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To investigate the effects of the middle atmosphere on climate, the World Climate Research Programme is supporting the project 'Stratospheric Processes and their Role in Climate' (SPARC). A central theme of SPARC, to examine model simulations of the coupled troposphere-middle atmosphere system, is being performed through the initiative called GRIPS (GCM-Reality Intercomparison Project for SPARC). In this paper, an overview of the objectives of GRIPS is given. Initial activities include an assessment of the performance of middle atmosphere climate models, and preliminary results from this evaluation are presented here. It is shown that although all 13 models evaluated represent most major features of the mean atmospheric state, there are deficiencies in the magnitude and location of the features, which cannot easily be traced to the formulation (resolution or the parameterizations included) of the models. Most models show a cold bias in all locations, apart from the tropical tropopause region where they can be either too warm or too cold. The strengths and locations of the major jets are often misrepresented in the models. Looking at three-dimensional fields reveals, for some models, more severe deficiencies in the magnitude and positioning of the dominant structures (such as the Aleutian high in the stratosphere), although undersampling might explain some of these differences from observations. All the models have shortcomings in their simulations of the present-day climate, which might limit the accuracy of predictions of the climate response to ozone change and other anomalous forcing.

The dynamics of the square wheel is re-evaluated. It is shown that the minimum coefficient of static friction required for pure rolling decreases from 1 for very slow motion to only 0.105 at the optimum kinetic energy, then increases again for faster motion. The kinetic energy and the equations of motion are derived considering translation of the center of mass and rotation about it in an inertial coordinate system attached to the roadbed and also for rotation about the point of contact. The fact that the instantaneous axis of rotation is accelerating is emphasized and its consequences are discussed.

The realism of extratropical cyclones, fronts, jet streams, and the tropopause in the Goddard Earth Observing System (GEOS) general circulation model (GCM), implemented in assimilation and simulation modes, is evaluated from climatological and case-study perspectives using the GEOS-1 reanalysis climatology and applicable conceptual models as benchmarks for comparison. The latitude-longitude grid spacing of the datasets derived from the GEOS GCM ranges from 2 [degrees] x 2.5 [degrees] to 0.5 [degrees] x 0.5 [degrees]. Frontal systems in the higher-resolution datasets are characterized by horizontal potential temperature gradients that are narrower in scale and larger in magnitude than their lower-resolution counterparts, and various structural features in the Shapiro-Keyser cyclone model are replicated with reasonable fidelity at 1 [degrees] x 1 [degrees] resolution. The remainder of the evaluation focuses on a 3-month Northern Hemisphere winter simulation of the GEOS GCM at 1 [degrees] x 1 [degrees] resolution. The simulation realistically reproduces various large-scale circulation features related to the North Pacific and Atlantic jet streams when compared with the GEOS-1 reanalysis climatology, and conforms closely to a conceptualization of the zonally averaged troposphere and stratosphere proposed originally by Napier Shaw and revised by Hoskins. An extratropical cyclone that developed over the North Atlantic Ocean in the simulation features surface and tropopause evolutions corresponding to the Norwegian cyclone model and to the LC2 life cycle proposed by Thorncroft et al., respectively. These evolutions are related to the position of the developing cyclone with respect to upper-level jets identified in the time-mean and instantaneous flow fields. This article concludes with the enumeration of several research opportunities that may be addressed through the use of state-of-the-art GCMs possessing sufficient resolution to represent mesoscale phenomena and processes explicitly.

The ball milling-induced reduction of MoS2 by Al has been investigated. Although this is a highly exothermic reaction that, based on its thermodynamic properties, should progress as a self-sustaining process, ignition could not be achieved by ball milling. In order to identify the reason, XRD, particle size distribution, SEM, and DTA measurements were carried out on a series of samples milled for different durations. It was found that the largest composite agglomerates broke up due to the presence of a fine dispersion of MoS2 particles. SEM also revealed that the grains are packed rather loosely within the agglomerates. These results indicate that a self-sustaining process can take place only if large and well-compacted composite particles are present. [ABSTRACT FROM AUTHOR]

The reaction between iron and sulfur powders induced by high-energy ball milling was studied as a function of milling time and the composition of starting powders Fe(1 − x) + S(1 + x), where x = −0.03, 0, 0.03, 0.05, 0.10. The reaction products were studied by using the Mössbauer spectra and X-ray diffraction analysis. The analyzed process is self-sustaining and runs for a period of time of 2–5 hours of milling. The iron powder used in this case was characterized by a particle size of 1600 mesh. The Mössbauer spectra obtained at room temperature after 2 hours of milling revealed partial sulfiding missed in the course of X-ray diffraction analysis. In all other samples, we observed a sextet (for an internal magnetic field of 21 MA/m) and a doublet (with insignificant deviations from the corresponding parameters for FeS2). This confirms the results of X-ray phase diffraction analysis according to which FeS is the sole significant phase. [ABSTRACT FROM AUTHOR]

Recently. species specific monoclonal antibodies, directed against the interleukin-2 (IL-2) receptor of murine, rat and human origin, have been produced. In this study we demonstrate with immunohistological methods that cells reacting with these antibodies are present in normal primary and secondary lymphatic organs. The cells are exclusively localized in T cell-dependent areas, and their number increased as a result of immunization. [ABSTRACT FROM AUTHOR]

The proportion and anatomical localization in murine thymus of T cell subpopulations, including those which are defined by the monoclonal anti-interleukin 2 (anti-IL-2) receptor antibody AMT-13, were studied by flow cytofluometry and by immunohistochemical methods, both in irradiated and in normal mice. As a consequence of irradiation the proportion of AMT-13 positive cells and that of Lyt-1 positive cells were markedly enhanced, while the proportion of Lyt-2 positive cells was reduced. The vast majority of the AMT-13 positive cells both in normal and in irradiated thymi were located in the subcapsular area of the thymic cortex, whereas the irradiation resistant Lyt-1 positive cells were located in the medulla. These findings arc compatible with the view that, similar to the developing thymus in the mouse embryo, in the regenerating adult thymus. AMT-13+ cells include the activated pro-thymocytes that repopulate the irradiated thymus. [ABSTRACT FROM AUTHOR]

Monoclonal antibodies anti-Ly 1. anti-Ly 2 and GK1.5 were applied to determine phenotypes of T cells within granulomas formed as a result of infection of mice with the facultative intraccllular bacterium Listeria monocytogenes. Early in granuloma formation, equal numbers of Ly 1+ , Ly 2+ and L3T4+ cells were found, T cells of different phenotypes being evenly distributed over the lesions. In mature granulomas, numbers of Ly 1+ and L3T4+ cells about doubled as compared to incipient granulomas, Ly 2+ cells, however, remained constant. Whereas Ly 1+ and L3T4+ cells within mature granulomas still were evenly distributed, Ly 2+ cells were predominantly Iocalized in the periphery of the lesions. The data indicate that both, specific Ly 2+ and L3T4+ T cells, display characteristic dynamics within granulomas: Ly 2+ T cells which most likely mature from Ly 1+2+ T cells over time locate to the periphery. Concomitantly. L3T4+ T cells are enriched maintaining their distribution all over the lesions. [ABSTRACT FROM AUTHOR]

Abstract: The preparation of nanosized antimony (grain size 19nm) by high-energy milling of antimony sulphide Sb2S3 with elemental Fe as reducing element is reported. The mechanochemical reduction was performed in a planetary ball mill for 10–180min. The process is rather straightforward with elemental antimony and iron sulphide (pyrrhotite-4H) being the only solid-state products. The process kinetics as described by X-ray diffraction (XRD) and vibrating sample magnetometer (VSM) magnetometry shows that most of the reduction is complete after 60min of milling. [Copyright &y& Elsevier]