Thermoelastic properties of ULE® titanium silicate glass

The elastic moduli, and their temperature and pressure derivatives, for ULE titanium silicate glass, have been measured by the ultrasonic pulse superposition technique. From the extrapolated 0 K values of the elastic moduli and their pressure derivatives, the elastic 0 K Debye temperature and Grüneisen constant have been evaluated, and compared with the thermally measured values. The same anomalies in the dynamic propeties as found in other glasses, i.e. positive temperature and negative pressure derivatives, are also found for ULE glass. The correlation between the changes in the bulk modulus and additive in silica-rich glasses is discussed.     

The linkage between reversible Friedel–Crafts acyl rearrangements and the Scholl reaction

Structural Chemistry - Friedel–Crafts acyl rearrangements in PPA (at 80–240 °C) and Scholl reactions in AlCl3/NaCl (at 140–220 °C) of...     

Hidden Markov model likelihoods and their derivatives behave like i.i.d. ones

We consider the log-likelihood function of hidden Markov models, its derivatives and expectations of these (such as different information functions). We give explicit expressions for these functions and bound them as the size of the chain increases. We apply our bounds to obtain partial second order asymptotics and some qualitative properties of a special model as well as to extend some results of [19].     

Deep-inelastic electroproduction of neutrons in the proton fragmentation region

Experiments at HERA looking for deep-inelastic electroproduction of neutrons in the proton fragmentation region are in progress. They are aimed to measure the pion structure function at small Bjorken x. The important condition for such a study is to establish under what kinematical conditions the dominance of the pion-pole graph in the process is guaranteed. We analyse other sources of the leading neutron, in order to figure out the kinematical region where the one-pion exchange dominates.     

Pentaquarks in chiral soliton models

The spectra of pentaquarks, some of them observed recently, are discussed within the topological soliton model and compared with the simplified quark picture. The results obtained within the chiral soliton model depend to some extent on the quantization scheme: rigid rotator, soft rotator, or bound state model. The similarity of the spectra of baryon resonances obtained within the quark model and the chiral soliton model is pointed out, although certain differences take place as well, which require careful interpretation. In particular, considerable variation of the strange antiquark mass in different SU(3) multiplets of pentaquarks is required to fit their spectra obtained from chiral solitons. Certain difference in the masses of “good” and “bad” diquarks is required as well, in qualitative agreement with previously made estimates. The partners of exotic states with different values of spin which belong to higher SU(3) multiplets have energy considerably higher than the states with the lowest spin, and this could be a point where the difference from simple quark models is striking. The antiflavor excitation energies for multibaryons are estimated as well, and the binding energies of gJ-hypernuclei and anticharm (antibeauty) hypernuclei are presented for several baryon numbers. Some deficiencies are pointed out in the arguments in the literature against the validity of the chiral soliton approach and/or the SU(3) quantization models. Based partly on the talks presented at the International Seminar on High Energy Physics Quarks-2004, Pushkinogorie, Russia, May 24–30, 2004; International Workshop on Quantum Field Theory and High Energy Physics QFTHEP-04, Saint-Petersburg, Russia, June 17–23, 2004, and Symposium of London Mathematical Society “Topological Solitons and their Applications,” Durham, UK, August 2–12, 2004. A slightly reduced version of this paper is available as E-print HEP-PH/0507028. The text was submitted by the author in English.     

Semiclassical quantization of SU(3) skyrmions

Semiclassical quantization of the SU(3)-skyrmion zero modes is performed by means of the collective coordinate method. The quantization condition known for SU(2) solitons quantized with SU(3) collective coordinates is generalized for SU(3) skyrmions with strangeness content different from zero. The quantization of the dipole-type configuration with large strangeness content found recently is considered as an example and the spectrum and the mass splittings of the quantized states are estimated. The energy and baryon number density of SU(3) skyrmions are presented in a form emphasizing their symmetry in different SU(2) subgroups of SU(3), and a lower bound for the static energy of SU(3) skyrmions is derived. Zh. éksp. Teor. Fiz. 112, 1941–1958 (December 1997) Published in English in the original Russian journal. Reproduced here with stylistic changes by the Translation Editor.     

Relativistic invariant approach to the parity violation in np→dγ capture

It is shown that the consistent relativistic invariant approach to the parity violation in np→dγ capture of thermal neutrons leads to results which differ essentially from those of the nonrelativistic approach. In particular the isospin selection rule established earlier for the photon circular polarization is charged due to the contribution of “relativistic” parity violating components of the deuteron and np-scattering wave function.     

Novel 5-dimethylamino-1- and 2-indanyl uracil derivatives

5-Dimethylamino-1-aminoindan undergoes thermal decomposition and reacts with 6-chlorouracil to give 5-indanyl-6-chlorouracil derivative 9. The formation of 9 may be rationalized by a putative mechanism based on the intermediacy of the imminium methide species 8a.     

On phonon-wind-driven spin injection and the conductivity mismatch problem

Spin injection from a ferromagnetic metal into a semiconductor driven by a constant phonon flow is considered. It is shown that diffusive (as opposed to electrical) spin injection gives rise to a highly spin-polarized current through the semiconductor. In other words, phonon-wind-driven injection under certain conditions eliminates the conductivity mismatch responsible for reduced spin polarization of the electric current injected from a ferromagnetic metal into a semiconductor.