Short versus long range interactions and the size of two-body weakly bound objects

Very weakly bound systems may manifest intriguing "universal" properties, independent of the specific interaction which keeps the system bound. An interesting example is given by relations between the size of the system and the separation energy, or scaling laws. So far, scaling laws have been investigated for short-range and long-range (repulsive) potentials. We report here on scaling laws for weakly bound two-body systems valid for a larger class of potentials, i.e. short-range potentials having a repulsive core and long-range attractive potentials. We emphasize analogies and differences between the short- and the long-range case. In particular, we show that the emergence of halos is a threshold phenomenon which can arise when the system is bound not only by short-range interactions but also by long-range ones, and this for any value of the orbital angular momentum $\ell$. These results enlarge the image of halo systems we are accustomed to.Comment: 6 pages, 1 figure. To be published in the Proceedings of the Workshop "Hirschegg 2003: Nuclear Structure and Dynamics at the Limits", Hirschegg, January 12 - 18, 200

Universal single level implicit algorithm for gasdynamics

A single level effectively explicit implicit algorithm for gasdynamics is presented. The method meets all the requirements for unconditionally stable global iteration over flows with mixed supersonic and supersonic zones including blunt body flow and boundary layer flows with strong interaction and streamwise separation. For hyperbolic (supersonic flow) regions the method is automatically equivalent to contemporary space marching methods. For elliptic (subsonic flow) regions, rapid convergence is facilitated by alternating direction solution sweeps which bring both sets of eigenvectors and the influence of both boundaries of a coordinate line equally into play. Point by point updating of the data with local iteration on the solution procedure at each spatial step as the sweeps progress not only renders the method single level in storage but, also, improves nonlinear accuracy to accelerate convergence by an order of magnitude over related two level linearized implicit methods. The method derives robust stability from the combination of an eigenvector split upwind difference method (CSCM) with diagonally dominant ADI(DDADI) approximate factorization and computed characteristic boundary approximations

Description of Heavy Quark Systems by means of Energy Dependent Potentials

We apply, for the first time, an energy dependent Schrodinger equation to describe static properties of heavy quark systems, i.e. charmonium and bottonium. We show that a good description of the eigenstates and reasonable values for the widths can be obtained. Values of the radii and of the density at the origin are also given. We compare the results to those deduced with a Schrodinger equation implemented with potentials used so far. We note that the energy dependence of the confining potential provides a natural mechanism for the saturation of the spectra. Our results introduce a new class of potentials for the description of heavy quark systems.Comment: 3 page

The development of an advanced system to cool a man in a pressure suit

Conductive cooling system for cooling man in pressurized space sui

Urban land conflict in the Global South: Towards an analytical framework

In cities of the Global South, access to land is a pressing concern. Typically neither states nor markets provide suitable land for all users, especially low-income households. In the context of urban growth and inequality, acute competition for land and the regulatory failures of states often result in conflict, which is sometimes violent, affecting urban authorities and residents. Conflicts are often mentioned in analyses of urban land, but rarely examined in depth. This paper develops a framework for land conflict analysis, drawing on relevant literature and the papers in this special issue. In order to explore the drivers, dynamics and outcomes of urban land conflicts, diverse disciplinary perspectives are discussed, including environmental security, political ecology, legal anthropology, land governance, conflict analysis and management, and urban conflict and violence. The papers focus on conflicts in the peri-urban areas of Xalapa, Mexico, and Juba, South Sudan, and during informal settlement upgrading in eThekwini (Durban), South Africa, and Nairobi. A second paper on South Africa examines how current tenure law reflects the characteristics and outcomes of previous conflicts. We suggest that an analytical framework needs, first, to consider definitional categories, including the material and emotional dimensions of access to land, conflict and violence, and tenure. Second, it needs to identify and examine the interests and behaviour of the many actors involved in urban land conflicts. And third, it needs to analyse the interactions and relationships between those involved at different levels, from the individual/household, through the local to the citywide, national and international

Termination of the solar wind in the hot, partially ionized interstellar medium

Theoretical foundations for understanding the problem of the termination of the solar wind are reexamined in the light of most recent findings concerning the states of the solar wind and the local interstellar medium. The investigation suggests that a simple extention of Parker's (1961) analytical model provides a useful approximate description of the combined solar wind, interstellar wind plasma flowfield under conditions presently thought to occur. A linear perturbation solution exhibiting both the effects of photoionization and charge exchange is obtained for the supersonic solar wind. A numerical algorithm is described for computing moments of the non-equilibrium hydrogen distribution function and associated source terms for the MHD equations. Computed using the algorithm in conjunction with the extended Parker solution to approximate the plasma flowfield, profiles of hydrogen number density are given in the solar wind along the upstream and downstream axes of flow with respect to the direction of the interstellar wind. Predictions of solar Lyman-alpha backscatter intensities to be observed at 1 a.u. have been computed, in turn, from a set of such hydrogen number density profiles varied over assumed conditions of the interstellar wind

Development of an internal restraint system for an integrated restraint-pressure suit system Report, 7 Jun. 1965 - 28 Jun. 1966

Internal restraint system, composed of liquid filled garment and separate auxiliary system, for integrated restraint pressure suit for acceleration protection and thermal transpor