Dispersion polymerization of styrene: Effect of surfactant

The influence of poly(vinyl alcohol) (PVA), a steric stabilizer, and sodium dodecyl sulfate (SDS), an electrostatic stabilizer, on the stability of styrene dispersion polymerized systems was studied. It was shown that in stabilization by PVA there was pronounced bridging of the submicron emulsion particles to 10-μ dispersion particles and that the emulsion particles could not be washed off. In SDS stabilization, on the other hand, the emulsion formed was easily washed off because bridging with SDS does not occur. The surface tension of the aqueous phase measured during polymerization showed different characteristics for stable and unstable systems.     

Hypernuclei as chiral solitons

Identification of flavored multiskyrmions with the ground states of known hypernuclei is successful for several of them, e.g., for the isodoublet _Λ ⁴ H- _Λ ⁴ He and isoscalars _Λ ⁵ He and _Λ ⁷ Li. In other cases, agreement is not so good, but as the baryon number increases, the behavior of the binding energy qualitatively agrees with the data. Charmed or beautiful hypernuclei are predicted within this approach to be bound more strongly than strange hypernuclei. This conclusion is stable with respect to a certain variation of poorly known heavy flavor decay constants.     

Flavored multiskyrmions

Static properties of multiskyrmions with baryon numbers up to 8 are calculated on the basis of the recently given rational map Ansätze. The spectra of baryonic systems with strangeness, charm, and bottom are considered within a “rigid oscillator” version of the bound state soliton model. It is suggested that the recently observed negatively charged nuclear fragment can be considered as a quantized strange multiskyrmion with B=6 or 7. In agreement with previous observations, baryonic systems with charm or bottom have a better chance of being bound by the strong interactions than do strange baryonic systems.     

Baryon asymmetry of the proton sea at low-x

We predict a nonvanishing baryon asymmetry of the proton sea at low x. It is expected to be about 7% and nearly x-independent at x < 0.5 × 10^-3. The asymmetry arises from the baryon-antibaryon component of the Pomeron, rather than from the valence quarks of the proton, which are wide believed carriers of baryon number. Experimental study of x-distribution of the baryon asymmetry of the proton sea can be performed in ep or γp interactions at HERA, where x ～ 10^-5 are reachable, smaller than at any of existing or planned proton colliders.     

Proton NMR studies of reduced porphyrin compounds

Detailed ¹H NMR studies of ms tetraphenylchlorins (H₂TPC), new amino- and hydroxypyrroline substituted ms tetraphenylchlorins and ms tetraphenylisobacteriochlorins (H₂TPisoB) are presented and discussed. The results obtained are consistent with the general aspects of the ring current models as applied to the parent porphyrins. According to proton chemical shifts a gradual reduction in the magnitude of the ring current is observed in the order ms tetraphenylporphyrin (H₂TPP) > H₂TPC> ms tetraphenylbacteriochlorin (H₂TPB) > H₂TPisoB. The ¹H NMR spectra show chemical non-equivalence of the pyrroline ring protons due to adjacent substituents, and effects of steric constraints on the aminoalkyl substituents due to the close vicinity to the meso phenyl rings. The non-equivalence of the methylene protons of the pyrroline ring produces geminal coupling between the two methylene protons and vicinal coupling with the adjacent pyrroline proton, more pronounced in H₂TPC? OH and in . Restricted configuration of the methylene groups in the ethyl groups of H₂TPC? C(H)(CH₃)N(CH₂CH₃)₂ produces observable geminal coupling between the methylene protons. ¹H NMR reveals the difference between two types of meso phenyls in the chlorins, and three types of meso phenyls in isobacteriochlorins, as reflected in the chemical shifts of the o-phenyl protons.     

The quark model and exchange degeneracy

The quark model and exchange degeneracy of leading Reggeon contributions to quark-quark scattering amplitudes are combined for deriving a number of relations on polarizations, the real parts of forward scattering amplitudes and total cross sections. The comparison of these relations with experimental data is discussed.The authors are grateful to Ya. I.Asimov, E. M.Levin and L. L.Frankfurt for their interest in this work.     

New theta constant identities

The residue theorem is employed to obtain new identities amongpthe powers of theta constants with rational characteristics. The technique is then used to derive some known identities of Ramanujan. Dedicated to John Thompson for his many original contributions to mathematics Research by HMF partially sponsored by the Edmund Landau Center for Research in Mathematical Analysis, supported by the Minerva Foundation (Germany).     

On a Roelcke-precompact Polish group that cannot act transitively on a complete metric space

We study when a continuous isometric action of a Polish group on a complete metric space is, or can be, transitive. Our main results consist of showing that for certain Polish groups, namely Aut* (μ) and Homeo+ [0, 1], such an action can never be transitive (unless the space acted upon is a singleton).We also point out that in all known examples, this pathology coincides with the pathology of Polish groups that are not closed permutation groups and yet have discrete uniform distance, asking whether there is a relation. We conclude with a general characterisation/classification of transitive continuous isometric actions of a Roelcke-precompact Polish group on a complete metric space. In particular, the morphism from a Roelcke-precompact Polish group to its Bohr compactification is surjective.     

Cusp forms for congruence subgroups of and theta functions

In this paper we use theta functions with rational characteristic to construct cusp forms for congruence subgroups of .The action of the quotient group on these forms is conjugate to the linear action of on . We show that these forms are higher-dimensional analogues of the Fricke functions.