Discrete symmetries, invisible axion and lepton number symmetry in an economic 3-3-1 model

We show that Peccei-Quinn and lepton number symmetries can be a natural outcome in a 3-3-1 model with right-handed neutrinos after imposing a Z_11 x Z_2 symmetry. This symmetry is suitably accommodated in this model when we augmented its spectrum by including merely one singlet scalar field. We work out the breaking of the Peccei-Quinn symmetry, yielding the axion, and study the phenomenological consequences. The main result of this work is that the solution to the strong CP problem can be implemented in a natural way, implying an invisible axion phenomenologically unconstrained, free of domain wall formation and constituting a good candidate for the cold dark matter.Comment: 17 pages, Revtex

Can R-parity violation explain the LSND data as well?

The recent Super-Kamiokande data now admit only one type of mass hierarchy in a framework with three active and one sterile neutrinos. We show that neutrino masses and mixings generated by R-parity-violating couplings, with values within their experimental upper limits, are capable of reproducing this hierarchy, explaining all neutrino data particularly after including the LSND results.Comment: 7 pages, Latex, 3 PS figures; in v2 a few clarifying remarks included and two references added (to appear in Physical Review D

The Earth: Plasma Sources, Losses, and Transport Processes

This paper reviews the state of knowledge concerning the source of magnetospheric plasma at Earth. Source of plasma, its acceleration and transport throughout the system, its consequences on system dynamics, and its loss are all discussed. Both observational and modeling advances since the last time this subject was covered in detail (Hultqvist et al., Magnetospheric Plasma Sources and Losses, 1999) are addressed

Pasteurella multocida type A as the primary agent of pneumonia and septicaemia in pigs

Abstract: In order to understand better the pathological aspects and spread of Pasteurella multocida type A as the primary cause of pneumonia in pigs, was made an experiment with intranasal inoculation of different concentrations of inocula [Group (G1): 108 Colony Forming Units (CFU)/ml; G2: 107 CFU/ml; G3: 106 CFU/ml and G4: 105 CFU/ml], using two pigs per group. The pigs were obtained from a high health status herd. Pigs were monitored clinically for 4 days and subsequently necropsied. All pigs had clinical signs and lesions associated with respiratory disease. Dyspnoea and hyperthermia were the main clinical signs observed. Suppurative cranioventral bronchopneumonia, in some cases associated with necrosuppurative pleuropneumonia, fibrinous pericarditis and pleuritic, were the most frequent types of lesion found. The disease evolved with septicaemia, characterized by septic infarctions in the liver and spleen, with the detection of P. multocida type A. In this study, P. multocida type A strain #11246 was the primary agent of fibrinous pleuritis and suppurative cranioventral bronchopneumonia, pericarditis and septicaemia in the pigs. All concentrations of inoculum used (105-108 CFU/ml) were able to produce clinical and pathological changes of pneumonia, pleuritis, pericarditis and septicemia in challenged animals

Measurement of equilibrium constants for complex formation between phenol and hydrogen-bond acceptors by kinetic laser flash photolysis

Peer reviewed: YesNRC publication: Ye

Mechanism of hydroxylation of alkanes by dimethyldioxirane. A radical-clock study

The oxidation of 2-cyclopropylpropane by dimethyldioxirane (DMD) to 2-cyclopropyl-propan-2-ol is not a free-radical chain reaction. It is suggested the free-radical chain observed by Minisci et al.8 when alkane / DMD reactions were carried out in the presence of CCl3Br involves H-atom abstraction from the alkane by Cl3,COO\ub7 (in air) and by Me2C(O\ub7)OCCl3, as well as by the Cl3C\ub7 radical. \ua9 1995.Peer reviewed: YesNRC publication: Ye

Kinetic solvent effects on hydroxylic hydrogen atom abstractions are independent of the nature of the abstracting radical. Two extreme tests using vitamin E and phenol

Rate constants have been measured at 25\ub0C in 13 solvents (S) for abstraction of the phenolic hydrogen atom from \u3b1-tocopherol (TOH) by tert-butoxyl (BO .) k(TOH/BO)(S), and by 2,2-diphenyl-1-picrylhydrazyl (DPPH .), k(TOH/DPPH)(S), and in eight solvents for abstraction of the phenolic hydrogen atom from phenol by cumyloxyl, k(PhOH/CumO)(S), and DPPH .k(PhOH/DPPH)(S). Over the range of solvents examined k(TOH/BO)(S) and k(TOH/DPPH)(S) vary by a factor of ca. 65 and k(PhOH/CumO)(S) and k(PhOH/DPPH)(S) vary by a factor of ca. 120. In accordance with a prediction, the kinetic solvent effect is essentially identical for the same substrate and is independent of the attacking radical. That is, for almost any pair of solvents, A and B (k(TOH/BO)(A)/k(TOH/BO)(B))/(k(TOH/DPPH)(A)/k(TOH/DPPH)(B)) ~ 1.0. The same applies with phenol as the substrate. Exceptions to this 1:1 relationship occur when one of the reactions becomes partly diffusion controlled and in the solvent tert-butyl alcohol in which DPPH . shows a larger reactivity than would be expected. The absolute magnitudes of the alkoxyl and DPPH rate constants in the same solvent differ by a factor of over 1000000 (10 6) for \u3b1-tocopherol and by 10000000000 (10 10) for phenol! We have therefore confirmed, under extreme conditions, a new, unifying principle for free radical chemistry in solution.Peer reviewed: YesNRC publication: Ye

Bicyclo[1.1.1]pent-1-yl: A tertiary alkyl radical with enhanced reactivity

Absolute rate constants for reactions of bicyclo[1.1.1]pent-1-yl radicals with \u3b1-methylstyrene (1.4 x 107 M-1s-1) and 1,4-cyclohexadiene (4.6 x 105 M-1s-1) at 25\ub0C were measured by laser flash photolysis. This bridgehead radical is more reactive than tert-butyl which we attribute to its high s-character and the absence of steric shielding of the radical center.Peer reviewed: YesNRC publication: Ye

Solvent effects on the antioxidant activity of vitamin E

Peer reviewed: YesNRC publication: Ye