruins. The first hypothesis is falsified at very high probability, while the second is likely to be true.

In an idealized model of northern hemisphere's wintertime atmospheric circulation, it is shown that the Northern Annular Mode arises from an annular pattern on a rotating aqua-planet and is modified to a zonally asymmetric pattern by land–sea contrasts and orography, connected with the localization of transient baroclinic activity. Copyright © 2005 Royal Meteorological Society

The objectives of this study were to determine whether differences in the size and composition of coarse (2.5-10 micro m), fine (< 2.5 microm), and ultrafine (< 0.1 microm) particulate matter (PM) are related to their uptake in macrophages and epithelial cells and their ability to induce oxidative stress. The premise for this study is the increasing awareness that various PM components induce pulmonary inflammation through the generation of oxidative stress. Coarse, fine, and ultrafine particles (UFPs) were collected by ambient particle concentrators in the Los Angeles basin in California and used to study their chemical composition in parallel with assays for generation of reactive oxygen species (ROS) and ability to induce oxidative stress in macrophages and epithelial cells. UFPs were most potent toward inducing cellular heme oxygenase-1 (HO-1) expression and depleting intracellular glutathione. HO-1 expression, a sensitive marker for oxidative stress, is directly correlated with the high organic carbon and polycyclic aromatic hydrocarbon (PAH) content of UFPs. The dithiothreitol (DTT) assay, a quantitative measure of in vitro ROS formation, was correlated with PAH content and HO-1 expression. UFPs also had the highest ROS activity in the DTT assay. Because the small size of UFPs allows better tissue penetration, we used electron microscopy to study subcellular localization. UFPs and, to a lesser extent, fine particles, localize in mitochondria, where they induce major structural damage. This may contribute to oxidative stress. Our studies demonstrate that the increased biological potency of UFPs is related to the content of redox cycling organic chemicals and their ability to damage mitochondria.

BACKGROUND. Caloric restriction (CR) retards aging and diseases in mice, rats, and other animals by unknown mechanisms. A popular hypothesis is that CR acts by opposing age-associated increases in oxidative stress. METHODS. Because influences of CR on antioxidant enzymes in the prostate have not been previously investigated, immunohistologic methods (light and electron microscopy) were used to determine the prostatic localization of catalase (CAT) in rats of diverse ages (3-32 months) fed either normally or subjected to CR from age 16 months. RESULTS. In 20-month-old rats fed either diet, CAT appeared as dense deposits at the apical poles of the epithelium in the lateral lobes, and within the ductular lumens, suggesting that CAT is secreted. Confirmation of both liver peroxisomal and prostatic apical cytoplasmic localization of CAT was provided by electron microscopic immunogold staining. The amount of CAT was reduced at 30 months in normally fed rats but not in those on CR. CONCLUSIONS. CAT appears to be a secretory product of the epithelial cells in the lateral lobes of the rat prostate. Further, CR from late-middle age opposed the age-associated loss of this intracellular enzyme activity.

Immunolocalization studies of hamster kidney development were performed using polyclonal antibodies to antioxidant enzymes, including antibodies to copper, zinc and manganese superoxide dismutases, catalase, glutathione peroxidase and glutathioneS-transferases and their subunits. Antibodies to extracellular matrix proteins were also studied to determine the temporal sequence between expression of immunoreactive protein for basement membrane proteins, which serve as markers of embryonic induction of nephron development, and antioxidant enzyme expression in kidney development. Immunoreactive proteins for antioxidant enzymes were not detectable in the developing kidney until after extracellular matrix proteins had been deposited. However, immunoreactive proteins for the antioxidant enzymes copper, zinc and manganese superoxide dismutases, catalase, and α class glutathioneS-transferase Ya subunit were detected in renal tubules before birth. μ class glutathioneS-transferase subunits Yb1 and Yb2 stained transitional epithelium at high levels before birth. Our results indicate: (1) each type of kidney cell has a unique antioxidant enzyme profile, (2) antioxidant enzymes are expressed in different types of cell at different times during development, but antioxidant enzyme immunoreactive protein was not present until after immunoreactive proteins for extracellular matrix molecules were detected, and (3) certain antioxidant enzymes are present before birth, indicating that high oxygen tension present at birth is not crucial for induction of immunoreactive protein.

The design and implementation of a simplified coupled atmosphere-ocean model over mid and high Southern Hemisphere latitudes are described. The development of the model is motivated by the clear indications of important low-frequency variability of extratropical origin in atmosphere-only models and the crucial role of atmosphere-ocean interaction in altering and shaping the climate variability on decadal and multidecadal time-scales. The basic model consists of an idealized quasi-geostrophic model of Southern Hemisphere's wintertime atmospheric circulation coupled to a general ocean circulation model with simplified physics. Model spin-up is described, some basic descriptors of the model climatology are discussed, and it is argued that the model exhibits skill in reproducing essential features of decadal and multi-decadal climate variability in the extratropical Southern Hemisphere. Notably, 1000 yr long coupled model simulations reveal sea surface temperature fluctuations on the timescale of several decades in the Antarctic Circumpolar Current region.

The ASDEX Upgrade programme is directed towards physics input to critical elements of the ITER design and the preparation of ITER operation, as well as addressing physics issues for a future DEMO design. After the finalization of the tungsten coating of the plasma facing components, the re-availability of all flywheel-generators allowed high-power operation with up to 20 MW heating power at I p up to 1.2 MA. Implementation of alternative ECRH schemes (140 GHz O2- and X3-mode) facilitated central heating above n e = 1.2 × 1020 m−3 and low q 95 operation at B t = 1.8 T. Central O2-mode heating was successfully used in high P/R discharges with 20 MW total heating power and divertor load control with nitrogen seeding. Improved energy confinement is obtained with nitrogen seeding both for type-I and type-III ELMy conditions. The main contributor is increased plasma temperature, no significant changes in the density profile have been observed. This behaviour may be explained by higher pedestal temperatures caused by ion dilution in combination with a pressure limited pedestal and hollow nitrogen profiles. Core particle transport simulations with gyrokinetic calculations have been benchmarked by dedicated discharges using variations of the ECRH deposition location. The reaction of normalized electron density gradients to variations of temperature gradients and the T e/T i ratio could be well reproduced. Doppler reflectometry studies at the L–H transition allowed the disentanglement of the interplay between the oscillatory geodesic acoustic modes, turbulent fluctuations and the mean equilibrium E × B flow in the edge negative E r well region just inside the separatrix. Improved pedestal diagnostics revealed also a refined picture of the pedestal transport in the fully developed H-mode type-I ELM cycle. Impurity ion transport turned out to be neoclassical in between ELMs. Electron and energy transport remain anomalous, but exhibit different recovery time scales after an ELM. After recovery of the pre-ELM profiles, strong fluctuations develop in the gradients of n e and T e. The occurrence of the next ELM cannot be explained by the local current diffusion time scale, since this turns out to be too short. Fast ion losses induced by shear Alfvén eigenmodes have been investigated by time-resolved energy and pitch angle measurements. This allowed the separation of the convective and diffusive loss mechanisms.

This addendum applies to papers authored by contributors from the Axially Symmetric Divertor Experiment (ASDEX) Upgrade Team published in Review of Scientific Instruments. This addendum provides the full list of ASDEX Upgrade Team contributors and their affiliations.

Resistive walls, located close to the plasma boundary, reduce the growth rates of external kink modes to resistive time scales. For such slowly growing resistive wall modes, the stabilization by an active feedback system becomes feasible. The fully three-dimensional stability code STARWALL, and the feedback optimization code OPTIM have been developed [P. Merkel and M. Sempf, 21st IAEA Fusion Energy Conference 2006, Chengdu, China (International Atomic Energy Agency, Vienna, 2006, paper TH/P3-8] to compute the growth rates of resistive wall modes in the presence of nonaxisymmetric, multiply connected wall structures and to model the active feedback stabilization of these modes. In order to demonstrate the capabilities of the codes and to study the effect of the toroidal mode coupling caused by multiply connected wall structures, the codes are applied to test equilibria using the resistive wall structures currently under debate for ITER [M. Shimada et al., Nucl. Fusion 47, S1 (2007)] and ASDEX Upgrade [W. K...

This paper deals with three-dimensional effects in tokamaks that can be approximated by slowly varying 3D equilibria so that their theoretical description and corresponding code developments can benefit from stellarator research. We investigate the effect of magnetic field ripple and magnetic islands on fast particle orbits and find a strong synergistic effect. The coupling of the plasma perturbation to realistic tokamak wall structures introduces 3D elements into the treatment of resistive wall modes (RWMs). We have developed and successfully benchmarked an RWM code allowing for 3D plasma equilibria and wall geometries. We show that for realistic wall structures the 3D effects remove the degeneracy of ±n modes and can give rise to significant coupling of modes with different toroidal mode numbers n. Kinetic damping of RWMs by plasma rotation is investigated in the low rotation regime relevant for ITER and DEMO. It is found that the inclusion of drift wave physics results in an increased damping for plasma rotation velocities in the range of the diamagnetic frequency due to the resonant excitation of electrostatic plasma waves.

Nanomaterial properties differ from those bulk materials of the same composition, allowing them to execute novel activities. A possible downside of these capabilities is harmful interactions with biological systems, with the potential to generate toxicity. An approach to assess the safety of nanomaterials is urgently required. We compared the cellular effects of ambient ultrafine particles with manufactured titanium dioxide (TiO2), carbon black, fullerol, and polystyrene (PS) nanoparticles (NPs). The study was conducted in a phagocytic cell line (RAW 264.7) that is representative of a lung target for NPs. Physicochemical characterization of the NPs showed a dramatic change in their state of aggregation, dispersibility, and charge during transfer from a buffered aqueous solution to cell culture medium. Particles differed with respect to cellular uptake, subcellular localization, and ability to catalyze the production of reactive oxygen species (ROS) under biotic and abiotic conditions. Spontaneous ROS production was compared by using an ROS quencher (furfuryl alcohol) as well as an NADPH peroxidase bioelectrode platform. Among the particles tested, ambient ultrafine particles (UFPs) and cationic PS nanospheres were capable of inducing cellular ROS production, GSH depletion, and toxic oxidative stress. This toxicity involves mitochondrial injury through increased calcium uptake and structural organellar damage. Although active under abiotic conditions, TiO2 and fullerol did not induce toxic oxidative stress. While increased TNF-alpha production could be seen to accompany UFP-induced oxidant injury, cationic PS nanospheres induced mitochondrial damage and cell death without inflammation. In summary, we demonstrate that ROS generation and oxidative stress are a valid test paradigm to compare NP toxicity. Although not all materials have electronic configurations or surface properties to allow spontaneous ROS generation, particle interactions with cellular components are capable of generating oxidative stress.

[1] This paper presents combined winter climate regimes for the 1766–2000 period over the North Atlantic/European sector. We expand previous studies on recurrent regimes by combining spatially high-resolved independent reconstructions of the 500 hPa geopotential height, land surface air temperature, and precipitation fields. Nonlinear Principal Component Analysis is applied to the data in order to account for the underlying nonlinear dynamics of climate regimes. Three recurrent winter climate regimes are detected. One regime resembles in its pressure, temperature, and precipitation pattern the positive phase of the North Atlantic Oscillation, whereas the other two regimes are European blocking situations.

Inhaled diesel exhaust particles (DEP) exert proinflammatory effects in the respiratory tract. This effect is related to the particle content of redox cycling chemicals and is involved in the adjuvant effects of DEP in atopic sensitization. We demonstrate that organic chemicals extracted from DEP induce oxidative stress in normal and transformed bronchial epithelial cells, leading to the expression of heme oxygenase 1, activation of the c-Jun N-terminal kinase cascade, IL-8 production, as well as induction of cytotoxicity. Among these effects, heme oxygenase 1 expression is the most sensitive marker for oxidative stress, while c-Jun N-terminal kinase activation and induction of apoptosis-necrosis require incremental amounts of the organic chemicals and increased levels of oxidative stress. While a macrophage cell line (THP-1) responded in similar fashion, epithelial cells produced more superoxide radicals and were more susceptible to cytotoxic effects than macrophages. Cytotoxicity is the result of mitochondrial damage, which manifests as ultramicroscopic changes in organelle morphology, a decrease in the mitochondrial membrane potential, superoxide production, and ATP depletion. Epithelial cells also differ from macrophages in not being protected by a thiol antioxidant, N-acetylcysteine, which effectively protects macrophages against cytotoxic DEP chemicals. These findings show that epithelial cells exhibit a hierarchical oxidative stress response that differs from that of macrophages by more rapid transition from cytoprotective to cytotoxic responses. Moreover, epithelial cells are not able to convert N-acetylcysteine to cytoprotective glutathione.

Caloric restriction (CR) retards aging and diseases in mice, rats, and other animals by unknown mechanisms. A popular hypothesis is that CR acts by opposing age-associated increases in oxidative stress.Because influences of CR on antioxidant enzymes in the prostate have not been previously investigated, immunohistologic methods (light and electron microscopy) were used to determine the prostatic localization of catalase (CAT) in rats of diverse ages (3-32 months) fed either normally or subjected to CR from age 16 months.In 20-month-old rats fed either diet, CAT appeared as dense deposits at the apical poles of the epithelium in the lateral lobes, and within the ductular lumens, suggesting that CAT is secreted. Confirmation of both liver peroxisomal and prostatic apical cytoplasmic localization of CAT was provided by electron microscopic immunogold staining. The amount of CAT was reduced at 30 months in normally fed rats but not in those on CR.CAT appears to be a secretory product of the epithelial cells in the lateral lobes of the rat prostate. Further, CR from late-middle age opposed the age-associated loss of this intracellular enzyme activity.

Immunogold studies of normal human kidney and common human kidney cancers were performed using polyclonal antibodies to antioxidant enzymes, including antibodies to copper, zinc and manganese superoxide dismutases, catalase, glutathione peroxidase, and glutathione S-transferases and their subunits. Normal tissue adjacent to human renal tumors had the same antioxidant enzyme immunoreactive protein profiles as normal human kidney, thus establishing that the presence of tumor does not alter the levels of antioxidant enzyme immunoreactive proteins in adjacent kidney tissue. Levels of immunoreactive protein for antioxidant enzymes were determined in four common types of malignant renal cancer. In general, tumors had low levels of antioxidant enzymes; however, certain histologic types of renal tumors had high levels of immunoreactive protein for glutathione S-transferase subunits, which could affect their susceptibility to chemotherapy. Studies of transitional carcinoma of the renal pelvis were especially informative since it was possible to compare levels of antioxidant enzyme immunoreactive protein with adjacent normal transitional epithelium; the majority of antibodies resulted in lower levels of immunoreactive protein in transitional cell carcinoma than in adjacent normal transitional epithelium. Our results are discussed in relation to the response of renal tumors to therapy.

Immunolocalization studies of hamster kidney development were performed using polyclonal antibodies to antioxidant enzymes, including antibodies to copper, zinc and manganese superoxide dismutases, catalase, glutathione peroxidase and glutathione S-transferases and their subunits. Antibodies to extracellular matrix proteins were also studied to determine the temporal sequence between expression of immunoreactive protein for basement membrane proteins, which serve as markers of embryonic induction of nephron development, and antioxidant enzyme expression in kidney development. Immunoreactive proteins for antioxidant enzymes were not detectable in the developing kidney until after extracellular matrix proteins had been deposited. However, immunoreactive proteins for the antioxidant enzymes copper, zinc and manganese superoxide dismutases, catalase, and alpha class glutathione S-transferase Ya subunit were detected in renal tubules before birth. mu class glutathione S-transferase subunits Yb1 and Yb2 stained transitional epithelium at high levels before birth. Our results indicate: (1) each type of kidney cell has a unique antioxidant enzyme profile, (2) antioxidant enzymes are expressed in different types of cell at different times during development, but antioxidant enzyme immunoreactive protein was not present until after immunoreactive proteins for extracellular matrix molecules were detected, and (3) certain antioxidant enzymes are present before birth, indicating that high oxygen tension present at birth is not crucial for induction of immunoreactive protein.

Immunoperoxidase and immunogold techniques were used to localize the following antioxidant enzyme systems in the adult hamster kidney at the light and ultrastructural levels: superoxide dismutases, catalases, peroxidases and glutathione S-transferases. Each cell type in the kidney showed specific patterns of labelling of these enzymes. For example, proximal and distal tubular and transitional epithelial cells showed significant staining for all of these enzymes, while glomerular cells and cells of the thin loop of Henle did not show significant staining at the light microscope level. In addition, high levels of glutathione peroxidase were found in smooth muscle cells of renal arteries. At the ultrastructural level, each enzyme was found in a specific subcellular location. Manganese superoxide dismutase was found in mitochondria, catalase was localized in peroxisomes, while copper, zinc superoxide dismutase and glutathione S-transferase (liver and placental forms) were found in both the nucleus and cytoplasm. Glutathione peroxidase was found to have a broad intracellular distribution, with localization in mitochondria, peroxisomes, nucleus, and cytoplasm. Microvilli of tubular cells were labelled by antibodies to catalase, copper, zinc superoxide dismutase, glutathione peroxidase, and glutathione S-transferases. Cell types that were negative by light microscopy immunoperoxidase studies showed definite labelling with immunogold post-embedding ultrastructural techniques (glomerular cells and cells of the loop of Henle), demonstrating the greater sensitivity of the latter technique. These observations demonstrate that there are large variations in the levels of antioxidant enzymes in different cell types, and that even within a distinct cell type, the levels of these enzymes vary in different subcellular locations. Our results demonstrate for the first time the overall antioxidant enzyme status of individual kidney cell types, thereby explaining why different cell types have differing susceptibilities to oxidant stress. Possible physiological and pathological consequences of these findings are discussed.

Analysis of activities of the antioxidant enzyme manganese superoxide dismutase in human renal cell carcinomas often showed greatly altered enzyme levels (either elevated or depressed) compared to the cell of origin, the kidney proximal tubule. In order to better understand the variability observed, immunogold studies were performed on human renal cell carcinomas using a polyclonal antibody to human kidney manganese superoxide dismutase. For comparison, studies were also performed using antibodies to other antioxidant enzymes. For histologic studies, renal cell carcinomas were subclassified on the basis of light microscopy and ultrastructural analysis into clear cell, granular cell, or mixed clear and granular cell variants. In all three types of tumor, immunogold studies showed little staining using antibodies to copper, zinc superoxide dismutase or glutathione-dependent enzymes. However, intensity of labeling for manganese superoxide dismutase and catalase depended on the cell type(s) in the tumor. Clear cell variants demonstrated trace staining for manganese superoxide dismutase and catalase, while granular cell variants exhibited heavy staining for both of these enzymes. Mixed types of tumors showed clear cells with trace staining for all antioxidant enzymes examined, while granular cells again showed intense labeling for manganese superoxide dismutase and catalase. Using normal kidney proximal tubule as a comparison, immunogold ultrastructural analysis using antibody to manganese superoxide dismutase demonstrated infrequent small lightly labeled mitochondria in clear cell variants, while granular cell variants exhibited numerous medium-sized heavily labeled mitochondria. These data suggest that: 1) the variability in activity values for manganese superoxide dismutase may be due to heterogeneity of cell types in these tumors and 2) manganese superoxide dismutase immunoreactive protein was elevated in granular cells both because of an increase in number of mitochondria and because the labeling density in mitochondria was increased compared to mitochondria in clear cell types or in normal proximal tubular cells.