Distribution of the timber quality attribute ‘knot surface’ in logs of Fagus sylvatica L. from pure and mixed forest stands

European Journal of Forest Research - Research on mixed forests has mostly focused on tree growth and productivity, or resistance and resilience in changing climate conditions, but only rarely on...     

Fast routing in road networks with transit nodes

When you drive to somewhere far away, you will leave your current location via one of only a few important traffic junctions. Starting from this informal observation, we developed an algorithmic approach, transit node routing, that allows us to reduce quickest path queries in road networks to a small number of table lookups. For road maps of Western Europe and the United States, our best query times improved over the best previously published figures by two orders of magnitude. This is also more than one million times faster than the best known algorithm for general networks.     

Chloroquine resistance in Plasmodium falciparum malaria parasites conferred by pfcrt mutations

Plasmodium falciparum chloroquine resistance is a major cause of worldwide increases in malaria mortality and morbidity. Recent laboratory and clinical studies have associated chloroquine resistance with point mutations in the gene pfcrt. However, direct proof of a causal relationship has remained elusive and most models have posited a multigenic basis of resistance. Here, we provide conclusive evidence that mutant haplotypes of the pfcrt gene product of Asian, African, or South American origin confer chloroquine resistance with characteristic verapamil reversibility and reduced chloroquine accumulation. pfcrt mutations increased susceptibility to artemisinin and quinine and minimally affected amodiaquine activity; hence, these antimalarials warrant further investigation as agents to control chloroquine-resistant falciparum malaria.     

Limited efficacy of West Nile virus vaccines in large falcons (Falco spp.)

West Nile virus (WNV) can lead to fatal diseases in raptor species. Unfortunately, there is no vaccine which has been designed specifically for use in breeding stocks of falcons. Therefore the immunogenicity and protective capacity of two commercially available WNV vaccines, both approved for use in horses, were evaluated in large falcons. One vaccine contained adjuvanted inactivated WNV lineage 1 immunogens, while the second represented a canarypox recombinant live virus vector vaccine. The efficacy of different vaccination regimes for these two vaccines was assessed serologically and by challenging the falcons with a WNV strain of homologous lineage 1. Our studies show that the recombinant vaccine conveys a slightly better protection than the inactivated vaccine, but moderate (recombinant vaccine) or weak (inactivated vaccine) side effects were observed at the injection sites. Using the recommended 2-dose regimen, both vaccines elicited only sub-optimal antibody responses and gave only partial protection following WNV challenge. Better results were obtained for both vaccines after a third dose, i.e. alleviation of clinical signs, absence of fatalities and reduction of virus shedding and viraemia. Therefore the consequences of WNV infections in falcons can be clearly alleviated by vaccination, especially if the amended triple administration scheme is used, although side effects at the vaccination site must be accepted.     

Estimation of local probabilities for exceeding threshold values in environmental monitoring

Contour or isopleth maps of regionalized variables are widely used in decision making without regard for the inherent uncertainty of interpolated contours. One concept for addressing the accuracy of contours given the data is the computation of the conditional probability of the value being lower than the contour. Two simple techniques for an approximate computation, indicator kriging and approximation by normal distribution quantiles, are applied to immission data. Since the assumption of a stationary underlying process does not seem justifiable, a moving windows technique is adopted.     

Combined cryopreservation of canine ejaculates collected at a one-hour interval increases semen doses for artificial insemination without negative effects on post-thaw sperm characteristics

A limiting factor in canine artificial insemination (AI) is the low number of insemination doses obtained per ejaculate. In this study, semen was collected from dogs (n = 28) either once and frozen directly after collection or the same dogs were submitted to a dual semen collection with a 1-hr interval and the two ejaculates were combined for cryopreservation. We hypothesized that combining two ejaculates increases semen doses per cryopreservation process without negative effects on semen characteristics. Total sperm count was lower in semen from a single semen collection in comparison with the combination of the first and second ejaculate of a dual semen collection (p < .001). The percentage of motile and membrane-intact spermatozoa determined by computer-assisted sperm analysis (CASA) in raw semen did not differ between single and combined dual ejaculates and was reduced (p < .001) by cryopreservation to the same extent in single (motility 73.7 ± 1.8%, membrane integrity 65.6 ± 2.2%) and combined dual ejaculates (motility 72.7 ± 2.3%, membrane integrity 64.6 ± 2.5%). The percentage of spermatozoa with morphological defects increased after cryopreservation (p < .001) but was similar in single and combined dual ejaculates. The CASA sperm velocity parameters decreased with cryopreservation (p < .001) but did not differ between single and combined dual ejaculates. The number of insemination doses increased from 2.7 ± 0.4 for single to 4.7 ± 0.8 for combined dual ejaculates (p < .01), based on 100 million motile spermatozoa per frozen-thawed semen dose. In conclusion, combining two ejaculates collected at short interval for one cryopreservation process increases the number of AI doses without compromising semen quality.     

Bodenkundliche Untersuchungen an Deckschichten in N-Togo

Pedological Examination of “Covering Layers” (Deckschichten) in Northern Togo “Covering layers” (Deckschichten) in northern Togo occur regularly and are widespread. Their composition varies according to the morphological situation. Only covering layers of the same morphological position are comparable. The uppermost covering layer is a product of subrecent geomorphodynamic activity. The origin of the material is still unknown. The contribution of termites to the genesis of covering layers in N-Togo is insignificant. The covering layer is the parent material of recent soil forming processes. The soils are generally stratified with polycyclic genesis. The composition, the thickness and the number of covering layers are causing the agronomic potential of these soils.     

Phosphorus-induced mobilization of colloids: model systems and soils

Increasing the phosphorus (P) saturation of sandy soils may cause an increase in the rate of transport of dissolved P to groundwater. We hypothesize that by increasing sorption of P, soil colloids such as iron (Fe) oxides are also mobilized, because the adsorption of P causes the surface charge to become more negative, which increases the repulsive forces between the colloids and the sand grains, and between the colloids in suspension. Goethite particles adsorbed to fine quartz sand and precipitated goethite coatings on coarse quartz sand were used as model systems to test this hypothesis. Soil samples from a Cambisol Bw horizon and a Gleysol Bg horizon were also investigated. We conducted a series of batch experiments with increasing concentrations of ortho‐P and inositol hexaphosphate (IHP). The adsorption of P and the dispersion of colloids were determined by measuring P, Fe, aluminium and carbon concentrations in supernatants before and after ultracentrifugation. Dispersed colloids were characterized according to their optical density, zeta potential and particle size. The addition of P caused mobilization of goethite and soil colloids when a critical P saturation, corresponding to a zeta potential of about ?20 mV, was exceeded. To induce colloid mobilization in soils, one to two orders of magnitude larger equilibrium concentrations of dissolved P were necessary, compared with those required for the model systems. The adsorption of IHP reduced the zeta potential of colloids more effectively than the adsorption of ortho‐P per mol P. Environmentally significant concentrations of colloidal P (> 0.1 mg P litre^?1) were released from soil samples at equilibrium concentrations of dissolved P < 0.1 mg P litre^?1. We conclude that the sorption and accumulation of P in sandy subsoils that might occur as a result of excessive fertilization might induce the mobilization of colloids and colloidal P.