We reconsider the strength of the electroweak phase transition in the singlet Majoron extension of the Standard Model, with a low ( < ∼ TeV) scale of the singlet VEV. A strongly first order phase transition, of interest for electroweak baryogenesis, is found in sizeable regions of the parameter space, especially when the cross-coupling λ hs |S| 2 |H| 2 between the singlet and the doublet Higgs is significant. Large Majorana Yukawa couplings of the singlet neutrinos, y i Sν c i ν i , are also important for strengthening the transition. We incorporate the LEP and Tevatron constraints on the Higgs masses, and electroweak precision constraints, in our search for allowed parameters; successful examples include singlet masses ranging from 5 GeV to several TeV. Models with a strong phase transition typically predict a nonstandard Higgs with mass in the range 113 GeV < ∼ m H < ∼ 200 GeV and production cross sections reduced by mixing with the singlet, with cos 2 θ significantly less than 1. We also find examples where the singlet is light and the decay H → SS can modify the Higgs branching ratios relative to Standard Model expectations. * current address: Barclays Capital Japan Limited

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An inversional-rotational isomeric state (IRIS) scheme including first-order to fourth-order intramolecular interactions has been developed and applied to conformational analysis of poly(trimethylene imine) (PTMI) and poly(N-methyltrimethylene imine) (PMTMI). Bond conformations and conformational energies of PTMI and PMTMI were evaluated from ab initio molecular orbital calculations at the MP2/6-311++G(3df, 3pd)//HF/6-31G(d) level and 1H and 13C NMR experiments for the monomeric model compounds, CH3NR1CH2CH2CH2NR2CH3 (R1 = R2 = H; R1 = H and R2 = CH3; R1 = R2 = CH3). The IRIS analysis yielded the following data on the polymers at 25 °C:  the characteristic ratio for the infinite chain, 3.5 (PTMI) and 4.2 (PMTMI); trans fractions of the C−C and C−N bonds, respectively, 0.29 and 0.77 (PTMI) and 0.40 and 0.65 (PMTMI); the meso-diad probability, 0.44 (PTMI) and 0.48 (PMTMI). Intramolecular hydrogen bonds were found in the polyimines:  PTMI, N−H···N (the interaction energy, −0.83 kcal mol-1) and C−H···N (−0.15 kcal mol-1); PMTMI, C−H···N (−0.40 kcal mol-1). The chain dimension, stereochemical configuration, and bond conformations of the polyimines are sensitive to the first-order interaction energy around the C−C bond and the hydrogen-bond energies. Polar solvents weaken the hydrogen bonds to increase the chain dimension and randomize the configuration.

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Utilizing horseradish peroxidase as a tracer, electron microscopic studies were done on the blood-optic nerve and fluid-optic nerve barrier to the peroxidase diffusion. Following intravenous injection the peroxidase was observed to fill the lumen of the capillaries of the laminar, prelaminar and orbital portions of the optic nerve but there was no penetratation of the capillary walls. The obstruction of the tracer diffusion out of capillary walls was attributed to the tight junctions between the endothelial cells. Peroxidase penetration was also absent in the capillaries of the pia and dura mater, however, was observed in pinocytotic vesicles of the endothelial cells. Lateral diffusion from the surrounding choroid into the optic nerve was detected but diffusion from the prelaminar optic nerve into the juxta-optic nerve retina was prevented by the Kuhnt intermediary tissue. Tight junctions which prevented peroxidase diffusion were found between the glial cells of the Kuhnt tissue, and this tissue was the barrier between the prelaminar optic nerve and the juxta-optic nerve retina. Peroxidase which was given into the lateral ventricle of the brain appeared in the subarachnoidal space around the optic nerve and penetrated freely into the optic nerve. The pial surface of the optic nerve possess no barrier activity. Peroxidase could be traced along the intercellular space between glial cells and optic nerve fibers. The basal lamina of the optic nerve capillaries was filled with peroxidase but diffusion into the capillary lumen was obstructured by the tight junctions between the endothelial cells.

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