Pesticide residues in boreal arable soils: Countrywide study of occurrence and risks.

Large volumes of pesticides are applied every year to support agricultural production. The intensive use of pesticides affects soil quality and health, but soil surveys on pesticide residues are scarce, especially for northern Europe. We investigated the occurrence of 198 pesticide residues, including both banned and currently used substances in 148 field sites in Finland. Results highlight that pesticide residues are common in the agricultural soils of Finland. A least one residue was found in 82% of the soils, and of those 32% contained five or more residues. Maximum total residue concentration among the conventionally farmed soils was 3043 µg/kg, of which AMPA and glyphosate contributed the most. Pesticide residues were also found from organically farmed soils, although at 75-90% lower concentrations than in the conventionally farmed fields. Thus, despite the application rates of pesticides in Finland being generally much lower than in most parts of central and southern Europe, the total residue concentrations in the soils occurred at similar or at higher levels. We also established that AMPA and glyphosate residues in soil are significantly higher in fields with cereal dominated rotations than in grass dominated or cereal-grass rotations. However, risk analyses for individual substances indicated low ecological risk for most of the fields. Furthermore, the total ecological risk associated with the mixtures of residues was mostly low except for 21% of cereal dominated fields with medium risk. The results showed that the presence of mixtures of pesticide residues in soils is a rule rather than an exception also in boreal soils. In highly chemicalized modern agriculture, the follow-up of the residues of currently used pesticides in national and international soil monitoring programs is imperative to maintain soil quality and support sustainable environment policies.

The psychosocial effects of acne on adolescents.

To describe the psychosocial impact of acne on adolescents, and, in particular, to assess whether self-concept is affected by medical treatment, we evaluated 39 teenagers presenting for care to a community-based dermatologist. Prior to and following treatment, subjects completed a self-assessment questionnaire, the Piers-Harris self-concept scale, and underwent an objective assessment of acne severity. Fifty-eight percent of subjects were dissatisfied with their facial appearance and this in turn was correlated with feelings of embarrassment and social inhibition (for each, r = 0.48, P less than or equal to 0.005). Subjects' rating of acne severity, but not the dermatologist's, was correlated with dissatisfaction with facial appearance (r = 0.45, P less than or equal to 0.005). Despite these findings, the mean Piers-Harris total t-score (55.4 +/- 7.4) was within the normal range. Fourteen subjects (36%) returned for follow-up and 71% of these were judged by both the dermatologist and themselves to have improved. Following therapy, significant reductions in the adverse consequences of acne were observed with 42% of subjects reporting that their facial appearance was more acceptable to peers, 50% being less embarrassed, and 58% feeling less socially inhibited. Minimal improvement in mean Piers-Harris total t-score was observed (54.6 to 57.4, P = 0.004, paired t-test). Our data demonstrate that acne is perceived by adolescents to have important negative personal and social consequences, and that improvement in these areas may accompany medical treatment.

Theoretical model of phase separation of erythrocytes, platelets, and plasma at branches.

Analytical expressions for the changes of the erythrocyte and platelet concentration are calculated as blood flows through a single bifurcation. The effect of the separation surface, which divides the blood into the two daughter vessels, upon the concentration changes is studied. Numerical fitting to the experimental data shows that both the erythrocyte and platelet distributions across the vessel are nonuniform. The maximum of the erythrocyte concentration is in the core, and of the platelet concentration, in the vicinity of the wall. A separation surface that is convex towards the axis of the vessel yields better fit to the experimental data than a concave one. Together with other studies, this suggests that flow-divider geometry depends on flow conditions and the vessel diameters. The results can be used for estimation of the distribution of erythrocytes and platelets in the microvasculature.

Theoretical analysis of regional blood flow studies.

Regional blood flow measurements were analyzed using a two-compartment model. The distribution of injected tracer between blood and tissue was assumed to be in equilibrium only at the beginning of the experiment. Equations for the determination of the partition coefficient of injected radionuclides from in vivo measurements were derived. These equations can also be used for estimation of the relative blood content of a tumor or an organ. The results were applied to experiments, where three diffusible radionuclides were injected simultaneously into patients with diagnosed tumors.

The relationship between growth and allometry.

The asymptotic allometric equations are derived by considering the relative growth of different physiological and anatomical quantities. The growth rate is assumed to be proportional to the value of the quantity, where the proportion coefficient depends on time. The allometric exponents are calculated for some organs of man and compared with the experimental values for primates. The exponents are generally time-dependent during the growth. The effect of the choice of the origin of time axis on the asymptotic allometric exponents is studied.