New precise measurement of the pion weak form factors in pi+-->e+ nugamma decay.

We have measured the pi+-->e+ nugamma branching ratio over a wide region of phase space, based on a total of 65 460 events acquired using the PIBETA detector. Minimum-chi2 fits to the measured (E(e+), E(gamma) energy distributions result in the weak form factor value of F(A)=0.0119(1) with a fixed value of F(V)=0.0259. An unconstrained fit yields F(V)=0.0258(17) and F(A)=0.0117(17). In addition, we have measured a=0.10(6) for the dependence of F(V) on q2, the e+ nu pair invariant mass squared, parametrized as F(V)(q2)=F(V)(0)(1+aq(2)). The branching ratio for the kinematic region E(gamma)>10 MeV and theta(e(+)gamma)>40 degrees is measured to be B(expt)=73.86(54)x10(-8). Earlier deviations we reported in the high-E(gamma)-low-E(e+) kinematic region are resolved without a tensor term. We also derive new values for the pion polarizability alpha(E)=2.78(10)x10(-4) fm3 and neutral pion lifetime tau(pi0)=(8.5+/-1.1)x10(-17) s.

Precise measurement of the pi+-->pi0 e+nu branching ratio.

Using a large acceptance calorimeter and a stopped pion beam we have made a precise measurement of the rare pi(+)-->pi(0)e(+)nu (pi(beta)) decay branching ratio. We have evaluated the branching ratio by normalizing the number of observed pi(beta) decays to the number of observed pi(+)-->e(+)nu (pi(e2)) decays. We find the value of Gamma(pi(+)-->pi(0)e(+)nu)/Gamma(total)=[1.036+/-0.004(stat)+/-0.004(syst)+/-0.003(pi(e2))]x10(-8), where the first uncertainty is statistical, the second systematic, and the third is the pi(e2) branching ratio uncertainty. Our result agrees well with the standard model prediction.

Precise measurement of the pion axial form factor in the pi+-->e+nugamma decay.

We have studied radiative pion decays pi(+)-->e(+)nugamma in three broad kinematic regions using the PIBETA detector and a stopped pion beam. Based on Dalitz distributions of 41 601 events we have evaluated absolute pi-->enugamma branching ratios in the three regions. Minimum chi(2) fits to the integral and differential (E(e(+)),E(gamma)) distributions result in the axial-to-vector weak form factor ratio of gamma identical with F(A)/F(V)=0.443(15), or F(A)=0.0115(4) with F(V)=0.0259. However, deviations from standard model predictions in the high-E(gamma)-low-E(e(+)) kinematic region indicate the need for further theoretical and experimental work.

Bioamines and proteins in the saliva and salivary glands of Palaearctic blackflies (Diptera: Simuliidae).

To elucidate the mechanisms of skin-reactions to blackfly bites, components in the saliva and salivary glands of Simulium lineatum and S. equinum females were studied. Histamine, putrescine, spermine, N1-monoacetyl-spermine, and spermidine were detected in both the saliva and salivary gland extract through high-performance liquid chromatography (HPLC), the content of histamine being much higher than that of the other amines. Whereas histamine concentration was increased by food stimulation and actual feeding, the content of the other amines did not differ from that of non-stimulated flies. S. lineatum and S. equinum females differed significantly in their spermine and spermidine contents, autumn and spring generation females did not differ from each other. The dispersion of histamine in the salivary glands of male and female S. lineatum and S. equinum was demonstrated through histochemical staining. The globular proteins of the salivary glands were fractionated by chromatography and electrophoresis, the molecular weight of proteins and the enzymatic activity of esterase were also determined.

Quantitating histamine in the saliva and salivary glands of two Palaearctic blackfly species (Diptera: Simuliidae).

Saliva was collected from females of Boophthora erythrocephala (Simulium erythrocephalum) and Wilhelmia lineata (S. lineatum) as they were feeding on a saline-ATP solution through an artificial silicone membrane. The histamine content of the saliva was measured by high-performance liquid chromatography (HPLC). The amount of histamine salivated by B. erythrocephala (2.9 ng/individual when feeding to repletion) was more than four times that released by W. lineata (0.7 ng/individual). For both species, the quantity of histamine salivated increased with duration of feeding and partially with the age of females. The proportion of histamine retaines by in vitro fed W. lineata averaged 36.1% W. lineata females engorged on saline-ATP solution, or stimulated for feeding with the same medium, produced significantly more hist-amine than died unstimulated flies.

Artificial feeding of west African Simulium damnosum Theobald s.l. (Diptera: Simuliidae) on man, domestic mammals and birds.

A population of known species composition (mainly Simulium damnosum s.s. with some S. sirbanum), was fed on chicken, guinea-fowl, rabbit, goat, sheep, and man, using simple techniques under similar conditions. Significant differences in feeding rates were found between the different host species, on different parts of the body, at times also between different individuals of the same species, and between techniques employed. On less favoured hosts wild-caught flies usually gave better results than laboratory emerged females. Taking both wild-caught and laboratory emerged flies into consideration, rabbit, man and guinea-fowl gave the best results, with the latter being particularly suitable.

Artificial feeding of West African Simulium damnosum Theobald s.l. (Diptera: Simuliidae) through membranes and their subsequent fecundity.

Simulium damnosum s.l. females were offered blood through artificial membranes using a feeding apparatus in which the blood is kept warm and stirred. Feeding rates and egg production were compared using a synthetic silicone or a latex membrane and ten different kinds of blood with and without added adenosine-tri-phosphate (ATP). Feeding rates were usually higher with silicone than with latex membranes. Wild flies captured just before starting to feed on man, usually fed better than females that had emerged from pupae in the laboratory. Wild-caught flies showed best results when deep-frozen human blood with EDTA or fresh human blood from a blood bank was offered through a silicone membrane. Using a latex membrane they fed best on "instant" and fresh human blood from a blood bank. Laboratory-emerged females which were offered blood only through the silicone membrane, fed best on freeze-dried porcine blood or on human blood with EDTA, both with ATP. Optimal feeding rates were obtained with one day old flies and membrane temperatures between 37.0 and 39.5 degrees C. Real fecundity depended on blood-meal volume. Females that took a complete meal on man produced 377 eggs per fly. Since a higher percentage of flies fed through membranes took small or medium sized blood meals, their fecundity was correspondingly lower (295 eggs per fly).