Well structured program equivalence is highly undecidable

We show that strict deterministic propositional dynamic logic with intersection is highly undecidable, solving a problem in the Stanford Encyclopedia of Philosophy. In fact we show something quite a bit stronger. We introduce the construction of program equivalence, which returns the value $\mathsf{T}$ precisely when two given programs are equivalent on halting computations. We show that virtually any variant of propositional dynamic logic has $\Pi_1^1$-hard validity problem if it can express even just the equivalence of well-structured programs with the empty program \texttt{skip}. We also show, in these cases, that the set of propositional statements valid over finite models is not recursively enumerable, so there is not even an axiomatisation for finitely valid propositions.Comment: 8 page

Electrostatic solvation free energies of charged hard spheres using molecular dynamics with density functional theory interactions

Determining the solvation free energies of single ions in water is one of the most fundamental problems in physical chemistry and yet many unresolved questions remain. In particular, the ability to decompose the solvation free energy into simple and intuitive contributions will have important implications for models of electrolyte solution. Here, we provide definitions of the various types of single ion solvation free energies based on different simulation protocols. We calculate solvation free energies of charged hard spheres using density functional theory interaction potentials with molecular dynamics simulation (DFT-MD) and isolate the effects of charge and cavitation, comparing to the Born (linear response) model. We show that using uncorrected Ewald summation leads to unphysical values for the single ion solvation free energy and that charging free energies for cations are approximately linear as a function of charge but that there is a small non-linearity for small anions. The charge hydration asymmetry (CHA) for hard spheres, determined with quantum mechanics, is much larger than for the analogous real ions. This suggests that real ions, particularly anions, are significantly more complex than simple charged hard spheres, a commonly employed representation.Comment: 28 pages, 5 figure

Effects of hemodialysis on circulating adrenomedullin concentrations in patients with end-stage renal disease

To characterize the determinants of circulating levels of adrenomedullin (AM), the plasma levels of this peptide were measured in 58 patients with end-stage renal disease on hemodialysis, Predialysis plasma levels of AM were more than twice as high in patients on hemodialysis as compared to controls. In hemodialysis patients with heart failure (NYHA classes II-IV) or hypertensive HD patients plasma levels of AM were significantly higher than in patients with end-stage renal disease only. Plasma levels of AM were clot altered immediately by hemodialysis but decreased significantly 14-20 h after hemodialysis, AM plasma levels before hemodialysis and 14-20 h after hemodialysis were correlated with the corresponding mean arterial pressure

Real single ion solvation free energies with quantum mechanical simulation

Single ion solvation free energies are one of the most important properties of electrolyte solutions and yet there is ongoing debate about what these values are. Only the values for neutral ion pairs are known. Here, we use DFT interaction potentials with molecular dynamics simulation (DFT-MD) combined with a modified version of the quasi-chemical theory (QCT) to calculate these energies for the lithium and fluoride ions. A method to correct for the error in the DFT functional is developed and very good agreement with the experimental value for the lithium fluoride pair is obtained. Moreover, this method partitions the energies into physically intuitive terms such as surface potential, cavity and charging energies which are amenable to descriptions with reduced models. Our research suggests that lithium's solvation free energy is dominated by the free energetics of a charged hard sphere, whereas fluoride exhibits significant quantum mechanical behavior that cannot be simply described with a reduced model.Comment: 13 pages, 4 figure

Experimental demonstration of composite stimulated Raman adiabatic passage

We experimentally demonstrate composite stimulated Raman adiabatic passage (CSTIRAP), which combines the concepts of composite pulse sequences and adiabatic passage. The technique is applied for population transfer in a rare-earth doped solid. We compare the performance of CSTIRAP with conventional single and repeated STIRAP, either in the resonant or the highly detuned regime. In the latter case, CSTIRAP improves the peak transfer efficiency and robustness, boosting the transfer efficiency substantially compared to repeated STIRAP. We also propose and demonstrate a universal version of CSTIRAP, which shows improved performance compared to the originally proposed composite version. Our findings pave the way towards new STIRAP applications, which require repeated excitation cycles, e.g., for momentum transfer in atom optics, or dynamical decoupling to invert arbitrary superposition states in quantum memories.Comment: 11 pages, 5 figure

Induction of male sterility in wheat and barley by 2-chloroethylphosphonic acid (ethephon)

Emphasis has been directed towards the potential use of ethephon (2-chloroethylphosphonic acid) as a possible gametocide for induction of male sterility. Currently ethephon has been used experimentally as a male gametocide on both wheat and barley. The purpose of this research was to induce male sterility in winter wheat (Triticum aestivum L. em Thell), and winter barley (Hordeum vulgare L.) with foliar applications of ethephon. The field study was conducted at the Plant Science Field Laboratory, Knoxville, Tennessee. Ethephon was foliarly sprayed on Arthur wheat and Volbar barley, at 0.00, 0.10, 0.20, and 0.40 percent active ingredient when the plants were in early, mid-, and late boot stages. The most effective level was 0.40 percent ethephon in early, mid-, and late boot for Arthur wheat, and early, and late boot for Volbar barley. Concentration, stage, and concentration*stage interaction were significant for all variables except for seed weight. No concentration, stage or concentration*stage interaction occurred for seed weight. However there were significant differences among concentrations and stages which directly influenced male sterility. All ethephon treatments resulted in reduced plant heights and lodging. There was no apparent reduction in female fertility as a result of the treatments. The results of this research indicated that ethephon might have possibilities as a rapid and easy means of hybridization in wheat and barley