Parameter dependence and outcome dependence in dynamical models for state vector reduction

We apply the distinction between parameter independence and outcome independence to the linear and nonlinear models of a recent nonrelativistic theory of continuous state vector reduction. We show that in the nonlinear model there is a set of realizations of the stochastic process that drives the state vector reduction for which parameter independence is violated for parallel spin components in the EPR-Bohm setup. Such a set has an appreciable probability of occurrence ( 1/2). On the other hand, the linear model exhibits only extremely small parameter dependence effects. We investigate some specific features of the models and we recall that, as has been pointed out recently, if one wants to be able to speak of definite outcomes (or equivalently of possessed objective elements of reality) at finite times, one has to slightly change the criteria for their attribution to physical systems. The concluding section is devoted to a detailed discussion of the difficulties which one meets when one tries to take, as a starting point for the formulation of a relativistic theory, a nonrelativistic scheme which exhibits parameter dependence. Here we derive a theorem which identifies the precise sense in which the occurrence of parameter dependence forbids a genuinely relativistic generalization. Finally we show how the appreciable parameter dependence of the nonlinear model gives rise to problems with relativity, while the extremely weak parameter dependence of the linear model does not give rise to any difficulty, provided one takes into account the appropriate criteria for the attribution of definite outcomes.Work supported in part by the Trieste Section of the INFN.     

Laser-induced reactions of NO2 in the visible region

The reaction of NO₂ with isobutane, induced by 488 nm laser radiation, to form 2-nitro-2-methylpropane has been investigated and the results computer-modeled according to two possible reaction mechanisms. The first scheme involves the direct abstraction of H from isobutane by vibronically excited NO₂ (NO ₂ ^* ), and the second, abstraction by an intermediate NO₃ radial produced by NO ₂ ^* +NO₂. The modeling results strongly support the NO ₂ ^* scheme as the dominant reaction mechanism.     

Alkynenitriles: chelation-controlled conjugate additions

[reaction: see text] Chelation between gamma-hydroxybutynenitrile and Grignard reagents triggers a particularly facile anionic conjugate addition reaction. Structurally diverse Grignard reagents add with equal efficiency, providing an intermediate anion that stereoselectively alkylates benzaldehyde in an overall addition-alkylation reaction.     

Muonium formation and the “missing fraction” in vapors

The vapor phase fractional polarizations of positive muons thermalizing as the muonium atom (P _M) and in diamagnetic environments (P _D) has been measured in H₂O, CH₃OH, C₆H₁₄, C₆H₁₂, CCl₄, CHCl₃, CH₂Cl₂ and TMS, in order to compare with the corresponding fractions measured in the condensed phases. There is a marked contrast in every case, with the vapor phase results being largely understandable in terms of a charge exchange/hot atom model. Unlike the situation in the corresponding liquids, there is no permanent lost fraction in the vapor phase in the limit of even moderately high pressures (1 atm); at lower pressures, depolarization is due to hyperfine mixing and is believed to be well understood. For vapor phase CH₃OH, C₆H₁₄, C₆H₁₂, and TMS therelative fractions are found to be pressure dependent, suggesting the importance of termolecular hot atom (or ion) reactions in the slowing down process. For vapor phase H₂O and the chloromethanes, the relative fractions are pressure independent. For CCl₄,P _M=P _D0.5 in the vapor phase vs.P _D=1.0 in the liquid phase; fast thermal reactions of Mu likely contribute significantly to this difference in the liquid phase. For H₂O,P _M 0.9 andP _D0.1 in the vapor phase vs.P _D 0.6 andP _M0.2 in the liquid phase. Water appears to be the one unequivocal case where the basic charge exchange/hot atom model is inappropriate in the condensed phase, suggesting, therefore, that radiation induced spur effects play a major role.     

Regio- and stereoselective oxetane formation via paterno-buchi photocycloaddition

Carbonyl 2 + 2 photoaddition occurs selectively to the alkene moiety of 3-(4-methyl-3-pentenoxy)pyridine. Photolysis of alkene containing pyridines in acetophenone gives rise to an oxetane which is obtained with extremely high diastereoselectivity as shown by analysis of the major 2 + 2 photoproduct. A second photoproduct, 2,3-dihydroxy-2,3-diphenylbutane, is obtained as a result of acetophenone coupling.     

Simultaneous analysis of methionine- and leucine-enkephalin from rat brain: quantification by liquid chromatography-electrochemistry

This study focuses on the application of liquid chromatography with electrochemical detection (LC-ED) for the analysis of methionine-enkephalin (ME) and leucine-enkephalin (LE) extracted from rat brain regions. The high applied potentials necessary for enkephalin detection required the development of an efficient sample processing protocol. Brain extracts were processed using chromatographic mode sequencing (CMS). The decrease in electroactive interfering substances by CMS improved the chromatographic resolution of ME and LE and the electrode performance. Other qualitative and analytical methods were used to evaluate the enkephalin data obtained by LC-ED for rat brain regions. This study demonstrates that LC-ED provides both the sensitivity and specificity necessary for the analysis of enkephalins from rat brain regions.     

Muonium chemistry: kinetics of the gas phase reaction Mu + F2 → MuF + F from 300 to 400 K

The MSR (muonium spin rotation) technique was used to measure the chemical reaction rate for Mu + F₂ → MuF + F in N₂ moderator at ≈ 1 atm from 295 to 383 K giving the Arrhenius expression: log₁₀k (?/mole s) = (10.83 ± 0.20) - (200 ± 50)/T, with k = (1.46 ± 0.11) × 10¹⁰ ?/mole s at 300 K. This is at least 6.8 times the room temperature rate constant for the analogous H atom reaction. The measured activation energy and enhancement over the H reaction rate are indicative of significant tunnelling in the Mu reaction, in agreement with the recent collinear quantum mechanical calculations of Connor et al.     

Thermally stimulated luminescence and conductivity — Additional tools for thermal analysis of polymers

The physical phenomena underlying thermally stimulated luminescence and conductivity measurements, logically considered as complementary to conventional thermal analysis measurements, are outlined. The equipment and samples required to make such measurements are briefly described, and the basic concepts underpinning the interpretation of the data sketched. Some recent experimental data, chosen to reflect the sensitivity of thermally stimulated luminescence and conductivity to doping of the sample and changes in its morphology, are presented and discussed.

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Zusammenfassung Es werden diejenigen physikalischen Erscheinungen umrissen, auf denen Messungen von thermisch stimulierter Lumineszenz und Leitfähigkeit basieren, die logisch als ergänzend zu herrkömmlichen thermoanalytischen Messungen betrachtet werden. Zur Durchführung von Messungen dieser Art benötigte Einrichtungen und Proben werden kurz beschrieben und Grundbegriffe für die Interpretierung der experimentellen Ergebnisse skizziert. Einige frühere experimentelle Daten, die ausgewählt wurden, um die Empfindlichkeit der thermisch stimultierten Lumineszenz und Leitfähigkeit gegenüber Dopen der Probe bzw. Vernäderungen in ihrer Morphologie zu verdeutlichen, werden vorgestellt und diskutiert.

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This review was written during my stay at the Institute for Molecular Science as Visiting Professor. I wish to thank Professors Y. Maruyama and H. Inokuchi for their thoughtful hospitality, and the Japanese Ministry of Education Science and Culture for financial assistance.     

Pre-irradiation treatments for CR-39 detectors

The production of track-spots in CR-39 detectors for alpha particles and the subsequent optical counting of the detectors are often influenced by foreign substances deposited on the surface of the detectors. The removal of these substances can be achieved using chemicals for pre-irradiation treatment. Two methods of pre-irradiation treatment were studied in the present experiments. One of them involves the dipping of the detectors in ethanol. In the other method, the detectors were treated in 6N KOH etchant prior to exposure. It was found that prolonged treatment could only produce a reduction in the track density of less than 20%.