This total PM10 background was further subdivided into background primary and background natural and secondary fractions using NOx measurements also collected at these background/suburban sites.
Free-floating sections were initially incubated in blocking solution (0.1 mol/L phosphate-buffered saline [PBS], 5% serum, 1% Triton X-100, 0.5% Tween 20, 2% skim milk) for 1 h at room temperature to reduce nonspecific background, and then with primary and secondary antibodies overnight at 4°C.
This leads us to consider the distinction between primary and secondary background effects.
We added a background concentration to all computed primary and secondary PM10 concentrations originating from Swiss sources in the emission inventory data, which captured most emissions except for road transport in ventilated tunnels, air transport at 200 m above ground or higher, water transport, and biogenic particles.
The background values (obtained in the absence of primary and secondary antibody, or with no primary antibody) were very low (Fig. 4b).
The effect of these noninventoried emissions, albeit negligible [< 1.0 μg/m (SAEFL 2003)], was implicitly included in the background concentration, which primarily accounted for imported primary and secondary particles.
With regard to educational aspirations, Boudon (1974) differentiate between primary and secondary effects of social background (for more information see, e.g., Maaz et al. 2006).
He said the council "deserved credit" for improvements in the performance of primary and secondary children from "both disadvantaged backgrounds and the most able students".
Besides the primary and secondary outcome measures we assess some background variables which are considered to be predictors, confounders or effect modifiers.
Background: Therapy of nocturnal hypertension was shown to be beneficial for primary and secondary prevention of stroke.
