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Nuclear structures of short-lived radioisotopes are nowadays investigated in large scale facilities based on in-flight fragmentation or isotope separation online (ISOL) methods. The ISOL technique has been constantly extended at CERN-ISOLDE, where 1.4GeV protons are exploited by physicists to create radioisotopes in thick materials; these exotic nuclei are released and pumped online into an ion source, producing a secondary beam which is further selected in a magnetic mass spectrometer before post-acceleration.

Ten years ago a proposal to inject suitable ISOL beams into the CERN accelerator complex and to store these isotopes in a decay ring with straight sections was proposed for a ”Β-beam facility”; intense sources of pure electron neutrinos - emitted when such isotopes decay - are directed towards massive underground detectors for fundamental studies such as observation of neutrino flavour oscillations and CP violation.

Our paper reports on the experimental production of the anti-neutrino emitter 6He. We use a two-step reaction in which the proton beam interacts with a tungsten neutron spallation source. The emitted neutrons intercept a BeO target to produce ⁹Be(n,a)⁶He reactions. The neutron field was simulated by Monte-Carlo codes such as Fluka and experimentally measured. The large predicted ⁶He production rates were also experimentally verified. Fast 6He diffusion, driven by the selection of a suitable BeO material, could be demonstrated, leading to the highest ⁶He beam rates ever achieved at ISOLDE. These results provide a firm experimental confirmation that the Β-beam will be able to deliver enough anti-neutrino rates using a neutron spallation source similar to ISIS-RAL (UK). This work is now being completed by the experimental validation of the ¹⁸Ne neutrino source design.

Lipid bilayers emerge by self-organization of amphiphilic molecules and are the essential component of membranes of living cells. An important task of them is the selective exchange of substances between the cell and its environment. This becomes particularly interesting for delivering foreign molecules and RNA into the cell. In the classical view of cell biology static structures such as pores and channels formed by specific proteins control the translocation of molecules.

In this work we show that there exists a straightforward mechanism for translocation of polymers through lipid bilayers if the monomers of the chain show a certain balance of hydrophobic and hydrophilic strength. Using the bond fluctuation method with explicit solvent to simulate the self-organized lipid bilayer and the polymer chain we show that the chain is adsorbed by the bilayer at a critical hydrophobicity of the monomers. At this point all monomers have an intermediate degree of hydrophobicity, which is large enough to overcome the insertion barrier of the ordered lipids, but still small enough to avoid trapping in the core of the bilayer. In a narrow range around this critical hydrophobicity the chain can almost freely penetrate through the model membrane whose hydrophobic core becomes energetically transparent here. Our simulations also allow calculate the permeability of the membrane with respect to the solvent. We show that the permeability is strongly increased close to the critical hydrophobicity suggesting that here the perturbation of the membrane patch around the adsorbed chain is highest.

What is the general relativistic version of the Navier-Stokes-Fourier dissipative hydrodynamics? Surprisingly, no satisfactory answer to this question is known today. Eckart's early solution [Eckart, Phys. Rev. (1940) 58, 919], is considered outdated on many grounds: the instability of its equilibrium states, ill-posed initial-value formulation, inconsistency with linear irreversible thermodynamics, etc. Although alternative theories have been proposed recently, none appears to have won the consensus.

This paper reconsiders the foundations of Eckart's theory, focusing on its main peculiarity and simultaneous difficulty: the “inertia of heat” term in the constitutive relation for the heat flux, which couples temperature to acceleration. In particular, it shows that this term arises only if one insists on defining the thermal diffusivity independently of the gravitational field. It is argued that this is not a physically sensible approach, because gravitational time dilation implies that the diffusivity actually varies in space. In a nutshell, where time runs faster, thermal diffusion also runs faster. It is proposed that this is the physical meaning of the “inertia of heat” concept, and that such an effect should be expected in any theory of dissipative hydrodynamics that is consistent with general relativity.