Improved synthesis of the hypoxia probe 5-deutero-5-fluoro-5-deoxy-azomycin arabinoside (FAZA) as a model process for tritium radiolabeling

Peer reviewedPublisher PD

The variety generated by all the ordinal sums of perfect MV-chains

We present the logic BL_Chang, an axiomatic extension of BL (see P. H\'ajek - Metamathematics of fuzzy logic - 1998, Kluwer) whose corresponding algebras form the smallest variety containing all the ordinal sums of perfect MV-chains. We will analyze this logic and the corresponding algebraic semantics in the propositional and in the first-order case. As we will see, moreover, the variety of BL_Chang-algebras will be strictly connected to the one generated by Chang's MV-algebra (that is, the variety generated by all the perfect MV-algebras): we will also give some new results concerning these last structures and their logic.Comment: This is a revised version of the previous paper: the modifications concern essentially the presentation. The scientific content is substantially unchanged. The major variations are: Definition 2.7 has been improved. Section 3.1 has been made more compact. A new reference, [Bus04], has been added. There is some minor modification in Section 3.

Radial and cylindrical symmetry of solutions to the Cahn-Hilliard equation

The paper is devoted to the classification of entire solutions to the Cahn-Hilliard equation $-\Delta u = u-u^3-\delta$ in $\R^N$, with particular interest in those solutions whose nodal set is either bounded or contained in a cylinder. The aim is to prove either radial or cylindrical symmetry, under suitable hypothesis

Coupled orbit and attitude dynamics of a reconfigurable spacecraft with solar radiation pressure

This work investigates the orbital and attitude dynamics of future reconfigurable multi-panel solar sails able to change their shape during a mission. This can be enabled either by changing the relative position of the individual panels, or by using articulated mechanisms and deployable, retractable and/or inflatable structures. Such a model introduces the concept of modular spacecraft of variable morphology to large gossamer spacecraft. However, this joint concept is complex in nature and requires equations for coupled orbit/attitude dynamics. Therefore, as a starting point, the system is modelled as a rigid-body dumbbell consisting of two tip masses connected by a rigid, massless panel. The system is subjected to a central gravitational force field under consideration of solar radiation pressure forces. Therefore, we assign reflectivity coefficients to the tip masses and a high area-to-mass ratio. An analytical Hamiltonian approach is used to describe the planar motion of the system in Sun-centred Keplerian and non-Keplerian circular orbits. The stability and controllability of the system is enabled through changing the reflectivity coefficients, for example through the use of electro-chromic coating on its surface. The creation of artificial unstable equilibria of the system due to the presence of solar radiation pressure and heteroclinic connections between the equilibria are investigated. We further derive a constraint for the solar radiation pressure forces to maintain the system on a circular Sun-centred orbit. It is planned that the structure is eventually capable of reconfiguring between the equilibria by a minimum actuation effort

Natural selection as coarsening

Analogies between evolutionary dynamics and statistical mechanics, such as Fisher's second-law-like "fundamental theorem of natural selection" and Wright's "fitness landscapes", have had a deep and fruitful influence on the development of evolutionary theory. Here I discuss a new conceptual link between evolution and statistical physics. I argue that natural selection can be viewed as a coarsening phenomenon, similar to the growth of domain size in quenched magnets or to Ostwald ripening in alloys and emulsions. In particular, I show that the most remarkable features of coarsening---scaling and self-similarity---have strict equivalents in evolutionary dynamics. This analogy has three main virtues: it brings a set of well-developed mathematical tools to bear on evolutionary dynamics; it suggests new problems in theoretical evolution; and it provides coarsening physics with a new exactly soluble model.Comment: Submitted to J. Stat. Phys. for special issue on evolutionary dynamic

Magnetohydrodynamic flow and heat transfer around a heated cylinder of arbitrary conductivity

The interaction of the liquid metal with the plasma confinement magnetic field constitutes a challenge for the design of fusion reactor blankets, due to the arise of MHD effects: increased pressure drops, heat transfer suppression, etc. To overcome these issues, a dielectric fluid can be employed as coolant for the breeding zone. A typical configuration involves pipes transverse to the liquid metal flow direction. This numerical study is conducted to assess the influence of pipe conductivity on the MHD flow and heat transfer. The CFD code ANSYS CFX was employed for this purpose. The fluid is assumed to be bounded by rectangular walls with non-uniform thickness and subject to a skewed magnetic field with the main component aligned with the cylinder axis. The simulations were restricted to Re = (20, 40) and M = (10, 50). Three different scenarios for the obstacle were considered: perfectly insulating, finite conductivity and perfectly conducting. The electrical conductivity was found to affect the channel pressure penalty due to the obstacle insertion only for M = 10 and just for the two limiting cases. A general increment of the heat transfer with M was found due to the tendency of the magnetic field to equalize the flow rate between the sub-channels individuated by the pipe. The best results were obtained with the insulating pipe, due to the reduced electromagnetic drag. The generation of counter-rotating vortices close to the lateral duct walls was observed for M=50 and perfectly conducting pipe as a result of the modified currents distribution

Thermodynamic length in open quantum systems

The dissipation generated during a quasistatic thermodynamic process can be characterised by introducing a metric on the space of Gibbs states, in such a way that minimally-dissipating protocols correspond to geodesic trajectories. Here, we show how to generalize this approach to open quantum systems by finding the thermodynamic metric associated to a given Lindblad master equation. The obtained metric can be understood as a perturbation over the background geometry of equilibrium Gibbs states, which is induced by the Kubo-Mori-Bogoliubov (KMB) inner product. We illustrate this construction on two paradigmatic examples: an Ising chain and a two-level system interacting with a bosonic bath with different spectral densities.Comment: 22 pages, 3 figures. v5: minor corrections, accepted in Quantu

On surfaces with p_g=q=2, K^2=5 and Albanese map of degree 3

We construct a connected, irreducible component of the moduli space of minimal surfaces of general type with $p_g=q=2$ and $K^2=5$, which contains both examples given by Chen-Hacon and the first author. This component is generically smooth of dimension 4, and all its points parametrize surfaces whose Albanese map is a generically finite triple cover.Comment: 35 pages, 2 figures. Final version, to appear in the Osaka Journal of Mathematic