Magnetically controlled ballistic deposition. A model of polydisperse granular packing

The flow and deposition of polydisperse granular materials is simulated through the Magnetic Diffusion Limited Aggregation (MDLA) model. The random walk undergone by an entity in the MDLA model is modified such that the trajectories are ballistic in nature, leading to a magnetically controlled ballistic deposition (MBD) model. This allows to obtain important ingredients about a difficult problem that of the nonequilibrium segregation of polydisperse sandpiles and heterogeneous adsorption of a binary distribution of particles which can interact with each other and with an external field. Our detailed results from many simulations of MBD clusters on a two dimensional triangular lattice above a flat surface in a vertical finite size box for binary systems indicates intriguing variations of the density, ''magnetization'', types of clusters, and fractal dimensions. We derive the field and grain interaction dependent susceptibility and compressibility. We deduce a completely new phase diagram for binary granular piles and discuss its complexity inherent to different grain competition and cluster growth probabilities.Comment: 11 pages, 18 figures, submitted to Physica

Granular Matter: a wonderful world of clusters in far-from-equilibrium systems

In this paper, we recall various features of non equilibrium granular systems. Clusters with specific properties are found depending on the packing density, going from loose (a granular gas) to sintered (though brittle) polycrystalline materials. The phase space available can be quite different. Unexpected features, with respect to standard or expected ones in classical fluids or solids, are observed, - like slow relaxation processes or anomalous electrical and thermoelectrical transport property dependences. The cases of various pile structures and the interplay between classical phase transitions and self-organized criticality for avalanches are also outlined.Comment: 7 figures, 37 refs., to be published in Physica

Exotic magnetism in the alkali sesquoxides Rb4O6 and Cs4O6

Among the various alkali oxides the sesquioxides Rb4O6 and Cs4O6 are of special interest. Electronic structure calculations using the local spin-density approximation predicted that Rb4O6 should be a half-metallic ferromagnet, which was later contradicted when an experimental investigation of the temperature dependent magnetization of Rb4O6 showed a low-temperature magnetic transition and differences between zero-field-cooled (ZFC) and field-cooled (FC) measurements. Such behavior is known from spin glasses and frustrated systems. Rb4O6 and Cs4O6 comprise two different types of dioxygen anions, the hyperoxide and the peroxide anions. The nonmagnetic peroxide anions do not contain unpaired electrons while the hyperoxide anions contain unpaired electrons in antibonding pi*-orbitals. High electron localization (narrow bands) suggests that electronic correlations are of major importance in these open shell p-electron systems. Correlations and charge ordering due to the mixed valency render p-electron-based anionogenic magnetic order possible in the sesquioxides. In this work we present an experimental comparison of Rb4O6 and the related Cs4O6. The crystal structures are verified using powder x-ray diffraction. The mixed valency of both compounds is confirmed using Raman spectroscopy, and time-dependent magnetization experiments indicate that both compounds show magnetic frustration, a feature only previously known from d- and f-electron systems

Exponential and power law distribution of mass clusters in a (magnetic-like) deposition model of elongated grains in 2D piles

A generalized so called magnetically controlled ballistic rain-like deposition (MBD) model of granular piles has been numerically investigated in 2D. The grains are taken to be elongated disks whence characterized by a two-state scalar degree of freedom, called ''nip'', their interaction being described through a Hamiltonian. Results are discussed in order to search for the effect of nip flip (or grain rotation from vertical to horizontal and conversely) probability in building a granular pile. The characteristics of creation of + (or $-$) nip's clusters and clusters of holes (missing nips) are analyzed. Two different cluster-mass regimes have been identified, through the cluster-mass distribution function which can be exponential or have a power law form depending on whether the nip flip (or grain rotation) probability is large or small. Analytical forms of the exponent are empirically found in terms of the Hamiltonian parameters.Comment: submitted to Int.J. Mod. Phys. C; 16 figures; 79 reference

Evaluating the implementation of the WHO Healthy Cities Programme across Germany (1999-2002)

The WHO Healthy Cities Project (1988) is a well-known example of the setting-based approach to health promotion. Developed as a framework for translating the key principles of the Ottawa Charter for Health Promotion (1986) into practice, it is best characterized as a process for successfully encouraging healthy public policy. In 2001, the German Healthy Cities Network (HCN) commissioned a survey of the 52 local Healthy Cities programme Coordinators (HCC) to monitor progress and identify strengths and weaknesses associated with its implementation. Most (90%; 47/52) HCC participated in the survey. Several positive aspects of the Health Cities Programmes (HCP) in Germany were identified: during the first 5 years, it expanded rapidly; project coordinators felt highly engaged, despite limited resources; a combination of traditional and innovative approaches was adopted and applauded; and almost 75% of HCC felt that their efforts had been beneficial. Nonetheless, the following shortcomings were identified: increased resources required; greater clarification of concepts and strategies at the local level; stronger commitment to the Nine-Point Programme of Action; greater integration within the national HCN and the local political administrative system (PAS); better programme documentation and evaluation. In conclusion, the HCN in Germany has expanded and developed since its inception 20 years ago. German HCP will only improve if professionalism and quality of local work are improved, particularly in terms of strengthening their influence on the local PAS and on public policies

Prognostic significance of endogenous adhesion/growth-regulatory lectins in lung cancer

Objective: To determine the expression of endogenous adhesion/growth-regulatory lectins and their binding sites using labeled tissue lectins as well as the binding profile of hyaluronic acid as an approach to define new prognostic markers. Methods: Sections of paraffin-embedded histological material of 481 lungs from lung tumor patients following radical lung excision processed by a routine immunohistochemical method (avidin-biotin labeling, DAB chromogen). Specific antibodies against galectins-1 and - 3 and the heparin-binding lectin were tested. Staining by labeled galectins and hyaluronic acid was similarly visualized by a routine protocol. After semiquantitative assessment of staining, the results were compared with the pT and pN stages and the histological type. Survival was calculated by univariate and multivariate methods. Results: Binding of galectin-1 and its expression tended to increase, whereas the parameters for galectin-3 decreased in advanced pT and pN stages at a statistically significant level. The number of positive cases was considerably smaller among the cases with small cell lung cancer than in the group with non-small-cell lung cancer, among which adenocarcinomas figured prominently with the exception of galectin-1 expression. Kaplan-Meier computations revealed that the survival rate of patients with galectin-3-binding or galectin-1-expressing tumors was significantly poorer than that of the negative cases. In the multivariate calculations of survival lymph node metastases ( p < 0.0001), histological type ( p = 0.003), galectin-3-binding capacity ( p = 0.01), galectin-3 expression ( p = 0.03) and pT status ( p = 0.003) proved to be independent prognostic factors, not correlated with the pN stage. Conclusion: The expression and the capacity to bind the adhesion/growth regulatory galectin-3 is defined as an unfavorable prognostic factor not correlated with the pTN stage. Copyright (C) 2005 S. Karger AG, Basel

Expressive and Instrumental Offending: Reconciling the Paradox of Specialisation and Versatility

Although previous research into specialisation has been dominated by the debate over the existence of specialisation versus versatility, it is suggested that research needs to move beyond the restrictions of this dispute. The current study explores the criminal careers of 200 offenders based on their criminal records, obtained from a police database in the North West of England, aiming to understand the patterns and nature of specialisation by determining the presence of differentiation within their general offending behaviours and examining whether the framework of Expressive and Instrumental offending styles can account for any specialised tendencies that emerge. Fifty-eight offences were subjected to Smallest Space Analysis. Results revealed that a model of criminal differentiation could be identified and that any specialisation is represented in terms of Expressive and Instrumental offending styles

Barkhausen noise emission of AISI 304 stainless steel originating from strain induced martensite by shot peening

This study deals with magnetic Barkhausen noise emission produced by strain-induced martensite generated during shot peening of austenitic AISI 304 stainless steel. The transformation from the paramagnetic to ferromagnetic state and the corresponding birth of the magnetic domain structure are important with respect to irreversible motion of domain walls and the corresponding Barkhausen noise emission. Barkhausen noise is investigated and explained with respect to the residual stress state as well as the micro-structure expressed in terms of the martensite fraction, its crystallite size, preferred orientation, surface topography, and microhardness. The strength of the Barkhausen noise is mainly linked with the number of shot peening cycles, corresponding Almen intensity, and the associated volume fraction of strain-induced martensite as well as the extent of its depth. The role of the residual stress state in the martensite phase is minor. Surface strengthening expressed in terms of the microhardness in the near-surface region is very high for the medium shot peening intensity. A remarkable decrease in the near-surface microhardness as well as the presence of heavily thinned folds indicate over shot peen-ing and surface microcracking in the case of a longer shot peening time and the corre-sponding higher Almen intensity.Web of Science2076274

Transparent dense sodium

Under pressure, metals exhibit increasingly shorter interatomic distances. Intuitively, this response is expected to be accompanied by an increase in the widths of the valence and conduction bands and hence a more pronounced free-electron-like behaviour. But at the densities that can now be achieved experimentally, compression can be so substantial that core electrons overlap. This effect dramatically alters electronic properties from those typically associated with simple free-electron metals such as lithium and sodium, leading in turn to structurally complex phases and superconductivity with a high critical temperature. But the most intriguing prediction - that the seemingly simple metals Li and Na will transform under pressure into insulating states, owing to pairing of alkali atoms - has yet to be experimentally confirmed. Here we report experimental observations of a pressure-induced transformation of Na into an optically transparent phase at 200 GPa (corresponding to 5.0-fold compression). Experimental and computational data identify the new phase as a wide bandgap dielectric with a six-coordinated, highly distorted double-hexagonal close-packed structure. We attribute the emergence of this dense insulating state not to atom pairing, but to p-d hybridizations of valence electrons and their repulsion by core electrons into the lattice interstices. We expect that such insulating states may also form in other elements and compounds when compression is sufficiently strong that atomic cores start to overlap strongly.Comment: Published in Nature 458, 182-185 (2009

Upper critical field, lower critical field and critical current density of FeTe0.60Se0.40 single crystal

The transport and magnetic studies are performed on high quality FeTe0.60Se0.40 single crystals to determine the upper critical fields (Hc2), lower critical field (Hc1) and the Critical current density (Jc). The value of upper critical field Hc2 are very large, whereas the activation energy as determined from the slope of the Arrhenius plots are was found to be lower than that in the FeAs122 superconductor. The lower critical field was determined in ab direction and c direction of the crystal, and was found to have a anisotropy of 'gamma'{=(Hc1//c) / (Hc1//b)} ~ 4. The magnetic isotherms measured up to 12 Tesla shows the presence of fishtail behavior. The critical current densities at 1.8K of the single crystal was found to almost same in both ab and c direction as 1X105 Amp/cm2 in low field regime.Comment: 9 pages, 6 figure